All abstracts for ICOS Science Conference 2024

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10 Atmospheric GHG Monitoring Network of the metropolitan area of Barcelona

Poster

Gara Villalba1, Roger Curcoll2*

1Universitat Autònoma de Barcelona, Barcelona, Spain. 2UPC, Barcelona, Spain

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

The ICOS Cities Horizon 2020 project makes observations on Greenhouse Gases (GHG) emissions in densely populated urban areas, with the objective of developing useful tools and services to support the local climate action plans of cities. This project has expanded to 12 European cities, including Barcelona.The Barcelona conurbation area extents up to 4200 km2 and has a total population over 5 million habitants. It includes green areas, industrial zones and agricultural soils but also some areas with the highest density population in Europe. Four continuous atmospheric measurement stations of GHG have been implemented with Picarro gas analyzers of CO2 ,CH4 and water vapor, strategically placed in different characteristic areas of the urban conurbation: the ICM stations is located at the Barcelona seafront, IDAEA station in a university campus near a high traffic route inside Barcelona city, Observatori Fabra in a meteorological observatory in the middle of a mountain range 300m above Barcelona skyline (at 410 meters above sea level), and ICTA in a university building rooftop in the second metropolitan ring.

Here we present the results of the first two years of atmospheric monitoring data for these stations. The CO2 and CH4measurements are complemented with meteorological measurements to know the precedence of the air masses. The data obtained is used study the meteorological influence on concentrations and estimate the city's budget emissions with the help of models, in the frame of the URBAG project.

 

11 Carbon Dew Community of Practice: Anchoring Fair and Equitable Climate Solutions in Direct Atmospheric Flux Measurement

Poster

George Burba1,2,3*, Stefan Metzger4,5,6, CarbonDew CoP1

1CarbonDew, Lincoln, USA. 2Water for Food Global Institute, Lincoln, USA. 3LI-COR, Lincoln, USA. 4CabonDew, Boulder, USA. 5AtmoFacts, Boulder, USA. 6University of Wisconsin, Madison, USA

Session 15. Science communication and outreach to increase the impact of climate research

The Carbon Dew Community of Practice is an international non-profit representing carbon and climate experts from over 180 organizations. Our vision is to anchor fair and equitable climate solutions in direct atmospheric measurements, and our mission is to facilitate technology transfer by providing a medium for public and private entities to work together towards common goals. We strive to translate surface-atmosphere science into real-world impacts and innovate industry practices with the best available science. To achieve this, we support the integration and coordination of existing capabilities and resources for enhancing the measurement and quantification of GHG emissions and removals.

Initial Endeavors:

  • Formation of a well-rounded community representing all pertinent stakeholders and experts in climate solutions and GHG emissions trading.
  • Launching collective contributions to workshops and conferences aimed at educating on the significance of direct GHG measurements for equitable climate solutions and emissions trading.
  • Collaborative creation of responses to government policy and funding proposals, co-authoring publications, and piloting projects to test the efficacy of specific methodologies.
  • Future phases will involve efforts towards comprehensive recommendations or protocols, ensuring a balance across environmental, economic, financial, and regulatory aspects to achieve practical and fair climate solutions globally.

This presentation offers a progress report on the latest available tools and other developments in practical technology transfer of flux tools from academia to wider society, the latest adoption examples from FAO to the oil and gas sector, and a progress report on the latest activities by the CarbonDew Community.

 

12 Reduced-Cost Sensor for Direct Evapotranspiration and Sensible Heat Flux Measurements

Poster

George Burba1,2*, Sasha Ivans3, Gerardo Fratini4

1LI-COR, Lincoln, USA. 2Water for Food Global Institute, Lincoln, USA. 3LI-COR, Logan, USA. 4LI-COR, Berlin, Germany

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

Evapotranspiration (ET) plays a vital role in the global water cycle, moving a staggering 500,000 km3 of water annually, with 70,000 km3 occurring over land. This amount surpasses the global water demand of approximately 4,600 km3 per year. By conserving just 5-10% of ET through retention in soil, groundwater, or freshwater bodies, a significant contribution can be made towards solving the global water scarcity issue.

Accurate measurement of ET is essential for effective water management in specific areas. Unfortunately, conventional models such as potential, reference, max, equilibrium, and pan do not achieve the necessary level of accuracy, which is better than 5-10%. However, direct ET measurements using the eddy covariance method provide the required resolution. Historically, the high cost and complexity of this approach have limited its usage primarily to academic research.

To address these challenges, a new cost-effective solution for direct, automated, and real-time ET measurements has been developed. This technology extends the application of eddy covariance ET measurements beyond academia to broader research, regulatory, and commercial domains. The LI-710 sensor is a user-friendly device that measures ET, sensible heat, temperature, humidity, and air pressure every 30 minutes. It is significantly more affordable than typical flux stations, costing 5-10 times less, and consumes 3-15 times less power. Moreover, it can be easily installed and utilized by individuals with limited experience in the field.

The extensive field test results of this innovative technology will be compared with traditional higher-cost research-grade eddy covariance systems. 

 

13 Direct Flux Measurements for Immediate Social Benefits: Clear Explanations, Automated Instruments, Peer-To-Peer Data Sharing, and Weather Station-Inspired Approach

Poster

George Burba*

Water for Food Global Institute, Lincoln, USA. LI-COR, Lincoln, USA. CarbonDew, Lincoln, USA

Session 14. Leveraging Direct Flux Measurements Beyond Academia for Real-World Applications

Continental-scale research infrastructures and flux networks (e.g., AmeriFlux, AsiaFlux, ChinaFlux, ICOS, NEON, OzFlux) alongside smaller GHG flux networks and individual sites, assess CO2, CH4, and other GHG exchange, as well as evapotranspiration (ET), between ecosystems and the atmosphere.

Over four decades, these flux stations have expanded to 2100+ stationary measurement points and various campaign sites. Initially for process-level studies, they now inform long-term climate modeling.

These high-resolution measurements utilize cutting-edge hardware, significantly surpassing typical monitoring methods, commonly applied outside academia. Yet, despite their potential for measuring GHG emissions and ET, these applications rarely extend beyond academia.

Key barriers include the perceived complexity of the method, actual complexity and cost of current instrumentation and site operation, scarcity of geographic data coverage, and a lack of a comprehensive approach focused on using direct flux measurements for immediate societal benefits.

These challenges can be addressed by:

  • Simplifying explanations and offering detailed guides for method understanding.
  • Developing lower-cost simpler-to-use automated flux instrumentation, akin more to being a “flux sensor” than a “flux system”.
  • Facilitating peer-to-peer cross-sharing to reduce data gaps and station setup costs.
  • Adopting an approach inspired by current automated weather stations (AWS) feeding and tuning remotes sensing products and resulting in weather modeling and forecasting.

This presentation aims to catalyze discussions on utilizing flux measurements for practical decision-making applications to benefit society. It seeks to identify current needs, ideas, and examples for leveraging flux data in everyday decision contexts.

 

14 The compatibility of ICOS, NEON, and TERN sampling designs, different camera setups for effective plant area index estimation with digital hemispherical photography

Poster

Jan Pisek1*, Mait Lang1,2, Mihkel Kaha1, Shaohui Zhang3

1University of Tartu, Toravere, Estonia. 2Estonian University of Life Sciences, Tartu, Estonia. 3University of Eastern Finland, Joensuu, Finland

Session 17. Best Practices in the landscape of Research Infrastructures: Cooperation, Co-location and other lessons learned

Environmental monitoring networks such as the Integrated Carbon Observation System (ICOS) in Europe, the National Ecological Observatory Network (NEON) in the U.S., or the Terrestrial Ecosystem Research Network (TERN) in Australia deploy different sampling schemes for in situ measurements. We report on the intercomparison of measurements of canopy gap fraction with different digital hemispherical photography setups adopting ICOS, NEON, and TERN sampling schemes. The test was carried out at the Järvselja Radiation Transfer Model Intercomparison (RAMI) birch stand, near the Station for Measuring Ecosystem-Atmosphere Relations (SMEAR) in Estonia. Results show that spreading out sampling points that cover more of the plot is important for a good representation of the forest as a whole. NEON tower plot layout scheme may be more prone to errors in overall canopy properties estimation than ICOS or TERN due to its compact sampling layout and should always be used in conjunction with its distributed plots. Different camera setups involving different camera operators, camera bodies, lenses, and settings yield slightly varied results, and it is important to ensure that the images are taken in such a way that they would not be over- or underexposed, or out of focus. In conclusion, we always recommend carrying out intercomparison measurements with old and new cameras when devices are upgraded. Our study contributes towards establishing the uncertainty and evaluating potential error budget stemming from collecting in situ measurements using different sampling schemes and camera setups.

 

15 Northern European Forests’ carbon balance and management disturbances: the tale of the direct flux measurements

Oral

Samuli Launiainen1*, Toprak Aslan2

1Natural Resources Institute Finland, Helsinki, Finland. 2Finnish Meteorologica lnstitute, Helsinki, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Northern European Forests’ carbon balance has been monitored by eddy-covariance technique (EC) for nearly three decades. Given that the majority of forests in the region are actively managed, this relentless scientific endeavor is increasingly motivated by identifying the human pressures on forest carbon sink and seeking the climate mitigation potential of alternative forest management regimes. Even though valuable site-specific findings exist, a holistic understanding of forest carbon balances especially in the context of management is missing. Accordingly, here we summarize the means and variability of annual net ecosystem productivity (NEP), gross-primary productivity (GPP) and ecosystem respiration (Re) from more than 40 Northern European temperate, hemi-boreal and boreal forests to: 1) Reveal how well the current and legacy EC-measurements represent the climatic conditions, soils and site fertility types, age and species composition and management regimes; 2) Explore the primary drivers of site-to-site and inter-annual variability, and 3) Conclude what the direct flux measurements reveal on the impacts of management practices (clear-cutting, thinning/partial harvest, fertilization) and disturbance recovery. Finally, we attempt to build a data-driven model for NEP and its components over forest rotation cycles and discuss the pathway how EC-measurements can provide support for planning sustainable forest management.  

 

16 A web-based tool for the validation of Sentinel-2 and Sentinel-3 derived bio‐geophysical products against ICOS terrestrial ecosystems measurements

Oral

Noelle Cremer1*, Dario Papale2,3, Giacomo Nicolini3, Simone Sabbatini3, Luke Brown4, Fabrizio Niro1

1Serco for ESA/ESRIN, Rome, Italy. 2National Research Council - IRET, Porano, Italy. 3CMCC Foundation - Euro-Mediterranean Center on Climate Change, Lecce, Italy. 4University of Salford, Manchester, United Kingdom

Session 17. Best Practices in the landscape of Research Infrastructures: Cooperation, Co-location and other lessons learned

This study aims to demonstrate how ICOS terrestrial ecosystem sites can serve as a network for validating Earth Observation products, thus enhancing spatial and temporal coverage of validation efforts. Focusing on the current ESA optical imaging sensors, the project aims to generate a match-up dataset of Sentinel-2 and Sentinel-3 observations over ICOS ecosystem sites for easing the validation of satellite-derived bio-geophysical products. The objective is to bridge the gap between ecosystem monitoring and satellite remote sensing communities, by facilitating the uptake and exploitation of ICOS data for validation purposes. The project focuses on the validation of a subset of vegetation parameters measured within the existing ICOS network, including key terrestrial Essential Climate Variables, specifically Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) and Leaf Area Index (LAI). As a main outcome of this activity, a set of Jupyter Notebooks on the Terrascope platform is developed and shared within the satellite Cal/Val community, allowing to read the ICOS data, extract the land biophysical products of interest and match them to the corresponding satellite overpasses. Issues such as the spatial representativeness of ICOS sites, the temporal sampling of satellite acquisitions and the inclusion of in-situ uncertainties as a step towards fiducial reference measurements are explored. Statistical metrics are provided within the Notebooks to estimate the suitability of the various sites for the validation at satellite pixel size. This tool is mainly developed to foster the usage of this invaluable ensemble of in-situ reference data for satellite calibration and validation purposes.

 

17 Linking coastal biodiversity, carbon cycling, and climate feedback: hotspots and hot moments

Poster

Nicolas-Xavier Geilfus1*, Kurt Spence1, Märta Brunberg1, Christoph Humborg2, Joanna Norkko1, Alf Norkko1

1University of Helsinki, Hanko, Finland. 2Stockholm University, Stockholm, Sweden

Session 7. Carbon Cycling along the Land Ocean Aquatic Continuum

Biodiversity loss and climate change underscore the critical need for a deeper understanding of their intricate interactions. Coastal ecosystems are highly productive and dynamic in terms of carbon exchange between the ocean and the atmosphere. Due to their potential for carbon capture, those ecosystems hold significant potential as nature-based solution to mitigate climate change. Yet, their effects on carbon cycling and greenhouse gas (GHG) dynamics, including carbon dioxide (CO2) and methane (CH4), remain inadequately understood. This knowledge gap is compounded by substantial heterogeneity in marine biodiversity, further complicating the issue.

In response to these challenges, the CoastClim initiative aims to quantify how spatial variations in biodiversity and ecosystem state, alongside with long-term (i.e., seasonal) and short-term (e.g., marine heatwaves events) variations, trigger the occurrence of hot spots and/or hot moments for interactions between marine biodiversity and GHG dynamics in coastal environments, in the Southern Finland.

At the Tvärminne Zoological Station, we continuously measured at high-resolution seawater concentration of CO2 and CH4 to investigate how seasonal cycles, influencing the type and intensity of primary and secondary production, will impact the production and consumption of GHG in the water column, and thereby affect their air-sea exchange (i.e., hot moments). In August 2023, field measurements performed across a land to sea gradient highlights the presence of hotspots where changes in coastal biodiversity could directly impact the observed surface seawater concentration of GHG, ranging from 160 to 2500 µatm for CO2 and from 20 to 470 nmol/L for CH4.

 

19 Experimental investigation into the footprint of an urban canopy model in a boundary layer wind tunnel

Poster

Hongyuan Jia*, Xiang Wang, Chao Lin, Hideki Kikumoto

The University of Tokyo, Tokyo, Japan

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

As a top-down approach to quantifying the greenhouse gas emissions to the atmosphere from urban areas, the real-time measurements from ground-based monitoring stations employing the eddy covariance technique are commonly coupled with footprint functions to realize the source identification. Although several numerical modeling methods for footprints have been proposed, their reliability in urban applications is not comprehensively validated by experimental data. Besides, it is still necessary to deepen our insight into the footprint features in urban areas through experiment investigations. In this research, we conducted a wind tunnel experiment to measure the concentration and flux footprints in a block-arrayed urban canopy model located in a neutrally stratified boundary layer. The velocity and concentration were measured by an X-probe hot wire anemometer and a fast-response flame ionization detector respectively. The vertical flux was evaluated using the time series data of velocity and concentration. According to the experimental experiments, the relationship between footprint distribution and measurement positions is clarified. The footprint function was found to be unique under different wind directions and cannot be simply approximated by a plume shape. These features can be divided into local and global patterns, which highly depend on building configurations. Moreover, the turbulent contribution ratio to the total flux corresponding to each emission position was calculated. It was found that the turbulent ratio exceeds 70% near the peak of footprint in most cases, which emphasizes the importance of accurate turbulent dispersion modeling in numerical methods.

 

20 Evaluation of the behaviour of O2 and CO2 above a canopy of a forest and its application to further constrain the forest carbon balance

Oral

Kim Faassen1*, Jordi Vilà-Guerau de Arellano1,2, Raquel González-Armas1, Boaz Hilman3, Aleya Kaushik4,5, Bert A. M. Kers6, Ivan Mammarella7, Harro A.J. Meijer6, Wouter Peters1,6, Timo Vesala7,8, Ingrid T. Luijkx1

1Meteorology and Air Quality, Wageningen University and Research, Wageningen, Netherlands. 2Atmospheric Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany. 3Department of Biogeochemical Processes, Max-Planck Institute for Biogeochemistry, Jena, Germany. 4Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, USA. 5NOAA Global Monitoring Laboratory, Boulder, USA. 6University of Groningen, Centre for Isotope Research, Energy and Sustainability Research Institute Groningen, Groningen, Netherlands. 7Institute for Atmospheric and Earth System Research (INAR) / Physics, Faculty of Science, University of Helsinki, Helsinki, Finland. 8INAR/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

The ratio between atmospheric O2:CO2, also called the Exchange Ratio (ER), serves as a valuable tracer for comprehending the carbon cycle at both local and global scales. We investigate the applicability of the ER, focusing on characterizing ERs of biosphere exchange. We have conducted measurements above a boreal forest in Hyytiälä, Finland, during the spring and summer of 2018 and 2019, where we measured O2 and CO2 mole fractions at two heights above the canopy. Integration of the observational data with a conceptual land-atmosphere model reveals that diurnal variations of ERs from single-height O2 and CO2 mole fractions often do not directly reflect forest exchange dynamics. Consequently, careful consideration of the time of day is essential for single-height measurements. The ERs derived from inferred surface fluxes based on the vertical gradient measurements provide a more precise representation of the processes driving the forest exchange. The observed diurnal averaged ER signal from the boreal forest, of 0.83, exhibits temporal fluctuations, challenging the commonly assumed constant biosphere ER value of 1.1. To expand on our diurnal analysis of the ER, we have integrated O2 into the Simple Biosphere Model (SiB4) to explore temporal and spatial variations in the biosphere ERs across different ecosystems. Validation of the model is done with measurements from high-towers where O2 and CO2 mole fractions are measured at multiple heights. This comprehensive study aims to enhance our understanding of biosphere ER variability and its implications as a tracer in carbon cycle research.

 

21 Co-location of measurement sites – what does it mean and what is the added value it provides?

Oral

Niku Kivekäs1*, Elena Saltikoff2, Jaana Bäck3

1ACTRIS ERIC, Helsinki, Finland. 2ICOS ERIC, Helsinki, Finland. 3University of Helsinki, Helsinki, Finland

Session 17. Best Practices in the landscape of Research Infrastructures: Cooperation, Co-location and other lessons learned

ACTRIS, ICOS and eLTER are distributed research infrastructures (RIs) providing data from hundreds of measurement sites spread over Europe and beyond, focusing on different components and processes of the environment. Co-location of the measurement sites of different RIs can provide scientific added value and economic savings compared to a situation where the sites are entirely separated, and this has been recognized by both the scientific community and research infrastructure funders. But what does this co-location actually mean?

From a scientific perspective it is a question of integrating data provided by different RIs and spatial continuity of the measured parameters. Flux and process measurements provide data from very small areas and cannot be extrapolated in a heterogenic environment, therefore requiring very close co-location. Measurements of atmosphere above the canopy level and especially those done via remote sensing can represent conditions and sources averaged over thousands of km2 if the topography is sufficiently homogenous. This means that the measurement sites of different RIs can sometimes be located tens of kms apart and still provide scientific added value due to co-location and potential for up- or downscaling. It depends on the parameters and metadata included and planned use of data. 

From an economic perspective co-location enables use of the same physical infrastructure (buildings, roads, electricity) and maintenance for a larger number of instruments contributing to several RIs. In this case the potential benefits require that the sites are very close to each other, and access to all instruments is agreed between host organizations.

 

22 Resilience of Estuarine Ecosystems to Sediment Dynamics and Climate Variabilityelevation

Poster

Vincent Malului*

Pwani University-Kenya, Kilifi-Kenya, Kenya

Session 15. Science communication and outreach to increase the impact of climate research

Estuaries, as transitional zones between freshwater rivers and marine environments, play a crucial role in coastal ecosystems worldwide. However, they are increasingly vulnerable to the impacts of sediment dynamics and climate variability. This project aims to monitor estuarine sedimentation in correlation to sea-level rise and investigate the resilience of estuarine ecosystems in the face of these challenges.

Through a multidisciplinary approach combining field observations, remote sensing, and modeling techniques, we will assess the long-term changes in sediment deposition patterns and sea-level rise impacts on estuarine environments. Daily monitoring of sea surface temperatures will provide crucial insights into the influence of climate variability on estuarine ecosystems.

The study will focus on a specific estuarine system, employing sediment core analysis to reconstruct historical sedimentation rates and characterize sediment properties. By integrating historical data with contemporary observations, we will identify trends in sediment dynamics and their relationship with sea-level rise. 

Furthermore, we will investigate the response of estuarine biota to these environmental stressors. Biological surveys will assess the abundance and distribution of key species, including benthic organisms and submerged vegetation, providing insights into ecosystem health and adaptation strategies.

Understanding the resilience mechanisms of estuarine ecosystems is essential for effective management and conservation efforts. This research will contribute valuable knowledge to inform coastal resource management practices, including habitat restoration, sediment management, and climate adaptation and control strategies. The project seeks to enhance our ability to mitigate the impacts of environmental change on coastal regions and promote the sustainable stewardship of estuarine habitats.

 

23 Clumped isotope signatures of atmospheric CO2 sources

Poster

Richmal B. Paxton1*, Jan Kaiser1, Alina D. Marca1, Paul F. Dennis1, Penelope A. Pickers1,2, Grant L. Forster1,2,

1Centre for Ocean and Atmospheric Sciences, School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom. 2National Centre for Atmospheric Science, University of East Anglia, Norwich, United Kingdom

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Accurately identifying sources of greenhouse gases is important in order to verify and assist in quantification and modelling of greenhouse gas fluxes. For CO2 emissions, stable isotope measurements of carbon and oxygen are commonly utilised. The use of δ(13C) and δ(18O) as tracers of atmospheric CO2 are, however, complicated by overlaps in isotopic signatures of CO2 sources. The clumped isotope excess, Δ47 (which is a measure of the deviation from the statistical abundance of 13C-18O bonds in CO2) can aid in the distinction of CO2 sources, as the abundance depends on CO2 formation temperature, rather than the abundance of elemental isotopes. 

 

Here we aim to present measurements of Δ47 from a variety of locations. These include a UK cement works, which shows the influence of high temperature combustion processes; Alice Holt Forest (Surrey, UK), which is influenced by plant respiration and photosynthesis; and Weybourne Atmospheric Observatory (Norfolk coast, UK) which is situated close to the North Sea and may be influenced both by local sea-air gas exchange and urban plumes, depending on the air mass origin. Distinct differences between each site allow deriving an improved range of Δ47 signatures from different sources and complement information on the sources of CO2 emissions from the other CO2 stable isotope signatures δ(13C), δ(18O) and Δ(17O).

 

24 Hot Spots and Hot Moments in Greenhouse Gas (CO2, CH4 and N2O) Fluxes in a Diverse Coastal Ecosystem

Oral

Märta Brunberg1*, Christoph Humborg2,1, Alf Norkko1,2, Aki Vähä1,3, Marc Geibel2, Florian Roth2,1

1Tvärminne Zoological Station, University of Helsinki, Helsinki, Finland. 2Baltic Sea Centre, Stockholm University, Stockholm, Sweden. 3Institute of Atmospheric and Earth System Research / Physics, Faculty of Science, University of Helsinki, Helsinki, Finland

Session 7. Carbon Cycling along the Land Ocean Aquatic Continuum

Coastal ecosystems have high rates of organic matter (OM) accumulation and can act as efficient net sinks of carbon dioxide (CO2) from the atmosphere, which makes them suitable for nature-based climate change mitigation. At the same time, concurrent natural emissions of methane (CH4) and nitrous oxide (N2O) produced during OM degradation may impede the net radiative forcing benefit. Here, we simultaneously measured CO2, CH4, and N2O surface water concentrations, and calculated their associated sea-air emissions, using an underway survey technique in a 28 ha semi-enclosed bay in the Baltic Sea with various vegetated and unvegetated bottom substrates during seven campaigns from October 2021 to August 2022. Bottom habitats included rocks with macroalgae, and soft sediments with or without various macrophytes, such as Zostera marina and Myriophyllum spicatum. We report net greenhouse gas (GHG) fluxes from surface waters ranging from -874.5 mg CO2eq m-2 d-1 in May (net sink) to 70.9 mg CO2eq m-2 d-1 in December (net source), with large temporal and spatial variability. Additionally, we show that the highest emissions generally occurred in sheltered and vegetated areas of the bay. Throughout the year, net uptake of CO2 by vegetation was offset by 5 to 44 % by concurrent CH4 and N2O emissions. Coastal vegetated bays may indeed function as net sinks of atmospheric CO2eq over an annual cycle, but concurrent CH4 and N2O emissions, and the natural heterogeneity of such fluxes should be taken into account to establish informed climate change mitigation strategies.

 

25 International Governance of Marine Carbon Dioxide Removal: Bridging the Divide Between the Global Climate Regime and the Global Ocean Governance Regime

Poster

Roman Webb*

Columbia Law School, New York, USA. Columbia Climate School, New York, USA

Session 8. Enhancing the ocean carbon sink: the science, verification, and governance of marine-based carbon dioxide removal (mCDR)

With the impacts of climate change intensifying and progress in reducing emissions continuing to lag, the parties to the Paris Agreement are increasingly looking at greenhouse gas removal as a climate change mitigation tool. Marine-based carbon dioxide removal (mCDR) has received particular attention under the Paris Agreement recently. At a meeting in late 2023, the parties to the Paris Agreement stressed “the importance of conserving, protecting and restoring . . . marine ecosystems” as carbon sinks and called for “accelerating” carbon removal. Just a few weeks earlier, however, the parties to another set of international agreements – the London Convention and Protocol – had proposed new restrictions on mCDR. In justifying the restrictions, the parties rightly noted that there is currently limited understanding of mCDR techniques, and raised valid concerns about the risks they present. The parties recognized the need for further research into mCDR but indicated that only “legitimate scientific research” should be allowed. While this approach may have theoretical appeal, in practice, determining what research is legitimate is proving difficult. There are growing concerns that restrictions adopted under the London Convention / Protocol will block research needed to determine what (if any) role mCDR might play in achieving the Paris Agreement’s goals. This presentation will explore the reasons behind, and implications of, the growing disconnect between the two treaty regimes. It will also explore options for promoting greater coherence in international governance of mCDR, including the possibility of using the new High Seas Treaty to comprehensively regulate mCDR.

 

26 MISO - Autonomous in-situ observation platform for hard-to-reach areas

Poster

Lona van Delden1*, Tuan Vu Cao2, Torbjørn Heltne2, Claire Treat1

1AWI, Potsdam, Germany. 2NILU, Kjeller, Norway

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

MISO will develop and demonstrate an autonomous in-situ observation platform for hard-to-reach areas, such as the Arctic and wetlands overall. We are working on a new design to detect and quantify CO2 and CH4 fluxes, using a combination of stationary and mobile (drone) solutions. Our system will require minimum on-site intervention when deployed. In the MISO project, the AWI team is leading the development of the GHG flux chambers and leading the proof of concept for deployment in wetland and Arctic ecosystems. The new chamber design is focusing on lower cost, low weight and low energy consumption. Each self-contained chamber includes an integrated MISO sensor, self-power, and innovative communication solutions in rural areas.

 

27 Consequences of intense drought on CO2 & CH4 fluxes and evapotranspiration rates of the reed ecosystem at Lake Neusiedl

Poster

Pamela Baur*

University of Vienna, Vienna, Austria

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Wetlands with reeds (Phragmites australis) are widely recognized as strong carbon (C) sinks due to the high productivity of reed and its fixation in the soil. Lake Neusiedl is an internationally important wetland (Ramsar, UNESCO World Heritage Site) that had been affected by droughts since mid-2015. However, the impact of drought on reed-dominated wetlands and the contribution of Central European reed ecosystems as a source of greenhouse gases (GHG) are not well understood. The aim of this multi-year study (mid-2018 to 2022) was to investigate the drought-influenced C & water fluxes and their drivers in the reed ecosystem of this subsaline lake. We used eddy covariance technique to quantify GHG exchange between reed ecosystem & atmosphere and vegetation indices to account for reed growth.

The results showed a 76% decrease in CH4 emissions from 9.2 g C m-2 a-1 (2019) to 2.2 g C m-2 a-1 (2022), mainly due to the falling water level and the associated drying out of the reed belt. Initially, net CO2 emissions decreased by 85% from 181 g C m-2 a-1 (2019) to 27 g C m-2 a-1 (2021), as the reed grew into formerly water-covered areas within the reed belt. In 2022, however, net CO2 emissions increased to twice the 2019 level due to the consequence of the sharp drop in sediment water content from 65 to 32 Vol-% in mid-2022.

Overall, drought led to a decoupling of the reed belt from the lake and turned the wetland into a strong C source.

 

28 Carbon flux responses of Alpine ecosystems to combined future climate drivers: Exploring different climate scenarios

Poster

Federica D'Alò1*, Olga Gavrichkova1, Carlotta Volterrani1, Maurizio Sarti1, Alexandru Milcu2, Sebastien Devidal2, Enrico Brugnoli1, Angela Augusti1

1; Institute of Research on Terrestrial Ecosystems, National Research Council, Porano, Italy. 2Montpellier European Ecotron, Univ Montpellier, CNRS, Montferrier-Sur-Lez, France

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

During the 21st century, alpine areas are experiencing warming above the global average, making them more sensitive to climate change, with potentially dramatic effects on the release of significant quantities of CO2. Indeed, an expected impact of climate change is the alteration of the balance between carbon assimilation, through photosynthesis, in plant biomass and storage in soils, and its release to the atmosphere via respiration. To predict the effects of climate change on CO2 fluxes, monoliths were collected from an alpine ecosystem (2500m a.s.l.) in the Mont Blanc area (Val Veny, Courmayeur, Italy) and transferred to the Montpellier European Ecotron (CNRS, France) for climate manipulation experiments. Monoliths were exposed to current (~ 420ppm CO2, Control), and 2 future climate scenarios (~ 550ppm CO2 and ~ 800ppm CO2, according to RCP 4.5 and RCP 8.5, respectively) forecasted for 2070. The Ecotron’s experimental chambers allowed to manipulate different climate variables, such as temperature, precipitation, relative humidity, radiation, and COconcentration, simultaneously. To assess flux responses, measurements of gross primary productivity (GPP), ecosystem respiration (Reco), and net ecosystem exchange (NEE) were performed twice a week over the summer period. While the differences in terms of fluxes between Control and RCP 4.5 were small, for the RCP 8.5 a greater GPP and more noticeable Reco were observed compared to the other scenarios. Nevertheless, the NEE in RCP 8.5 showed that the alpine ecosystem could work as a sink compared to the other two scenarios, likely attributed to a substantial increase in green canopy.

 

29 Metrological concepts applied to total alkalinity measurements in support of ocean alkalinity enhancement assessment

Poster

Gaëlle Capitaine1,2*, Paola Fisicaro2, Thibaut Wagener1

1MIO, Marseille, France. 2LNE, Paris, France

Session 8. Enhancing the ocean carbon sink: the science, verification, and governance of marine-based carbon dioxide removal (mCDR)

Ocean alkalinity enhancement (OAE), a method considered for marine Carbon Dioxide Removal, involves increasing seawater alkalinity by adding alkaline substances as crushed rocks or dissolved compounds. This technique aims to increase CO2 absorption of the ocean, but also to mitigate ocean acidification.

Prior to large-scale implementation of OAE, establishing a robust Monitoring, Reporting, and Verification system is crucial. It is advisable to monitor various variables, including total alkalinity (TA) together with at least one additional parameter of the carbonate system, to assess the OAE effectiveness. TA measurements serve multiple purposes, including computing essential carbonate chemistry parameters, quantifying background alkalinity, and confirming the efficient addition of alkalinity. Therefore, applying metrological concepts as validation of measurement procedures, uncertainty quantification, and metrological traceability, is imperative.

Although existing reference materials (RMs) for TA measurements offer valuable support to the oceanographic community, they lack complete traceability and thorough uncertainty assessment. To address this, a reference material made in artificial seawater, characterized using an SI-traceable reference method, and with rigorously quantified uncertainty is being developed. Distributing this RM alongside a natural seawater sample, as Scripps’ one, could enhance the accuracy of TA results. The presentation will include results from an inter-laboratory comparison conducted on this reference material and propose traceability route, along with a preliminary estimation of the open-cell multi-step potentiometric titration measurement method of TA. The implications of this work in providing reliable TA data for assessing OAE and, more broadly, the role of NMI services in ensuring reliable ocean observation, will finally be discussed.

 

30 Local-level CO2 emissions and their spatial variability in two contrasting cities Helsinki and Beijing

Oral

Leena Järvi*

University of Helsinki, Helsinki, Finland

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Comprehensive understanding of CO2 emissions and sinks are needed to support climate actions in cities. Atmospheric observations have the challenge of measuring the total CO2 concentration or flux providing little information on the detailed urban CO2 flux dynamics. Here the role of bottom-up approaches in estimating the emissions strengths and spatial distributions become important as they can provide detailed information on emission and sink hotspots. In this study, the Surface Urban Energy and Water Balance Scheme (SUEWS) is used to examine the distribution of local-level direct CO2 emissions and biogenic emissions and sinks in Helsinki (Finland) and Beijing (China). The main aims are to 1) quantify the local emissions and their spatial variability, and 2) examine the strength of the emissions and biogenic sinks as a function of urban land cover. In both cities, traffic is major contributor to the local-level emissions varying from 38% to 42%. In Beijing, emissions from local building heating were almost equal to the traffic emissions, whereas in Helsinki only minor contribution was seen due to extensive district heating. Human metabolism contributed 58% and 13% in Helsinki and Beijing, respectively showing its importance in urban carbon dynamics. Largest CO2 sinks were seen in natural forested areas in Helsinki whereas in Beijing the forest in montane areas remained weaker sink compared to urban forests due to lower air temperatures. Vegetation within the built neighborhoods also have a significant impact on net CO2 sinks, contributing almost half of the net COsinks in Helsinki. 

 

31 Summer greenhouse gases spatial variability from Southern Greenland Fjords to subpolar North Atlantic Ocean

Poster

Coraline Leseurre1*, Bruno Delille2, Roobaert Alizée1, Wieter Boone1, Odile Crabeck2, Leandro Ponsoni1, Hannelore Theetaert1, Michiel T'Jampens1, Silke Verbrugge1, Thanos Gkritzalis1

1Flanders Marine Institute, VLIZ, Ostende, Belgium. 2Chemical Oceanography Unit, ULiège, Liège, Belgium

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Since the beginning of the industrial era, the atmospheric greenhouse gases (GHG) have increased continuously (around +50% for carbon dioxide (CO2) and +150% for methane (CH4), for the two most important), causing the current climate change. In November 2023, the World Meteorological Organization (WMO) highlighted once again there are still significant uncertainties about the carbon cycle and its fluxes, and stressed the importance to follow the non-CO2 GHG with greater global warming potential. 

The subpolar North Atlantic Ocean is a major CO2 sink, whereas the continental shelf and fjords show more spatial-temporal variability and poor regional coverage of sea-air CO2 flux data due to the lack of in-situ observational data. While surface seawaters are naturally supersaturated in CH4, the Arctic region (including Southern Greenland fjords) is subject to rapid warming and, therefore, is susceptible to substantial CH4 release into the atmosphere, further exacerbating global warming.

To improve our knowledge, it is essential to increase observational efforts to reduce uncertainties on the ocean CO2 sink and monitoring CH4 levels in high-latitude surface waters where changes have already been observed. To do so, we measured CO2 and CH4 concentrations and calculated their fluxes, in surface water during a summer cruise (July-August 2023) conducted on board the RV Belgica in the subpolar North Atlantic Ocean, between Iceland and Southern Greenland Fjords. The data were obtained using a custom-made air-water equilibration system, that was connected to the vessel’s non-toxic seawater supply (equilibrator and Cavity Ring Down Spectrometer) and discrete sampling.

 

32 URBFLUX project: Monitoring urban and peri-urban CO2 and energy fluxes in the city of Valencia.

Poster

Arnaud Carrara*, Ramon Lopez Jimenez, Vicent Calatayud

Fundacion Centro de Estudios Ambientales del Mediterraneo (CEAM), Paterna, Spain

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

The project URBFLUX focuses on the city of Valencia as an “urban laboratory”, with the general objective to provide science-based information that can be used by municipalities and other stakeholders to mitigate CO2 emissions, reduce air pollution, and regulate temperature in the urban environment by using green infrastructure. One specific objective is to investigate the urban CO2 emissions and sinks of the urban area of Valencia. In the frame of the project, three eddy covariance (EC) stations were deployed in 2023, in an urban area, an urban vegetated pedestrian area, and in a protected periurban area of horticultural crops. These stations will produce relevant observations on the dynamic of CO2 fluxes in urban and peri-urban environment, but also on sensible and latent heat fluxes, to better understand the role of vegetation in regulating air temperature at both local and city scale. Another specific objective is to estimate ecosystem services provided by tree vegetation at the scale of Valencia city using the i-TREE software tool model. The outputs of the model will be air pollution removal, BVOCs emissions, gross and net annual carbon sequestration, trees sequestering most net carbon in the city, and energy savings by trees. We present an overview of the project and preliminary results from CO2 fluxes measurements.

 

33 Temporal and vertical variation of in-situ methane turnover from stable isotope studies at a boreal peatland

Oral

Xuefei Li1*, Janne Rinne2, Timo Vesala1,3

1Institute for Atmospheric and Earth System Research (INAR)/Physics, University of Helsinki, Helsinki, Finland. 2Natural Resources Institute Finland, Helsinki, Finland. 3Institute for Atmospheric and Earth System Research (INAR)/Forest Sciences, University of Helsinki, Helsinki, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Boreal peatlands emit substantial amounts of CH4 to the atmosphere. Understanding the dynamics of the co-occuring and seasonally varying processes underlying CH4 emissions remains a challenge. Stable isotope signatures of the CH4 in soil pore water and emitted CH4 can provide valuable insight on these processes.

We conducted a systematic study using on-line stable isotope measurements to understand the annual cycle of CH4 turnover in a typical boreal peatland (Siikaneva fen) in Southern Finland. We conducted continuous measurements of dissolved CH4 concentrations and its δ13C natural abundance signatures at 10, 30 and 50cm belowground. In addition, measurements at 40cm above peatland surface were used to estimate ecosystem-scale average δ13C value of the emitted CH4.

Results showed systematic differences in the vertical profiles of CH4 concentrations and its δ13C values between winter and summer. CH4 concentrations from all the depths were higher in summer than in winter. The highest concentration of CH4 was observed at 30cm depth. δ13C values of CH4 in peat were highest in the deeper layer and lowest in the surface layer in winter, while the opposite pattern was found in summer. As expected, the CH4 production pathway shifted towards acetoclastic methanogenesis during the winter-summer transition. In winter, the δ13C values from emitted CH4 were higher than those from the soil indicating CH4 oxidation, while in summer the opposite was found due to CH4 diffusive plant transport. We observed hysteresis-like behavior between CHconcentration and δ13C indicating time-lagged CHproduction to soil temperature and substrate availability.

 

34 Modelling the CO2 transport through secondary circulations

Oral

Luise Wanner1*, Martin Jung2, Sreenath Paleri3,4, Brian Butterworth5,6, Ankur Desai7, Matthias Sühring8,9, Matthias Mauder10,11

1TUD Dresden University of Technology, Dresden, Germany. 2Max Planck Institute for Biogeochemistry, Jena, Germany. 3University of Oklahoma, Norman (OK), USA. 4NOAA/Air Resources Laboratory, Oak Ridge (TN), USA. 5University of Colorado Boulder, Boulder (CO), USA. 6National Oceanic and Atmospheric Administration, Boulder (CO), USA. 7University of Wisconsin-Madison, Madison (WI), USA. 8Leibniz Universität Hannover, Hannover, Germany. 9Pecanode GmbH, Goslar, Germany. 10TUD Dresden Technical University, Dresden, Germany. 11Karlsruhe Institute of Technology, Karlsruhe, Germany

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

The investigation of the systematic energy balance gap has indicated that a part of the energy transport is not carried out by small-scale turbulence but by so called secondary circulations, which are large eddies spanning the entire atmospheric boundary layer vertically. The share of energy transported by secondary circulations is especially large over thermally heterogeneous surfaces and cannot be captured by typical 30-minute single-tower eddy covariance measurements by definition. It is highly probable that these secondary circulations also transport other substances, such as CO2, which results in an underestimation of the CO2 fluxes by single-tower eddy covariance measurements. The transport through secondary circulations can be quantified as dispersive fluxes. We present a novel model that is able to predict the dispersive CO2 flux, which is an extension of an already existing model of the dispersive sensible and latent heat fluxes. The model has been developed by combining a machine-learning approach with a large set of idealized large-eddy simulations covering different surface-heterogeneity scales and stability regimes and it can be applied to 30-minute eddy covariance measurements without additional instrumentation. The application of the models for sensible and latent dispersive heat fluxes to real-world measurements and realistic large-eddy simulations from the CHEESEHEAD19 project indicate a good agreement. Here we show that the approach is transferable to dispersive CO2 fluxes and test the model on the realistic CHEESEHEAD19 large-eddy simulations.

 

35 Design, operation, and insights from Zürich city’s mid- and low-cost ICOS Cities CO2 sensor network

Poster

Stuart Grange1,2*, Pascal Rubli1, Andrea Fischer1, Christoph Hueglin1, Nikolai Ponomarev1, Dominik Brunner1, Lukas Emmenegger1

1Empa, Dübendorf, Switzerland. 2University of York, York, United Kingdom

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

A carbon dioxide (CO2) sensor network was deployed across the city of Zürich (Switzerland) in mid-2022 as a component of the ICOS Cities project. ICOS Cities has the overall objective of quantifying CO2 emissions in urban areas and to assess a wide range of methods to achieve this goal. The CO2 sensor network is composed of 180 nondispersive infrared (NDIR) sensors at two broad cost points labelled mid- and low-cost. The mid-cost sensors are generally installed with inlets at roof level and are deployed with reference gases to enable the sensors to achieve very good levels of measurement performance (RMSE of less than 1.5 ppm and biases within ±1 ppm at hourly resolution). The low-cost sensors are an order of magnitude cheaper, are generally installed at street level, and their calibration instability over time, i.e., drift, is addressed with network calibration methods that utilise the trusted mid-cost sensor observations. Although the main utility of the sensor network is to provide observations for atmospheric inversion modelling systems, the sensor network itself provides value by illuminating Zürich city's CO2 gradients and source-sink dynamics. For example, the city's CO2 spatial gradient is between 30 and 35 ppm depending on the season, the city's regional background CO2 is highly variable, and biogenic emissions combined with very stable nocturnal boundary layer processes can drive peak CO2 mole fractions over 700 ppm in the very early morning at some monitoring sites. The design, operation, and results of the sensor network will be further detailed and presented.

 

36 Fossil Fuel CO2 gradients and emissions in London observed using Radiocarbon (14C) Measurements

Oral

Fang Liu1*, Mathias Lanoiselle2, Xiaomei Xu3, Heather Graven1

1Imperial College London, London, United Kingdom. 2Royal Holloway University of London, London, United Kingdom. 3University of California Irvine, California, USA

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Urban areas accommodate over half of the global population and contribute more than 60% to greenhouse gas emissions. The increase in greenhouse gases, notably CO2, primarily stems from fossil fuel emissions. However, accurately quantifying fossil CO2 emissions in urban regions remains challenging due to complex and varied sources, including anthropogenic and biogenic factors, and spatiotemporal variability. Radiocarbon (14C) measurements in atmospheric CO2 provide a method to differentiate between fossil and non-fossil sources, as fossil carbon lacks 14C. At Imperial College London, we conducted 14C measurements to assess fossil fuel COemissions and biospheric CO2 fluxes at three sites across London between 2022 and 2023. We used a sampling system that adsorbs CO2 onto a molecular sieve trap after removing water, with the sampled CO2 desorbed through heating for measurement. The measurement uncertainty is below 2‰. We find that the fossil fuel COemissions exhibited the highest levels during the winter months for all the three sites across London, whereas biospheric COexhibited the lowest values during the spring-summer seasons. The ongoing warming trend in spring enhanced the uptake of photosynthetic CO2, leading to the most significant seasonal shift in net ecosystem CO2 exchange.

 

37 Leveraging In Situ Data for Climate and Environmental Policy Support

Poster

Adolphus Ifeka*

Federal University of Technology, Akure, Nigeria

Session 13. In situ data for climate and other environmental services and policy support

Using in situ data is essential for sustaining environmental services and guiding policy decisions in the age of rapidly increasing climate change and environmental degradation. In order to incorporate in situ data into frameworks for environmental and climate policy, this article highlights important findings and methods from the fields of Meteorology and Climate science. 
    

This study examines the value of in situ data in improving the precision and dependability of climate models, enabling efficient environmental monitoring, and assisting with the development of evidence-based policy. It draws on my professional experience with the Nigerian Meteorological Agency. This report emphasizes the transformational potential of in situ data in solving modern environmental concerns by integrating empirical facts and best practices. 
    

One of the main topics covered is how to incorporate in situ data into climate change mitigation.

Keywords: In situ data, Climate change, Environmental policy, Sustainability, Policy support.

 

38 Photosynthetic leaf-level temperature response of dominant tree species in a humid lowland tropical forest of the Congo Basin

Poster

Thomas Sibret1*, Marc Peaucelle2, Kristine Crous3, Felicien Meunier1, Ivan Janssens4, Marijn Bauters1, Hans Verbeeck1, Pascal Boeckx1

1UGent, Gent, Belgium. 2INRAE, Bordeaux, France. 3Western Sydney University, Penrith, Australia. 4UAntwerp, Antwerp, Belgium

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Tropical forests, crucial components of the global carbon cycle, are increasingly threatened by climate change. Recent studies emphasize the concerning trend of tropical tree species approaching their thermal limits, resulting in a decrease in net carbon uptake above current ambient temperatures. These findings, combined with the historically stable climate of tropical regions, raise concerns about these forests' ability to adapt to rapid temperature changes and the growing frequency of climate extremes.

Moreover, the influence of canopy position on temperature-response of photosynthesis remains poorly understood, despite its potential significance in shaping ecosystem dynamics. Variations in physiological and morphological traits across canopy layers suggest nuanced responses to rising temperatures, with implications for species distributions and forest resilience.

To address these knowledge gaps, we conducted field-based leaf chamber measurements in the Congo Basin, housing the world's second-largest tropical forest, at the CongoFlux research site [Station ID: CD-Ygb]. Leveraging the presence of an ICOS flux tower enables the comparison of our leaf-level data with ecosystem-level measurements, facilitating comprehensive analyses from individual species to ecosystem-scale processes.

Doing so, our study aims to provide the first comprehensive dataset on leaf-level photosynthetic parameters for dominant tree species in an African lowland tropical forest. By quantifying interspecific variation in photosynthetic capacity and exploring the influence of plant guilds, species, and vertical canopy position, we seek to enhance our understanding of forest dynamics and resilience to temperature changes.

 

39 Advances and challenges of Solar-Induced chlorophyll Fluorescence (SIF) in understanding Arctic-Boreal carbon uptake across spatial-temporal scales: A review

Poster

Rui Cheng*

University of Minnesota, St Paul, USA. Massachusetts Institute of Technology, Cambridge, USA

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Solar-Induced chlorophyll Fluorescence (SIF), a good proxy for vegetation CO2 uptake, has been broadly utilized to assess vegetation dynamics and carbon uptake at the global scale. However, the full potential and limitations of SIF in the Arctic-Boreal region have not been explored. Therefore, this presentation summarizes a recently published review paper (doi: 10.1007/s40641-024-00194-8) of the latest insights into Arctic-Boreal carbon uptake through SIF analyses, underscoring the advances and challenges of SIF in solving emergent unknowns in this region. We will present evidence that cross-scale SIF measurements complement each other, offering valuable perspectives on Arctic-Boreal ecosystems, such as vegetation phenology, carbon uptake, carbon-water coupling, and ecosystem responses to disturbances. By incorporating SIF into land surface modeling, the understanding of Arctic-Boreal changes and their climate drivers can be mechanistically enhanced, providing critical insights into the changes of Arctic-Boreal ecosystems under global warming. While SIF measurements are more abundant and with finer spatiotemporal resolutions on the global scale, it is important to note that the coverage of these measurements is still limited and uneven in the Arctic-Boreal region, which addresses the importance of fostering a SIF network providing long-term and continuous measurements across spatial scales.

 

40 Towards 2060 Carbon Neutrality: Air Pollution And Health Co-Benefits Of Climate Change Mitigation Of The Gba

Poster

Chao REN1*, Edward NG2

1Faculty of Architecture, The University of Hong Kong, Pokfulam, Hong Kong. 2School of Architecture, The Chinese University of Hong Kong, Shatin, Hong Kong

Session 15. Science communication and outreach to increase the impact of climate research

Climate change and air pollution are interrelated. Climate mitigation could bring multiple benefits, among which air pollution-related health cobenefits are the most important. With its carbon emissions expected to peak around 2030, the Chinese government strives to reach the ‘carbon neutral’ goal for the whole nation by 2060. Guangdong-Hong Kong-Macau Greater Bay Area (GBA) is now the biggest rapidly developing economic and industrial region in China, with a population of 22 million. Its intensive industry and human activities have a significant influence on the national economy but at the cost of local air quality and intensifying climate change with substantial greenhouse gas (GHG) emissions. Local municipal and provincial governments of the GBA have pledged recently to achieve carbon neutrality by 2060. Concrete measures and pathways to achieve this ambitious target have yet to be made. Thus, it is important to explore the potential climate change mitigation pathways to 2060 carbon neutrality and to have a comprehensive assessment of air quality and health co-benefits of the implementation of climate change mitigation pathways for developing the optimised climate policy and a collective action plan for the local governments of the GBA to reach a win-win result. The study aims to link the climate change mitigation, air pollution reduction and health co-benefits together to explore the optimal pathways to achieve the targeted carbon neutrality in 2060. 

 

41 The ocean gliders capacity to estimate the air-sea CO2 flux: from machine learning tools to innovative sensors

Oral

Laurent Coppola1*, Edouard Leymarie2, Paco Stil1, Felix Margirier3, Socratis Loucaides4, Janne-Markus Rintala5

1Sorbonne University, Villefranche-sur-Mer, France. 2CNRS, Villefranche-sur-Mer, France. 3ALSEAMAR, Rousset, France. 4NOC, Southampton, United Kingdom. 5ICOS ERIC, Helsinki, Finland

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

The ocean is a major sink of anthropogenic CO2 (Friedlingstein et al., 2020). Estimates of the ocean's carbon sink are derived from global ocean biogeochemical models (Hauck et al., 2020) and reconstructions based on data concerning surface ocean partial pressures of CO2. The Surface Ocean CO2 Atlas (SOCAT) (Bakker et al., 2016) primarily relies on data obtained from underway sampling systems aboard voluntary observing ships. However, the limited coverage of data and the absence of observations throughout the entire seasonal cycle pose challenges to mapping methods, resulting in noisy reconstructions of surface ocean pCO2 (Denvil-Sommer et al., 2019). In response, the emergence of deep learning methods offers an alternative for predicting carbonate system variables (Sauzède et al., 2016; Fourrier et al., 2020). Nonetheless, fostering the advancement of robust and dependable technologies is imperative for enhancing observing systems. In this context, the European project GEORGE (grant 101094716) aims to develop new technologies to improve ocean observations that will represent the next level of long-term autonomous ocean observations. It will improve the coverage, continuity and spatio-temporal resolution of marine observations based on a variety of platforms operated by three ERICs (EMSO, ICOS and Euro-Argo). We will focus here on the development and integration of new sensors for carbonate system measurements (TA, TC, pH and pCO2). Of particular interest will be ocean glider-operated measurements and pCO2 and pH sensors in the Ligurian Sea, accompanied by acoustic measurements for better estimation of wind speed, an important parameter in CO2 air-sea flux calculations. 

 

42 Surface CO2 system dynamics along the western Mediterranean Sea based on high-frequency measurements from a Volunteer Observing Ship.

Oral

David Curbelo-Hernandez, David Gonzalez-Santana, Aridane Gonzalez-Gonzalez, J Magdalena Santana Casiano, Melchor Gonzalez-Davila*

Instituto de Oceanografía y Cambio Global. Universidad de Las Palmas de Gran Canaria, LAS PALMAS DE GRAN CANARIA, Spain

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

The spatio-temporal variations in the surface CO2 system along the western boundary of the Mediterranean Sea is evaluated. A high-resolution physicochemical dataset spanning 5 years (2019-2024) was built through automatically underway monitoring lead by the Surface Ocean Observation Platform aboard the Volunteer Observing Ship MV JONA SOPHIE ( ICOS SOOP CanOA-VOS). The ongoing warming of the surface Mediterranean was documented based on observations in this area. The sea surface temperature (SST) increased by 0.38±0.05 ºC yr-1 in the Alboran Sea and 0.30±0.04 ºC yr-1 along the eastern Iberian margin (p-values<0.01), which represent an acceleration in warming of 87.9% and 78.0%, respectively, compared to 2000-2019. These rates were found to be led by a rapidly increment in SST during summer, which contributed to modify the temporal evolution of the surface CO2 fugacity (fCO2,sw) and pH. Its interannual rates of change were 4.8 ± 0.6 µatm yr-1 and -0.005±0.001 units yr-1 in the Alboran Sea and 5.2 ± 0.4 µatm yr-1 and -0.006±0.001 units yr-1 in the eastern Iberian margin (p-values<0.01). The rise in fCO2,sw was governed by SST fluctuations (contributing by 59.1-63.0%) and compensated by variations in total inorganic carbon (27.9-31-6%). Both subregions behaved as a net atmospheric CO2 sink (average values -0.80±0.01 and -0.57±0.01 mol m2 yr-1). However, warming is favouring the outgassing during late summer and reducing by a 50% the annual uptake of CO2 from the atmosphere during the studied period (-0.52 mol m2 yr-1 in 2023 versus -1.02 mol m2 yr-1 in 2019).

 

43 Shoots of mature European beech as important sinks for atmospheric nitrous oxide (N2O)

Oral

Katerina Machacova1*, Thomas Schindler1,2, Laëtitia Bréchet3, Ülo Mander2,1, Thorsten E. E. Grams4

1Department of Ecosystem Trace Gas Exchange, Global Change Research Institute of the Czech Academy of Sciences, Brno, Czech Republic. 2Department of Geography, Institute of Ecology & Earth Sciences, University of Tartu, Tartu, Estonia. 3INRAE, UMR EcoFoG, CNRS, Cirad, AgroParisTech, Université des Antilles, Université de Guyane, Kourou, France. 4Department of Life Science Systems, School of Life Sciences, Technical University of Munich, Freising, Germany

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Tree stems are known to emit but also consume nitrous oxide (N2O) from the atmosphere. Even though tree leaves dominate the tree surface area, they have been entirely excluded from field N2O flux measurements, and their role in forest N2O exchange is still unknown. We investigated the contribution of leaf fluxes to the forest N2O exchange. We determined the N2O exchange of stems and shoots (i.e. terminal branches including leaves) of mature European beech (Fagus sylvatica), and adjacent forest floor in a typical temperate upland forest in Southern Germany, using static chamber systems, portable greenhouse gas analyser and scaffold towers to reach the top of tree crowns. The beech stems, and especially the investigated shoots acted as net N2O sinks (−0.254 ± 0.827 µg N2O m−2 stem area h−1 and −4.54 ± 1.53 µg N2O m−2 leaf area h−1, respectively), while the forest floor was a net source (2.41 ± 1.08 µg N2O m−2 soil area h−1). Our pioneering study revealed a key mechanism at the net forest ecosystem N2O exchange: never-studied tree shoots can be substantial N2O sinks. Our results clearly show that excluding tree leaves from forest N2O flux measurements could lead to substantial uncertainties in the total N2O exchange between trees and the atmosphere, altering global forest greenhouse gas flux inventories.

 

44 Flux measurements of carbon monoxide by eddy covariance over two pristine wetlands in high latitudes

Poster

Asta Laasonen1*, Kukka-Maaria Kohonen1,2, Erik Lundin3, Alexander Meire3, Ivan Mammarella1

1Institute for Atmospheric and Earth System Research (INAR)/ Physics, Faculty of Science, University of Helsinki, Helsinki, Finland. 2Department of Environmental Systems Science, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland. 3Swedish Polar Research Secretariat, Abisko Scientifc Research Station, Abisko, Sweden

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Carbon monoxide (CO) plays a major role in atmospheric chemistry, being the largest sink of hydroxyl radical OH, which is the key oxidant in the atmosphere and determines the distributions of many other chemical species, including methane and ozone. Additionally, CO serves as an energy source for various soil microbes, playing a significant role in the carbon cycle.  

In this study, we present the first eddy covariance time series of CO fluxes measured over two pristine wetlands. The study sites, Siikaneva fen in southern Finland and Abisko-Stordalen Palsa-bog in northern Sweden, are both classified as ICOS class 2 Ecosystem Stations. Measurements were conducted during the years 2019 and 2022-2023, respectively. 

We observed systematic diurnal and seasonal cycles in the fluxes, with emissions during the daytime and near-zero fluxes or uptake during the night-time at both sites. Both sites were net CO sources during the snow-free periods, with greater spatial and temporal variability in fluxes observed in Stordalen than in Siikaneva. The CO emissions were driven by radiation and temperature, related to photo- and thermal degradation of organic matter. In Stordalen systematic soil consumption was observed in nighttime fluxes, whereas consumption was not observed in Siikaneva. The consumption in Stordalen was higher in the drier part of the mire, likely controlled by differences in soil properties.  

Despite the relatively small amount of carbon released as CO from wetlands, understanding the CO flux dynamics plays a crucial role in understanding soil processes and atmospheric chemistry. 

 

46 Addressing challenges in representing inter-annual variability of gross primary productivity fluxes using robust empirical and theory-based models

Oral

Ranit De1,2*, Shanning Bao1,3, Sujan Koirala1, Alexander Brenning2,4, Markus Reichstein1,4, Nuno Carvalhais1,4,5

1Department for Biogeochemical Integration, Max-Planck-Institute for Biogeochemistry, 07745 Jena, Germany. 2Department of Geography, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany. 3National Space Science Center, Chinese Academy of Sciences, 100190 Beijing, China. 4ELLIS Unit Jena, Jena, Germany. 5CENSE, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Terrestrial vegetation is crucial in the carbon cycle, primarily for mediating atmospheric CO2 fluxes through photosynthesis. The inter-annual variation (IAV) of gross primary production (GPP) is highly correlated with peak GPP frequency in diurnal cycles, yet biogeochemical models often fail to simulate these peaks. Here, we compare a light use efficiency (LUE) model and an eco-evolutionary optimality-based P-model to simulate the IAV of GPP. Both models estimate GPP at sub-daily scale, and are optimized for each site-year, site, plant functional type, and globally, followed by an evaluation at different temporal resolutions across 198 eddy-covariance sites of diverse climate-vegetation types. Hourly model (site-year optimization) evaluations show significantly higher performance (Nash-Sutcliffe efficiency, viz. NSE ≥ 0.6 for 93% and 86% of sites for LUE and P-model respectively) compared to yearly aggregated evaluations (NSE ≥ 0.6 for 44% and 29% of sites for LUE and P-model respectively). The LUE model performs better than P-model as we optimize parameters in temperature, vapor-pressure deficit functions and consider the cloudiness effects. Further investigation of the role of soil moisture stress reveals that it substantially improves the P-model’s (which already considers acclimation of parameters) performance (from an NSE of -0.94 to 0.93) in simulating annual average GPP per site-year. For both models, optimized parameter values vary more across the sites than in the site-years. Moreover, we analyze the role of data versus model epistemic uncertainty in estimating the IAV of GPP. Our model-data-integration experiments reveal current models’ limitations in capturing the IAV of carbon flux and guide their improvements.

 

47 Evaluation of atmospheric CO2 transport across scales from cities to continents

Poster

Anna Agustí-Panareda1*, Michail Diamantakis1, Ivan Bastak-Duran2, Peter Bechtold2, Nicolas Bousserez2, Luca Cantarello2, Frédéric Chevallier3, Andreas Christen4, Richard Engelen2, Vincent de Feiter5, Chiel van Heerwaarden5, Leena Järvi6, Maarten Krol5, Ernest Koffi2, Thomas Lauvaux7, Sarah-Jane Lock1, Sylvie Malardel8, Wouter Peters5, Michel Ramonet3, Bart van Stratum5, Giovanni Tuomolo1, Stefan Versick9, Jordi Vilà Guerau de Arellano5

1ECMWF, Reading, United Kingdom. 2ECMWF, Bonn, Germany. 3LSCE-IPSL, Gif-sur-Yvette, France. 4University of Freiburg, Freiburg, Germany. 5Wageningen University, Wageningen, Netherlands. 6Helsinki University, Helsinki, Finland. 7University of Reims Champagne-Ardenne, Reims, France. 8Meteo France, Toulouse, France. 9Karlsruhe Institute of Technology, Karlsruhe, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

To support the development of the new European anthropogenic CO2 emissions Monitoring and Verification Support capacity (CO2MVS) within the Copernicus programme of the European Commission, the EU-funded Carbon Atmospheric Tracer Research to Improve Numerical schemes and Evaluation (CATRINE) project aims to evaluate and improve the numerical schemes for tracer transport in CO2MVS and more widely in the Copernicus Atmosphere Monitoring Service (CAMS). This will be done by using very high-resolution models at sub-kilometre resolutions to assess and improve the transport processes at city scales relevant to the ICOS Cities project and global models (at resolutions of 100 km or smaller) that provide information of the large-scale transport relevant for the global carbon budget and boundary conditions to the local very high-resolution limited-area models. The project will define protocols and metrics for evaluating tracer transport models at both global and local scales and provide links between the two scales by sharing boundary conditions and city-scale observations to evaluate the capability of both local and global systems to simulate atmospheric CO2 signals from anthropogenic emissions. Test beds based on field campaign case studies will be developed, along with suitable metrics for tracer transport evaluation with a range of tracers and observations from field campaigns and operational networks like ICOS. These metrics will be employed in the operational CO2MVS to evaluate the implementation of new transport model developments, characterise transport accuracy and representativity in data assimilation, and provide a quality control stamp of tracer transport accuracy. 

 

48 Higher global gross primary productivity under future climate with more advanced representations of photosynthesis

Oral

Matthias Cuntz1*, Jürgen Knauer2,3, Benjamin Smith2, Josep P Canadell3, Belinda E Medlyn2, Allison C Bennett4, Silvia Caldararu5,6, Vanessa Haverd3

1Université de Lorraine, AgroParisTech, INRAE, UMR Silva, Nancy, France. 2Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia. 3CSIRO Environment, Canberra, ACT, Australia. 4School of Ecosystem and Forest Science, University of Melbourne, Richmond, VIC, Australia. 5Botany, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland. 6iCRAG SFI Research Centre in Applied Geosciences, Dublin, Ireland

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Gross primary productivity (GPP) is the key determinant of land carbon uptake, but its representation in terrestrial biosphere models (TBMs) does not reflect our latest physiological understanding. We implemented three empirically well supported but often omitted mechanisms into the TBM CABLE-POP: photosynthetic temperature acclimation, explicit mesophyll conductance, and photosynthetic optimization through redistribution of leaf nitrogen. We used the RCP8.5 climate scenario to conduct factorial model simulations characterizing the individual and combined effects of the three mechanisms on projections of GPP. Simulated global GPP increased more strongly (up to 20% by 2070-2099) in more comprehensive representations of photosynthesis compared to the model lacking the three mechanisms. The experiments revealed non-additive interactions among the mechanisms as combined effects were stronger than the sum of the individual effects. The modeled responses are explained by changes in the photosynthetic sensitivity to temperature and CO2 caused by the added mechanisms. Our results suggest that current TBMs underestimate GPP responses to future CO2 and climate conditions.

 

49 The AmeriFlux Management Project: Overview and the Year of Remote Sensing

Poster

Sebastien Biraud1*, You-Wei Cheah1, Trevor keenan1,2, Margaret Torn1,2

1Lawrence Berkeley Lab, Berkeley, USA. 2University California, Berkeley, Berkeley, USA

Session 17. Best Practices in the landscape of Research Infrastructures: Cooperation, Co-location and other lessons learned

AmeriFlux is a network of sites and scientists measuring ecosystem carbon, water, and energy fluxes across the Americas using eddy covariance techniques—and the many scientists who use these data.  The US Department of Energy funded AmeriFlux Management Project (AMP, ameriflux.lbl.gov) aims to enhance the value of AmeriFlux for Earth system modeling, terrestrial ecosystem ecology, remote sensing, and many other fields. AMP has teams focused on four tasks: Technical support and QA/QC, Data support and QA/QC, Core site support, and Outreach. The network continues to grow. In April 2024, AmeriFlux registered its 660th site. We make 3,426 site-years of flux/met data, from 491 sites, publicly accessible. These data are used by a large community of scientists and practitioners around the world. To maintain a high level of service, AMP invests in new data capabilities and is pioneering a new mode of evaluating each site’s data quality (e.g., remote data “visits” and mini workshops). We also benefit from productive partnerships. For example, the National Science Foundation (NSF) funded NEON’s 47 AmeriFlux sites make it the single largest network-within-the-network. We co-develop data standards and products with the ICOS ETC. We work closely with the NSF-funded FLUXNET-Coop, which co-sponsors workshops, builds early career resources, and strengthens international connections among flux networks. This poster will highlight some of these recent activities; ongoing initiatives for remote sensing and for urban fluxes; and special offerings for scientists, such as the Rapid Response Systems (loaner eddy flux systems for urban environments and other research opportunities).

 

51 Advancing Greenhouse Gas Isotopic Measurements: Evaluating the Compatibility and Efficiency of Picarro Gas Autosampler with Picarro Isotopic Analyzers

Oral

Keren Drori*, Joyeeta Bhattacharya, Magdalena Hofmann, Jan Woźniak, Jinshu Yan, Tina Hemenway.

All authors: Picarro, Santa Clara, USA.

Session 18. Manufacturers' Session

The greenhouse gas research community faces a growing demand for automated solutions tailored to isotopic measurements of greenhouse gases (e.g., isotopic CO2/CH4). Traditional solutions often entail significant initial and maintenance costs, intricate deployment and maintenance processes, and limited fieldwork adaptability. Anticipating this challenge, the Picarro Gas Autosampler is poised to attract growing interest for its anticipated compatibility with Picarro isotopic Carbon analyzers featuring low flow rates (<50 scc/m), promising efficient isotopic measurements. This report delves into the compatibility, efficiency, and advantages of the Picarro Gas Autosampler when paired with the Picarro G2201-i analyzer. Our experiments showcase remarkable precision and accuracy in isotopic measurements of greenhouse gases. Additionally, we explore factors such as linearity in dilution factors and characterize memory effects and variability across different gas species (e.g., comparing CO2 vs CH4). Moreover, the report offers practical recommendations on methods and best practices for conducting isotopic measurements of greenhouse gases. In summary, the Picarro Gas Autosampler, when combined with the Picarro G2201-i analyzer, emerges as a compelling, cost-effective, and user-friendly solution for isotopic measurements of greenhouse gases, offering a distinct advantage over traditional alternatives.

 

52 Unlocking Insights: Evaluating Simulated CO2 Over Europe Through Aircraft Observations and Error Apportionment

Oral

Ðanilo Custódio1*, Mats Militzer1, Saqr Munassar1, David Ho1, Frank-Thomas Koch2, Christian Rödenbeck1, Christoph Gerbig1

1Max-Planck-Institut für Biogeochemie, Jena, Germany. 2Deutscher Wetterdienst, Hohenpeissenberg, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Inverse modeling is pivotal in inferring surface-atmosphere exchange of CO2 based on atmospheric observations of CO2 concentration. However, uncertainties in inversion estimation, including emission accuracy, spatial-temporal resolution, and reliability of the transport scheme are challenges which should be addressed. Quality assessment and uncertainty decomposition are crucial tasks in greenhouse gases modeling, requiring verification and comparison studies with independent observations, which ultimately anchor the reality. 

The main objective of this study is to benchmark and characterize uncertainties within the retrieval chain of COestimated by the CarboScopo Regional inversion (CSR) and CAMS, employing aircraft observations from both commercial flights and dedicated research aircraft. Moreover, the research focuses on decomposing the mismatch between observed and modeled CO2 concentrations into distinct error vectors, aiming to apportion the strength of uncertainties associated with each vector. The outcomes of this study strongly indicate that there is a compelling need for enhancements in the parameterization of dynamics to elevate the performance of the CSR model. The observed results underscore the influence of these specific model components on the accuracy and reliability of CO2 estimates within the regional domain. Our study shed light on the uncertainty of CO2 estimated over Europe and reveals significant findings.We observed systematic underestimations in CO2 concentrations within the planetary boundary layer height, indicating deficiencies in the model&apos;s representation, particularly in fossil fuel emissions and boundary layer dynamics. Specifically, our analysis highlights that dynamics account for over 60% of the CO2 mismatch in the CSR model, with emissions contributing 28% to this discrepancy.

 

53 Biodiesel, Chlorella and Decarbonization industry

Poster

Dr. Kakha NADIRADZE*, Nana PHIROSMANASHVILI, Tekla NADIRADZE

Association for Farmers Rights Defense, AFRD, Tbilisi, Georgia

Session 18. Manufacturers&apos; Session

Due to the declining fossil fuel resources as well as the need for an alternative source of biodegradable source of energy, biodiesel has a great advantage over conventional fuel due to its low content of particulates. This study investigated the production and characterization of biofuels produced from the fresh water microalgae; Chlorella vulgaris. The goal of our project is to create a technology at the national level within the framework of the My Climate project, which involves increasing the volume of biomass produced by microalgae, which will contribute to the adoption of biofuel (biodiesel) as an alternative energy source and its commercial development. Within the framework of our project, microalgae (chlorella) is considered as a raw material for biofuel. For the maximum efficiency of such fuels, a high growth rate of plant biomass is required. Chlorella is an ideal raw material in this regard, that is, an active producer of biomass - with a high percentage of proteins, fats, carbohydrates, vitamins... In total, more than 650 substances are concentrated in it, the content of which is much higher than the content of meat, milk, vegetables and fruits. Materials and Methods: Water was sampled from Sharada industrial run-off within Kano metropolis for isolation and identification of algal species. Microalgae have the potential to become the primary source of biodiesel, catering to a wide range of essential applications such as transportation. This would allow for a significant reduction in dependence on conventional petroleum diesel.

 

54 Optimizing spatial resolution in landcover classification for accurate methane emissions estimates in Arctic and Boreal regions.

Poster

Joshua Hashemi1*, Aleksi Räsänen2,3, Tarmo Virtanen4, Sari Juutinen5, Annett Bartsch6, Laura Chasmer7, Guido Grosse1, McKenzie Kuhn8, Mark Lara9, Miska Luoto4, Pekka Niittynen4, David Olefeldt10, Anna Virkkala11, Carolina Voigt12,13, Claire Treat1

1Alfred-Wegener Institute, Potsdam, Germany. 2Natural Resources Institute Finland (LUKE), Oulu, Finland. 3University of Oulu, Oulu, Finland. 4University of Helsinki, Helsinki, Finland. 5Finnish Meteorological Institute, Helsinki, Finland. 6b.geos GmbH, Korneuburg, Austria. 7University of Lethbridge, Lethbridge, Canada. 8University of British Columbia, Vancouver, Canada. 9University of Illinois, Urbana, USA. 10University of Alberta, Edmonton, Canada. 11Woodwell Climate Research Centre, Falmouth, USA. 12Universität Hamburg, Hamburg, Germany. 13University of Eastern Finland, Kuopio, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Quantifying methane emissions from Arctic and Boreal wetlands is critical for constraining uncertainty in the global methane budget. However, current estimates exhibit considerable variability, in part, due to challenges in accurately mapping wetland distribution and type. Here, we investigate the influence of the spatial resolution of landcover classification maps on regional methane flux estimates at several locations across the Arctic and Boreal. Utilizing high-resolution landcover classification maps (<2.5 m) and chamber-based methane flux measurements, we estimate regional methane emissions at various spatial resolutions to show how emission estimates vary as a function of landcover classification pixel size. Our results show regional estimates are most accurate at spatial resolutions of ≤25 m, with coarser resolutions yielding significantly less reliable estimates. Fragmented wetlands, in particular, may be misrepresented, leading to the underestimation or misallocation of methane relevant landcover classes. Additionally, we highlight the significance of wetland type, showing that fens are more sensitive to misrepresentation due to coarse resolution than bogs or wetlands in general. Current wetland mapping products often overlook smaller wetlands, leading to inaccuracies. Findings emphasize the need to use landcover classification maps with the appropriate thematic and spatial resolution to accurately represent those landcover types that are important for methane dynamics. These insights have implications for reconciling top-down and bottom-up approaches and deepening our understanding of methane dynamics in the context of a changing climate.

 

55 Greenhouse Gas Data assimilation using ICOS observation data for the ITMS project

Poster

Niels Heinrich Keil*, Valentin Bruch, Roland Potthast, Andrea Kaiser-Weiss

Deutscher Wetterdienst, Offenbach, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

For the purpose of observation based CH4 emission verification, we develop a data assimilation system for the project Integrated greenhouse gas monitoring system for Germany (ITMS).
   Employing the numerical weather model ICON and its aerosol and trace gas (ART) extension, three-dimensional CH4 model fields are constructed from given prior CH4 emissions over Europe and CH4 initial and boundary concentration provided by Copernicus.
   To pull the modelled fields closer to reality, 3D-Var and ensemble based EnVar data assimilation methods are used to combine modelled CH4 fields with ICOS station observations resulting in a CH4 analysis.
   The added value of the CH4 analysis can be shown by comparing statistical errors of the modelled fields and of the analysis on observation stations independent of the data assimilation or in different measurement heights.
   The implementation is efficient and is based upon systems of the DWD operational data assimilation.

 

56 Long-term CO2 flux measurements from an intensively managed temperate grassland

Poster

Yi Wang*, Iris Feigenwinter, Lukas Hörtnagl, Nina Buchmann

Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Grassland ecosystems cover about 40% of the global land area (excluding Greenland and Antarctica) and serve a unique role in the global carbon (C) cycle. The net CO2 uptake in managed grasslands is substantially influenced by climate conditions, accompanied by interactions with land management practices. With the eddy covariance (EC) technique, the net ecosystem exchange (NEE) of CO2 can be directly measured. NEE represents the balance between two different ecosystem processes: gross primary production (GPP; amount of CO2 assimilation through photosynthesis), and ecosystem respiration (Reco; amount of CO2 released via plant and soil respiration).

This study aims to assess the dynamics of CO2 fluxes at Chamau (CH-CHA as part of Swiss FluxNet), an intensively managed temperate grassland in Switzerland. Using machine learning approaches for 19 years (2005-2023) of EC flux, meteorological, and management data, our objectives are (1) to identify key drivers of GPP and Reco at different time scales (i.e., daily, seasonal, annual), (2) to investigate changes in grassland regrowth after management events (i.e., mowing, grazing, fertilization, sward renewal), and (3) to examine the ecophysiological responses (e.g., water use efficiency) to both climate change and management practices. Our results can provide further insights to help optimize grassland management practices to increase sward productivity and develop mitigation strategies for current and future climate risks.  

 

57 Flux ratios of CO2, CO, and NOx: an inter-city comparison between Paris and Zurich using urban tall-tower eddy covariance

Oral

Rainer Hilland1*, Stavros Stagakis2, Pascal Rubli3, Lukas Emmenegger3, Laura Bignotti4, Benjamin Loubet4, Samuel Hammer5, Andreas Christen1

1University of Freiburg, Freiburg, Germany. 2University of Basel, Basel, Switzerland. 3EMPA, Dübendorf, Switzerland. 4INRAe, Palaiseau, France. 5University of Heidelberg, Heidelberg, Germany

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

In-situ measurements of urban greenhouse gas (GHG) emissions play a critical role in quantifying cities’ contributions to regional and global emissions and are a key tool in the validation of city emission inventories and models. Cities are also complex environments containing a multitude of anthropogenic emission sources such as traffic, residential heating, and industrial production. Correct sectoral attribution of urban GHG emissions is necessary to monitor emission reduction efforts, compare against emission inventories, and separate anthropogenic from biogenic emissions.

As part of the ICOS-Cities (PAUL - Pilot Application in Urban Landscapes) project, tall-tower urban eddy covariance (EC) systems were installed in both Paris, France and Zurich, Switzerland. Use of a high-frequency multi-species gas analyser (MGA7, MIRO Analytical, Switzerland) enabled simultaneous measurements of CO2, CO, CH4, NOx, N2O, and H2O fluxes. EC measurements provide gas fluxes which integrate all emission sources and sinks within the measurement footprint. By examining the ratio of these gas fluxes in combination with a spatially-resolved emission inventory within the EC footprint, one may validate or improve the emission inventory.

We present eight months of EC flux ratios from Zurich (August 2022 until March 2023) and six months of EC flux ratios from Paris (January 2024 to June 2024). We investigate what we can learn from the differences in flux ratios between the two cities, as well as discuss the challenges and potential of using multi-species EC measurements to separate urban GHG emission sources.

 

58 Refining the Global Picture: the Impact of Increased Resolution on CO₂ Atmospheric Inversions using OCO-2 XCO₂ retrievals

Poster

Zoé Lloret*, Frédéric Chevallier, Anne Cozic

LSCE/CEA, Gif-sur-Yvette, France

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The threat posed by the increasing concentration of carbon dioxide (CO₂) in the atmosphere motivates a detailed and precise estimation of CO₂ emissions and absorptions over the globe. This study refines the spatial resolution of the CAMS/LSCE inversion system, achieving a global resolution of 0.7° latitude and 1.4° longitude, or three times as many grid boxes as the current operational setup. In a two-year inversion assimilating the midday clear-sky retrievals of the column-average dry-air mole fraction of carbon dioxide (XCO₂) from NASA’s second Orbiting Carbon Observatory (OCO-2), the elevated resolution demonstrates an improvement in the representation of atmospheric CO₂, particularly at the synoptic time scale, as validated against independent surface measurements. Vertical profiles of the CO₂ concentration differ slightly above 22 km between resolutions compared to AirCore profiles, and highlight differences in the vertical distribution of CO₂ between resolutions. However, this disparity is not evident for XCO₂, as evaluated against independent reference ground-based observations. Global and regional estimates of natural fluxes for 2015-2016 are similar between the two resolutions, but with North America exhibiting a higher natural sink at high-resolution for 2016. Overall, both inversions seem to yield reasonable estimates of global and regional natural carbon fluxes. The increase in calculation time is less than the increase in the number of operations and in the volume of input data, revealing greater efficiency of the code executed on a Graphics Processing Unit. This allows us to make this higher resolution the new standard for the CAMS/LSCE system.

 

59 Towards regional CH4 inversions with ICON-ART assimilating satellite TROPOMI data over Europe

Poster

David Ho1*, Michael Steiner2, Erik Koene2, Michał Gałkowski1,3, Friedemann Reum4, Julia Marshall4, Christoph Gerbig1

1Max-Planck-Institut für Biogeochemie, Jena, Germany. 2Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland. 3AGH University of Science and Technology, Kraków, Poland. 4Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Inverse modeling is a top-down technique which utilizes atmospheric observations to infer greenhouse gas (GHG) emissions. With this application in mind, satellite retrievals of GHGs are an attractive data source due to their dense spatial coverage compared to typically sparse surface networks. This study aims to assimilate satellite data at high resolution to independently locate and quantify GHG sources and sinks, aiding carbon budget studies and policymakers. The work also serves to develop the groundwork for the development of Germany&apos;s Integrated GHG Monitoring System (ITMS).
   
   We couple the numerical weather prediction and atmospheric transport model ICON-ART with an Ensemble Kalman Filter (EnKF) based inversion system, using the CarbonTracker Data Assimilation Shell (CTDAS). Targeting total CH4 fluxes over Europe, we use ccolumn-integrated methane measurements (XCH4) from the TROPOspheric Monitoring Instrument (TROPOMI). Prior anthropogenic emissions are taken from the CAMS-GLOB-ANT_v4.2 inventory, while natural sources are included as well from CAMS-GLOB-BIO_v3.1.
   
   A synthetic study conducted for June 2018, demonstrates the system&apos;s ability to capture prescribed spatial patterns in emission fields, using pseudo-observations from satellite retrievals with realistic coverage. CH4 fluxes were retrieved at 0.25° x 0.25° resolution, and prior emissions were scaled to optimally fit the measured values. Real observations are then assimilated, providing emission estimates and their associated uncertainties.
   
   This study showcases the potential of satellite retrievals in inverse modeling, enabling us to extend its application to other GHG species, and serving as preparation for the Copernicus Anthropogenic Carbon Dioxide Monitoring (CO2M) mission.

 

60 Addressing PhenoCam supply chain limitations with low cost (DIY) drop-in replacements

Poster

Koen Hufkens*

BlueGreen Labs (BV), Melsele, Belgium

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

PhenoCams provide a critical vegetation monitoring services, providing information on the state of the vegetation throughout the seasons with conventional (RGB and infrared) images. However, the deployment of PhenoCams has recently been limited due to post-COVID supply chain issues and a shortage of the recommended StarDot SC5 model (used in the EU/US PhenoCam networks). These supply chain issues have highlighted a weakness in our hyper-connected economies and the over-reliance on hardware availability and just-in-time value chains, which might not be sustainable from a practical and environmental perspective.
   
   Here, I present two solutions to PhenoCam related hardware supply chain issue. First, I introduce the successor of the StarDot SC5 camera, the StarDot Live2 camera and the automated setup through the Phenocam Installation Tool (PIT v2). This setup will supersede the old StarDot SC5, which is no longer available from the vendor. 

https://github.com/bluegreen-labs/phenocam_installation_tool_v2

Second, I provide an open hardware drop-in replacement for default PhenoCam solutions based around system on a chip (SoC) hardware. Our setup serves as low cost and highly redundant solutions in case of budgetary or hardware availability constraints, which can be repurposed for scientific outreach and educational projects. These open hardware solutions are built around 3D printed housings (support structures) and off-the-shelve components, allowing for the use of various vendors, or hardware configurations.

https://bluegreenlabs.org/post/bluegreen-labs-phenocam/

 

61 Potential for coupling TIR/SWIR satellite sounders for wildfire research: CO from 2020-2023 megafires.

Poster

Leonid Yurganov*

UMBC, Baltimore, USA

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

TIR sounders (MOPITT, AIRS, IASI, etc.) detect outgoing thermal radiation from the Earth, while SWIR instruments (GOSAT, TROPOMI, etc.) use solar radiation reflected and/or scattered from the surface or clouds. Both types provide the total column number of molecules (in molec/cm2) or VMR averaged over the entire depth of the atmosphere (in our case Xco). A fundamental limitation of TIR data is the low sensitivity to PBL. SWIR probes have the same height sensitivity in clear sky conditions. Combining these data on a daily basis opens up opportunities for studying gas concentrations in the lower troposphere. This report provides an analysis of the evolution of CO in the middle and lower troposphere from the onset of forest fires to the process of CO dissipation after the end of the fire.

Megafires occurred in Australia in the summer of 2019/2020, in Siberia in 2021 and in Canada in 2023. According to the global database GFED4c,  all of these events produced record emissions of CO, CO2 and CH4,. The Xco differential measured by the TROPOMI and AIRS instruments clearly indicates the accumulation of pyro-CO in the lower troposphere and the rise of polluted air upward over time. The dispersion process occurs in both the lower and middle troposphere, but long-range transport predominates in the middle troposphere, where AIRS sensitivity is quite high. This technique could potentially be greatly improved by including specific averaging kernels for the TIR and SWIR cases, as well as a priori.

 

62 Identifying hotspots of greenhouse gas emission from drained peatlands in the European Union

Oral

Quint van Giersbergen1*, Alexandra Barthelmes2, John Couwenberg2, Christian Fritz1, Kristiina Lång3, Franziska Tanneberger2

1Radboud University, Nijmegen, Netherlands. 2Greifswald University, Greifswald, Germany. 3Natural Resources Institute Finland, Helsinki, Finland

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Greenhouse gas emissions (GHG) emissions from drained peatlands in Europe contribute substantially (almost 8%) to the total EU anthropogenic GHG emissions. Current European-scale monitoring of these emissions lacks high-resolution spatial data, and individual countries differ with respect to data quality (e.g., lacking wall-to-wall reporting) which hinder integrated and effective mitigation policy implementation.

Part of the PRINCESS project, we present the first detailed land use distribution map for EU peatlands (plus several Non-EU countries), the first map on GHG emissions and a map on GHG emission hotspots. In our analysis we combined peatland distribution land use and drainage maps. Our results show that undrained peatlands and Forest Lands are wide-spread at high latitude whereas Grasslands and Croplands are most prominent around latitude 50°-55°. We identified three main hotspots in the North Sea region: northeastern Ireland, western Netherlands, and northwestern Germany, collectively responsible for 20% of drainage and land use related emissions from European peatlands, over just 8% of the total peatland area. 

The study emphasizes, that mitigating emissions from European drained peatlands is crucial for achieving climate goals. It reveals substantial underestimation of emissions in current National Inventory submissions (NIS) to the UNFCCC, amounting to 120-146 Mt CO2-e annually on the EU+ scale, demanding a reassessment of policy measures. Policy instruments implementing and monitoring measures to reach EU’s zero emission within LULUCF sector need to be peatland specific and peatland emission reporting methodology should be regularly validated.

 

64 Atmospheric variability of carbon dioxide and methane at the Lamezia Terme (Southern Italy) WMO/GAW regional station

Poster

Luana Malacaria1*, Teresa Lo Feudo1, Elenio Avolio1, Ivano Ammoscato1, Daniel Gullì1, Salvatore Sinopoli1, Mariafrancesca De Pino1, Francesco D&apos;Amico1, Giorgia De Benedetto1, Claudia Roberta Calidonna1, Paolo Cristofanelli2, Domenico Parise1

1National Research Council of Italy – Institute of Atmospheric Sciences and Climate, Area Industriale Comp. 15, 88046, Lamezia Terme (CZ), Italy. 2National Research Council of Italy – Institute of Atmospheric Sciences and Climate, Via P. Gobetti 101, 40129, Bologna (BO),, Italy

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

With increasing concern over climate change and its environmental impacts, effective greenhouse gases (GHGs) control strategies are of pivotal importance. The use of models (i.e., STILT Stochastic Time Inverted Lagrangian Transport), statistical techniques, and experimental data analysis provide valuable tools for quantifying emissions and identifying trends of GHGs. The Mediterranean basin is considered a global hotspot for air-quality and climate change. Since 2015, the World Meteorological Organization/Global Atmosphere Watch (WMO/GAW) permanent observatory of Lamezia Terme (LMT) in Calabria, Southern Italy, has been continuously measuring GHGs in the atmosphere. The measurements were conducted by a Picarro G2401 analyzer. Specific calibration routines were carried out using the primary standards of calibration from National Oceanic and Atmospheric Administration – Global Monitoring Laboratory (NOAA – GML), as well as secondary standards were used to evaluate possible drifts, and the stability of calibration factors. This coastal monitoring station, located 600 m from the Tyrrhenian Sea shore, allows to study atmospheric carbon dioxide (CO2) ppm and methane (CH4) ppb concentrations at the local and continental scales, in a region with peculiar Mediterranean climatic features. This work presents a preliminary characterization of CO2 and CH4 variability in the central Mediterranean basin. We show the hourly concentration data of GHGs over a 9-years period, from 2015 to 2023, that represent a relevant long-term dataset of these gases over Southern Italy. This work would be a gainful contribution towards a more accurate knowledge of greenhouse gases trends in the atmosphere in the central Mediterranean region.

 

65 Forest ecosystem transpiration and carbon sequestration at the footprint level of an ICOS site

Oral

Holger Lange*, Junbin Zhao, Morgane Merlin, Ryan Bright

NIBIO, Ås, Norway

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Transpiration is an important water flux in forests closely tied with carbon dioxide (CO2) sequestration through stomatal control at the tree level. While it is a key process underlying water and carbon fluxes, it remains challenging to measure transpiration at larger spatial scales. In the footprint of the ICOS class 2 tower at Hurdal in Norway (NO-Hur), we installed sap flow probes (Heat Field Deformation and Heat Ratio Method) on 13 Norway spruce trees, and automatic point or band dendrometers on 25 trees, measuring time series of transpiration and stem diameter fluctuations at 10 minutes resolution. We analyze the relationship between stem diameter changes and sap flow, and the dependence of this relationship on physical attributes of individual trees (height, diameter at breast height, age, sapwood length), meteorology and soil climate. Phase Synchronization Analysis reveals that there is a delayed response of diameter change to sap flow, and we thus construct a time-lagged empirical model representing flow patterns across diurnal and seasonal cycles. This model allows for predicting tree-level transpiration also for trees not equipped with sap flow devices. Using the ICOS forest inventory and Lidar data, we develop a dynamic model for the total transpiration within the footprint (average area 0.63 km2) at high temporal resolution. Combining the tree level measurements with ecosystem level eddy covariance data, we also explore the coupling of carbon and water fluxes and how sap flow and dendrometer data contribute to explain ecosystem CO2 sequestration.

 

66 The Integrated Greenhouse gas Monitoring System (ITMS) for Germany: an update on recent progress

Poster

Christoph Gerbig1*, Andrea Kaiser-Weiss2, Heinrich Bovensmann3, Ralf Kiese4, Clemens Scheer4, Rachael Akinyede1, Beatrice Ellerhoff2, Maximilian Reuter3, Hannes Imhof4, Christian Plaß-Dülmer5, Andreas Fix6

1Max Planck Institute for Biogeochemistry, Jena, Germany. 2Germany’s National Meteorological Service (DWD), Offenbach am Main, Germany. 3University of Bremen, Institute of Environmental Physics (IUP), Bremen, Germany. 4Karlsruhe Institute of Technology , Institute for Meteorology and Climate Research (IMK-IFU), Garmisch-Partenkirchen, Germany. 5Hohenpeissenberg Meteorological Observatory, Deutscher Wetterdienst (DWD), Hohenpeissenberg, Germany. 6Institute of Atmospheric Physics, German Aerospace Center (DLR), Oberpfaffenhofen, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The Integrated Greenhouse Gas Monitoring System for Germany (ITMS) is a national initiative to establish an operational service for the provision of independent estimates of GHG fluxes for Germany. The main aim is to enhance transparency in reporting of emissions and natural fluxes, specifically with regards to emission reduction on the path to net zero. ITMS is a highly interdisciplinary project, bringing together diverse scientific communities involved in atmospheric observations, satellite observations, biosphere and agriculture research, inventory experts, and atmospheric transport and inverse modelling. ITMS utilizes observational datastreams from research infrastructures such as ICOS and IAGOS to constrain Germany’s GHG fluxes into the atmosphere using inverse atmospheric transport modelling. ITMS also develops tailored remote sensing products e.g. from current and upcoming satellite missions. Detailed a priori emissions are generated consistent with UNFCCC reported emissions, while priors for natural fluxes are based on various process based as well as diagnostic models. Inverse modelling is deployed at mesoscale resolution, using the CarboScope-Regional (CSR) inversion system operated at the MPI- BGC as a back-bone and reference system, while developing ICON-ART based data assimilation for future operational services at the DWD. The presentation will give an overview of current status, and will indicate some research highlights achieved so far.

 

67 European Obspack: compilation of all CO2, CH4 and N2O measurements in Europe

Poster

Clément Narbaud1*, Michel Ramonet1, Lynn Hazan1, Alex Vermeulen2, Oleg Mirzov2, Amara Abbaris1, Ute Karstens2, Léonard Rivier1

1LSCE, Gif-sur-Yvette, France. 2ICOS Carbon Portal, Lund, Sweden

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The dense network of greenhouse gas observations enables us to characterize trends and seasonal anomalies on a regional scale. The ObspackEU dataset was initiated in 2022, covering at that time CO2 and CH4 observations. After its first update in September 2023, the dataset represented in total more than 1170 years of CO2 data and more than 1026 years of CH4 data, distributed among 65 stations, 38 of which are ICOS-labelled. Thus, ICOS-labelled data represent about 36.5% of the total dataset, with a proportion increasing up to 72.6% when considering only 2022 data. For the year 2024, a new update scheduled for July, will aggregate data up to the end of March 2024 enriched for the first time with N2O time series. 28 stations are foreseen to provide data which should represent around 450 years of measurements in Europe. We will present updated growth rates for the three main greenhouse gases, as well as the striking seasonal anomalies observed in Europe in recent years. We will present how these seasonal anomalies observed at stations can be propagated using back-trajectories calculated at the ICOS carbon portal, in order to obtain a regional picture of concentration anomalies.

 

68 Influence of nutrient availability on water-use efficiency of European semi-natural ecosystems

Poster

Ladislav Šigut1*, Filip Oulehle1,2

1Global Change Research Institute of the Czech Academy of Sciences, Brno, Czech Republic. 2Czech Geological Survey, Prague, Czech Republic

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

The ecosystem CO2 and H2O fluxes are typically studied in the context of changing micrometeorological conditions, such as light, water availability, and temperature. However, CO2 and H2O budgets are further modulated by nutrient availability (NA) and air deposition (AD). The influence of changes in NA and AD is observable only over longer periods, thus when evaluating the time series of eddy covariance fluxes it is more practical to compare across different sites with contrasting levels of NA and AD. Water-use efficiency (WUE) is a useful indicator of ecosystem performance and fitness, and it allows us to evaluate changes in ecosystem functioning since it reflects the degree of stomatal regulation of carbon assimilation and water loss.

In this contribution, we will assess the effect of NA of nitrogen, phosphorus, and calcium ions on WUE. For this purpose, we take advantage of the existing leaf NA survey performed yearly on the sun-exposed part of the vegetation canopy within ICOS ecosystem stations. Though nutrient content in the soil is not available, leaf samples are expected to be a better measure as they should reflect both soil NA and nutrient accessibility to the plant. The wide selection of semi-natural ecosystems across Europe will allow us to evaluate the capability of the ICOS network to capture the impact of NA on WUE. Furthermore, we will evaluate how leaf NA relates to AD, especially in the case of nitrogen depositions. For this purpose, EMEP MSC-W modeled air deposition results will be used.

 

69 Climate-induced changes in carbon flux dynamics of an alpine grassland: insights from transplantation experiment

Oral

Federica D’Alò1*, Olga Gavrichkova1, Angela Augusti1, Luigimaria Borruso2, Leonardo Latilla3, Michele Mattioni1, Maurizio Sarti1, Leonardo Montagnani2

1Research Institute on Terrestrial Ecosystems, National Research Council, Porano, Italy. 2Free University of Bozen, Bozen, Italy. 3Research Institute on Terrestrial Ecosystems, National Research Council, Montelibretti, Italy

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Alpine regions undergo faster warming rates than the global average as a result of climate change (CC). This makes them highly vulnerable to functional collapse. Alpine grasslands store significant amounts of carbon in the soil, but the impact of CC on their carbon storage and sequestration capacities is still uncertain. To assess the CC effects on CO2 fluxes in alpine grasslands, soil monoliths were transplanted from 2500m to 1500m altitude in Val Veny, Courmayeur, Italy, simulating a 5°C temperature increase as projected for 2100 by the IPCC’s RCP8.5 scenario. Two transplantations were conducted: in 2022 (old plots) and in 2023 (new plots), allowing the study of carbon fluxes in different acclimation stages. Continuous chamber systems were installed to measure CO2 efflux in transparent and opaque chambers with 15min time step in undisturbed control and transplanted in different years plots. During the measurement campaign, in August 2023, a 5-day heatwave occurred at both altitudes, providing insight into the extreme event impact. Our findings showed undisturbed plots acting as minor carbon sinks throughout the study period, while all transplanted monoliths acting as carbon sources, especially the new ones. Notably, increased temperature and dryness disrupted transplanted systems functioning, leading to a significant post-heatwave decline in carbon uptake. New plots experienced decreased leaf area and species composition changes due to selective mortality, additionally affecting carbon exchange. Our data highlight the important impact of CC, particularly heatwaves, on alpine grassland carbon balance, indicating that one year of acclimation is insufficient for sequestration function recovery.

 

70 Comparison of gross primary productivity derived from satellite-based models with field-measured products: case studies of tropical peat swamp forests in Borneo, Southeast Asia.

Poster

Yohanes R.S. Ginting1*, Leonie Esters1, Gerbrand Koren2, Bibi S. Naz3, Agung B.S. Noor4

1Climate Monitoring Group, Department of Meteorology, Institute of Geosciences, University of Bonn, Bonn, Germany. 2Copernicus Institute of Sustainable Development, Utrecht University, Utrecht, Netherlands. 3Institute of Bio- and Geosciences: Agrosphere (IBG-3), Research Centre Jülich, Jülich, Germany. 4Department of Meteorology, Faculty of Mathematics and Natural Sciences, IPB University, Bogor, Indonesia

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

The total quantity of carbon fixed by photosynthesis per unit time in an ecosystem is referred to as gross primary productivity (GPP), and it is an important activity in the Earth’s carbon cycle. In near-equilibrium conditions, GPP is calculated as the sum of daily net carbon exchange and ecosystem respiration (GPP = NEE  − Re). In our study, we compared the GPP from satellite-based model estimates with the actual GPP calculated by the eddy covariance method available from the FLUXNET database. We found that the GPP models were able to capture the actual 8-day fluctuations of GPP in tropical peat swamp forests in Borneo (R2 = 0.29–0.33) and model performances showed good estimates (RMSE = 0.70–2.02; MAPE = 5.64–15.33%). Cloud cover on MODIS satellite data is also a challenge in measuring remote sensing indices such as the land surface water index, which is very important as a proxy for Wscalar to estimate GPP-based models.

 

71 Influence of open fire emissions to carbon dioxide (CO2) observed at the Mt. Cimone station (Italy, 2165 m asl).

Poster

Paolo Cristofanelli1*, Pamela Trisolino1, Calzolari Francescopiero1, Busetto Maurizio1, Claudia Roberta Calidonna2, Amendola Stefano3, Arduni Jgor4, Cosimo Fratticioli5,6, Rabia Ali Hundal7, Michela Maione4, Francesca Marcucci3, Angela Marinoni1, Laura Renzi1, Fabrizio Roccato1, Paolo Bonasoni1, Davide Putero8

1CNR, Bologna, Italy. 2CNR, Lamezia Terme, Italy. 3Aeronautica Militare, Sestola, Italy. 4Università di Urbino Carlo Bo, Urbino, Italy. 5Università di Firenze, Firenze, Italy. 6National Institute of Nuclear Physics, Firenze, Italy. 7Scuola Superiore Unversitaria, Pavia, Italy. 8CNR, Torino, Italy

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

This work aimed at investigating on a multi-year framework (2015 – 2021) the contributions of open fire emissions to CO2 observed at the ICOS atmospheric class-2 station Mt. Cimone (CMN, 2165 m a.s.l. - Italy).  A methodology providing indications about the possible presence of wildfire plumes from different European source regions was based on the observed CO, active open fire by MODIS and air mass back-trajectories. An alternative detection method based on the use of a reanalysis dataset (CAMS) was also used.

The results suggested that CMN could be affected by open fire plumes for a fraction of time ranging from 1% to 10% (as a function of the adopted methodology setting). We found a potentially important contributions from Eastern Europe during October - April, while during May - September there was a prevalence from the Mediterranean sectors. 

We detected a notable increase of CO2 residuals with respect to periods not affected by fire perturbations during October - April (from +1.8 to +3.9 ppm, on average). We did not find evident impacts during the summer months, possibly due to a contribution by biospheric uptake during air mass transport to CMN (at least for a fraction of selected events).

We discussed the sensitivity of results as a function of the selection methodology settings, suggesting that the strictest set-up based on the detection of large CO excesses could trace “major” events. A medium level of agreement was found when comparing the our selection methodology with CAMS reanalysis (fraction of PM10 emitted by wildfires). 

 

72 Evaluating the Short-Term Influence of Restoration on Net Ecosystem CO2 Exchange (NEE) in an Irish Peatland

Poster

Md Shamsuzzaman1*, Shane Regan2, Mark O&apos;Connor2, Ultan McCarthy3, Imelda Casey3, Mika Korkiakoski4, Owen Naughton1

1South East Technological University, Carlow, Ireland. 2National Park and Wildlife Service, Dublin, Ireland. 3South East Technological University, Waterford, Ireland. 4Finnish Meteorological Institute, Helsinki, Finland

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

 

Peatlands serve as vital reservoirs for carbon storage, harboring over 50% of the Republic of Ireland&apos;s soil carbon. However, years of mismanagement, including practices like drainage and peat extraction, have transformed these areas into significant carbon emitters. Restoration initiatives are pivotal in Ireland&apos;s commitment to reducing greenhouse gas emissions by 30%, as outlined in the national Climate Action Plan and the Paris Agreement.

Initiated by the National Park and Wildlife Services (NPWS) in 2019, a restoration project commenced at the All Saints raised bog in County Offaly, a designated Special Area of Conservation. Employing an Eddy Covariance tower, we monitored the net ecosystem CO2 exchange (NEE) over a nearly three-year period before and after restoration. Preliminary findings show promising outcomes, notably the establishment of a crucial water reserve supporting the bog&apos;s ecosystem. However, despite ongoing restoration, significant carbon emissions persist.

NEE data illustrates fluctuating trends, with readings rising from 110.89 g C/m² in 2021 to 214.37 g C/m² in 2022, gradually declining as of summer 2023. Further analysis aims to elucidate emission patterns across time and seasons, discerning the key influencers, encompassing both biotic and abiotic factors. This holistic approach provides invaluable insights into restoration efficacy and enhances our comprehension of carbon dynamics within peatland ecosystems. Such insights are indispensable for shaping future conservation strategies and achieving Ireland&apos;s climate objectives.

 

73 Nocturnal fluxes of CO2 and CH4 from Barcelona Metropolitan Area obtained with the Radon Tracer Method

Poster

Roger Curcoll1, Gara Villalba2, Carme Esruch3, Arturo Vargas1, Claudia Grossi1*

1INTE-UPC, Barcelona, Spain. 2ICTA-UAB, Cerdanyola del Vallès, Spain. 3Eurecat, Amposta, Spain

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Urban areas represent the major contributor to the global greenhouse gas (GHG) emissions to the atmosphere. Quantifying their GHG emissions and constraining the associated uncertainties is a scientific challenge and a key factor for fighting the climate change.

Continuous atmospheric measurements of carbon dioxide, methane and of the tracer radon gas have been carried in the INTE-IDAEA station in Barcelona city since January 2022. The GHG measurements, together with ones from three more stations within Barcelona Metropolitan area, are part of the ICOS Cities project. 

Both 222Rn and GHG measurements were analysed and integrated with backtrajectories within the Radon Tracer Method (RTM) to obtain nocturnal fluxes of both CH4 and CO2 for 2022-2023 period. Fluxes estimated using RTM do not differ from those obtained from emission inventories such as EDGAR. Concentrations show a clear annual cycle but fluxes of both CO2 and CH4 remain quite constant along the year, in agreement with inventories.

This study was possible thanks to a collaboration between researchers from the Universitat Politecnica de Catalunya, the Universitat Autonoma de Barcelona and the Consejo Superior de Investigaciones Científicas.

 

74 Using optical and radar inputs data in a machine learning model to predict net ecosystem exchange of cropland

Poster

Sarah Dussot*, Pierre Gutierrez, Gaétan Pique

Netcarbon, Bordeaux, France

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Agriculture is a major contributor to human-induced greenhouse gas emissions. At the same time, agricultural soils have been identified as having great potential to sequester carbon through the introduction of improved management practices, such as cover crops. In order to implement these practices at large scale, a better understanding of the CO2 exchange at the soil-atmosphere interface is required.

Different methods exist to quantify this flux. Direct methods such as flux tower measurements are accurate but limited in spatial coverage. Modelling approaches allow a broader spatial application but they are often crop specific and need to be calibrated for each crop type. Methods using machine learning approaches are emerging and offer important potential for predicting net ecosystem exchange across different crop types.

In this study we present a promising machine learning (ML) approach that is validated using ICOS network flux data. In addition to meteorological data, remote sensing information is used as input to the ML model. The contribution of optical and radar data is evaluated.

Training and validation are performed on ICOS data, and we also compare the flux predicted by the model with the flux estimated by an accurate remotely sensed crop model, SAFYE-CO2.

This study is part of our mission to provide operational tools to quantify the impact of agro-ecological practices on CO2 exchange and thus on soil organic carbon.

 

75 At-sea intercomparison of a membrane-based pCO2 sensor and a traditional showerhead equilibrator system

Poster

Vlad Macovei1*, Nathalie Lefèvre2, Denis Diverres3, Nadja Kinski4, Yoana Voynova1

1Helmholtz-Zentrum Hereon, Geesthacht, Germany. 2Sorbonne Université, CNRS, IRD, MNHN, LOCEAN/IPSL Laboratory, Paris, France. 3IRD Centre de Bretagne, IMAGO, IRD Centre de Bretagne, Technopole Brest Iroise, Plouzané, France. 44H-Jena Engineering GmbH, Kiel, Germany

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

The partial pressure of carbon dioxide in seawater (pCO2) is an essential ocean variable needed to calculate air-sea gas exchange and to identify marine carbon sinks and sources. Recent technological developments support autonomous pCO2 measurements with reduced size and cost sensors. In July 2021, different instruments were tested in a laboratory setting during the ICOS OTC Intercomparison, where a key message following the experiment was the need for further field comparisons. Here we present the results from a field test of two generations of 4H-Jena HydroC CO2-FT membrane-based sensors alongside a General Oceanics instrument that uses a more traditional equilibrator. The inter-comparisons were done onboard a Ship-of-Opportunity regularly travelling between Europe and South America. The first stage of the experiment took place in 2021, when the difference between the two instruments was within ± 10 µatm for 52% of the comparison time. For the second stage of the experiment, several improvements were made, including an automated cleaning routine, installation of a new membrane sensor prototype with the ability to measure a reference gas, better sensor temperature measurements and an updated data processing technique. Following the changes, the performance during the 2023 comparison improved to within ± 10 µatm for 94% of the comparison time with the mean difference being 1.8 ± 5.5 µatm. This experiment revealed that, with the required adaptations, membrane-based sensors can adequately measure seawater pCO2 at the Global Ocean Acidification Observing Network weather goal. 

 

76 Evaluating the consistency of methane emissions from regional inversions using different TROPOMI XCH4 satellite products

Poster

Aurélien Sicsik-Paré1*, Isabelle Pison1, Audrey Fortems-Cheiney1,2, Grégoire Broquet1, Élise Potier1,2, Robin Plauchu1, Adrien Martinez1, Florencio Utreras-Diaz3, Antoine Berchet1

1Laboratoire des Sciences du Climat et de l’Environnement, Gif-sur-Yvette, France. 2Science Partners, Paris, France. 3Universidad de Chile, Santiago, Chile

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The analysis of observations of total column methane atmospheric mixing ratios (XCH4) from satellites with atmospheric transport inverse modeling should strongly increase the capabilities to monitor the methane emissions at regional scale.

The TROPOspheric Monitoring Instrument (TROPOMI) on-board the Sentinel-5 Precursor (S5P) satellite launched in 2017 provides XCH4 with global daily coverage and a relatively high (5.5×7 km²) horizontal resolution. Widely used for the detection and inversion of XCH4 plumes associated to local super-emissions, TROPOMI-CH4 data is also exploited in regional and global flux inversions for the mapping of CH4 emissions.

Several products of XCH4 retrievals from the raw spectra measurements have been developed and they are routinely updated. The operational OFFL dataset is known to bear large biases. The SRON product relies on improved algorithms compared to OFFL, and on a correction for albedo-correlated bias. The WFMD product is based on the University of Bremen’s WFM-DOAS algorithm. The BLENDED product is a corrected version of the SRON product. The corrected bias is estimated with a machine learning model, which was trained to predict the differences between TROPOMI  and more mature GOSAT retrievals. Even if retrieval procedures have improved recently, previous intercomparison of the datasets revealed discrepencies at local and country scale.

We assimilate these four TROPOMI XCH4 products in atmospheric inversions of the regional emissions in Europe and South America in 2019 using the CHIMERE transport model, coupled to the inverse modeling platform Community Inversion Framework (CIF). Surface measurements are used as reference for validation. The presentation first focuses on the inversions for Europe at 0.5°×0.5° resolution. Secondly, we present results from the intercomparison of inversions for South America at 0.2°×0.2° resolution. 
   We will perform Observing System Simulation Experiments (OSSE) to estimate the uncertainties of retrieved fluxes and interpret differences between inversions. We plan to inquire into the impact of differences between XCH4 products on inversion results and retrieved methane fluxes at the local (pixel), country and regional scale.

 

77 Continuous CHcarbon isotope measurements in Italy: preliminary results from the Lampedusa observatory (Strait of Sicily) and general outline of the developing cross-country network

Poster

Francesco D&apos;Amico1,2*, Tatiana Di Iorio3, Giulia Zazzeri4, Damiano Sferlazzo3, Francesco Apadula4, Paolo Cristofanelli5, Claudia Roberta Calidonna1, Ivano Ammoscato1, Luana Malacaria1, Salvatore Sinopoli1, Lucia Mona6, Alcide Giorgio di Sarra3

1National Research Council of Italy - Institute of Atmospheric Sciences and Climate, Lamezia Terme, Italy. 2University of Calabria - Department of Biology, Ecology and Earth Sciences, Rende, Italy. 3Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Frascati, Italy. 4Ricerca sul Sistema Energetico, Milan, Italy. 5National Research Council of Italy - Institute of Atmospheric Sciences and Climate, Bologna, Italy. 6National Research Council of Italy – Institute of Methodologies for Environmental Analysis, Potenza, Italy

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Among greenhouse gases (GHG), methane (CH4) is showing several degrees of uncertainty and unpredictability in its patterns: though a clear upward trend driven by anthropic activities has been reported and is now well acknowledged, the source apportionment of methane emissions and major shifts in sink processes cannot be fully explained. Although a decreasing trend in the carbon 13 isotope ratio of methane (δ13C-CH4) might suggest an increased influence of biogenic sources to the total atmospheric budget in the past few years, the reasons behind this isotopic shift are still unknown. With climate change proceeding at a very fast pace, a detailed understanding of GHG budget is needed, and can be achieved by increasing the number of atmospheric stations that integrate carbon isotopes in their observations. The Italian branch of ICOS is now developing a cross-country network for this purpose. Here we present preliminary results from the Lampedusa observatory, located south of the Strait of Sicily and operated by the National Agency ENEA. A general outline of the developing network of atmospheric carbon isotope measurements in Italy is also presented: the Lampedusa observatory will be integrated into the network including Lamezia Terme (Calabria, Southern Italy) and Monte Cimone (Emilia-Romagna, Northern Italy), both operated by CNR-ISAC, as well as Potenza (Basilicata, Southern Italy), operated by CNR-IMAA. Each observatory has distinct environmental peculiarities and isotopic data gathered from the developing network are expected to contribute significantly to our knowledge of methane sources and sinks in the central Mediterranean Sea area.

 

78 Estimation of Net Ecosystem Exchange (NEE) over Europe for 2018 using Community Inversion Framework (CIF) - STILT

Poster

Eldho Elias1*, Antoine Berchet2, Saqr Munassar1, Frank-Thomas Koch1,3, Christoph Gerbig1

1Max Planck Institute for Biogeochemistry, Jena, Germany. 2Laboratoire des Sciences du Climat et de l&apos;Environnement, CEA-CNRS-UVSQ, Gif-sur-Yvette, France. 3Deutscher Wetterdienst, Hohenpeißenberg, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Atmospheric inversions have been widely used to understand and quantify the fluxes of greenhouse gases (GHGs) in the atmosphere, both in global and regional scales. The Community Inversion Framework (CIF) is an effort to bring multiple atmospheric inversion schemes under a comprehensive framework to estimate the fluxes of various GHGs and reactive species both at the global and regional scales (Berchet et al., 2021). In this study, we used the Lagrangian transport model STILT within CIF and performed CO2 inversion over Europe for the year 2018 by using observations from 44 ICOS stations. Hourly Net Ecosystem Exchange (NEE) calculated with VPRM is optimized in the inversions while anthropogenic emissions from EDGAR and ocean fluxes from Fletcher et al., (2007) are prescribed. The surface sensitivities “footprints” were pre-calculated by STILT, driven by meteorological forecasting fields from ECMWF. The results from the CIF-STILT inversions were compared with corresponding estimates done by Munassar et al., (2023) wherein CO2 inversions with a similar setup were carried out using the Jena Carboscope Regional (CSR) and LUMIA inversion systems. The similarities in the results as well as the potential causes for differences are assessed.

 

79 Potential response of the Baltic Sea Carbon Cycle to Extreme Events

Poster

Anna Rutgersson*, Erik Nilsson, John Prytherch

Uppsala, Uppsala, Sweden

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Marginal seas are a dynamic and still to large extent uncertain component of the global carbon cycle.  As the biological activity in general is high, they represent a relatively large part of the global carbon cycle. While continental shelves represent 7 % of the oceanic surface area, they are estimated to contribute to approximately 15% of the open ocean sink. In general, coastal seas show a high variability of the CO2 system. This high variability, generated by the complex mechanisms driving the CO2 fluxes, complicates the accurate estimation of these mechanisms. This is particularly pronounced in the Baltic Sea, a semi-enclosed sea at high latitudes, with very variable atmospheric forcing and a strong seasonal cycle. A number of studies have evaluated whether the Baltic Sea is a sink or source of carbon changes with climate without a clear consensus, for this it is also important to understand how the Baltic Sea carbon cycle responds to extreme events. By using 15 years of data from the marine ICOS-site Östergarnsholm we evaluate the impact on surface concentration of carbon dioxide (used as an indicator of the carbon response) of warm/cold seasons and high/low wind seasons in addition to changes in the upwelling frequency. 

 

80 Radiocarbon Isotopic Disequilibrium Shows Little Incorporation of New Carbon in Mineral Soils of a Boreal Forest Ecosystem

Oral

Andres Tangarife-Escobar1*, Georg Guggenberger2, Xiaojuan Feng3, Estefania Muñoz1,4, Ingrid Chanca1,5,6, Matthias Peichl7, Paul Smith8, Carlos Sierra1

1Max Planck Institute for Biogeochemistry, Jena, Germany. 2Leibniz Universität Hannover, Hannover, Germany. 3Chinese Academy of Sciences, Beijing, China. 4CREAF, Barcelona, Spain. 5Laboratoire des Sciences du Climat et de l’Environnement, Gif-sur-Yvette, France. 6Universidad Federal Fluminense, Niterói, Brazil. 7Swedish University of Agricultural Sciences, Umeå, Sweden. 8Swedish University of Agricultural Sciences, Vindeln, Sweden

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Abstract Text

Boreal forests fix substantial amounts of atmospheric carbon (C). However, the timescales at which this C is cycled through the ecosystem are not yet well understood. To elucidate the temporal dynamics between photosynthesis, allocation and respiration, we assessed the radiocarbon (14C) disequilibrium (D) between different C pools and the current atmosphere to understand the fate of C in a boreal forest ecosystem. Samples of vegetation, fungi, soil and atmospheric CO2 were collected at the Integrated Carbon Observation System (ICOS) station Svartberget (SVB) in northern Sweden. Additionally, we analysed the Δ14C-CO2 from incubated topsoil and forest floor soil respiration (FFSR) over a 24-hour cycle and calculated the Δ14C signature of the total ecosystem respiration (Re) using a Miller-Tans plot. We show that vegetation pools presented a positive D enriched with bomb 14C, suggesting a fast-cycling rate (in the order of months to years) for living biomass and intermediate (years to decades) for dead biomass. In contrast, mineral soils showed a negative D, indicating minimal incorporation of bomb 14C. FFSR showed diurnal Δ14C variability with an average value (mean = 8.5‰), suggesting predominance of autotrophic respiration of recently-fixed labile C. Calculations for Δ14C in Re (median = 12.71‰) demonstrate the predominance of C fixed from days to decades. Although the boreal forest stores significant amounts of C, most of it is in the soil organic layer and the vegetation, where it is cycled relatively fast. Only minimal amounts of recent C are incorporated into the mineral soil over long timescales.

 

81 Integrating Ameriflux Data in the CarbonSpace Platform

Oral

Andrey Dara*, Robert Granat, Rafael Fabbrini, Nathan Streisky, Geza Toth

CarbonSpace Ltd, Dublin, Ireland

Session 14. Leveraging Direct Flux Measurements Beyond Academia for Real-World Applications

CarbonSpace, an innovative online cloud-based platform, revolutionizes the estimation of CO2 fluxes by harnessing optical satellite imagery and advanced meteorological reanalysis data through machine learning regression. Our unique process combines bottom-of-atmosphere surface reflectance and land surface temperature from Landsat bands with select AgERA 5 variables, creating robust predictor variables. Net Ecosystem Exchange (NEE) from the Fluxnet2015 dataset serves as a reference of our estimates.

Our approach has contributed to reliable assessments in Nature-Based Solutions (NBS) projects and agricultural plantations. Leveraging Landsat imagery, CarbonSpace achieves a spatial resolution of up to 30 meters, with flux estimates generated monthly. Fluxnet&apos;s network, featuring 212 eddy-covariance towers spanning diverse biomes and land covers, underpins our data&apos;s reliability.

Through station-stratified cross-validation, we demonstrate our model&apos;s capability to accurately estimate carbon fluxes across different regions with similar land cover types, even in the absence of local flux towers. However, the density and distribution of these towers in certain biomes influence the precision of remote sensing-based estimations.

Our platform allows for the integration of new datasets, enhancing our estimation capabilities. In this presentation, we demonstrate improvements achieved by incorporating Ameriflux data into our reference framework and make the case for expansion of flux networks to generate robust, global estimates of GHG fluxes.

 

82 Artificial Neural Networks to estimate XCO2 from OCO-2 space-borne observations

Oral

Cédric Bacour*, François-Marie Bréon, Frédéric Chevallier

LSCE, Gif-sur-Yvette, France

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

We have developed an Artificial Neural Networks (ANN)-based processing chain for the
   estimate of XCO2 from OCO-2 observations over land surfaces. The ANN training
   combines real OCO-2 L1b observations with XCO2 estimates from the CAMS (Copernicus
   Atmosphere Monitoring Service) modeling. The retrieval accuracy and precision are
   comparable to or better than the official retrieval algorithm (ACOS), which relies on full-
   physics radiative transfer model inversion and subsequent empirical bias correction, for
   soundings within the ANN training period. In addition, the ANN is also capable of
   representing small scale features (plumes) that are generated by strong localized
   emissions and which are not embedded in the CAMS database used for the training.

However, we observed degraded performance when the ANN is applied to observations
   acquired over a time period not included in the training database (as for instance one
   missing year in the middle of the training period). For near-real time processing, where
   observations inherently extend beyond the training period, the challenge of extrapolation
   for ANN becomes even more critical. We have observed that for soundings acquired one
   year after the end of the training period, the retrieval bias is on the order of the
   atmospheric CO2 concentration growth rate (of 2.5 ppm).

We will present the ANN retrieval approach and assess the performance of the ANN-
   based XCO2 estimates in comparison to the ACOS product. We will outline the current
   limitations of the approach and discuss ongoing research efforts aimed at mitigating the
   observed generalisation issue.

 

83 Variability of surface seawater fCO2 in the coastal region off Brazil sampled by the France-Brazil ICOS Station

Poster

Nathalie Lefevre1*, Manuel Flores Montes2, Lucas Medeiros2, Denis Diverres3

1IRD-CNRS-SU-LOCEAN, Paris, France. 2UFPE, Recife, Brazil. 3IRD-IMAGO, Plouzane, France

Session 7. Carbon Cycling along the Land Ocean Aquatic Continuum

The fugacity of CO2 (fCO2) has been measured underway in the ocean and in the atmosphere on board a merchant ship sailing from Europe to South America since 2008. This ship of opportunity line is part of the ICOS network. During its journey, the ship samples a wide range of oceanic provinces. This line has a particular interest as it samples the South Atlantic, a poorly documented region. Here we focus on the region close to the coast of Brazil from 12oS to 4oS. We have used 78 voyages made from 2008 to 2023 to examine the fCO2 variability as a function of latitude and longitude. Two distinct regions are identified north and south of 8oS. The water mass from 12oS to 8oS comes from the southern branch of the South Equatorial Current (SEC), whereas further north (8oS-4oS), the central branch of the SEC explains the higher fCO2 values and the lower surface salinity. Both regions are a source of CO2 to the atmosphere, with stronger CO2 outgassing occurring north of 8oS. The voyages from 12oS to 8oS show a cross-shore variability with a significant increase of fCO2 towards the open ocean, and a significant decrease of surface salinity (p-value<0.05). The offshore decrease of salinity is also evidenced on the satellite salinity from SMOS. The ocean surface circulation is likely responsible for the different patterns observed in this region.

 

84 environmental monitoring of coal mining area: Lessons learned from ground-based ch4 measurements

Oral

Yaroslav Bezyk1, 2*, Jarosław Necki1, Miroslaw Zimnoch1, Paweł Jagoda1, Jakub Bartyzel1, Carina van der Veen3, Thomas Röckmann3

1AGH University of Krakow, Krakow, Poland. 2Wroclaw University of Science and Technology, Wrocław, Poland. 3Utrecht University, Utrecht, Netherlands

Session 1. Isotopes and other tracers for studies of methane sources and sinks

The Upper Silesian Coal Basin in Poland is known for persistent enhancement of methane visible from space. Therefore, creating a reliable CH4 inventory for underground coal mines requires accurate in-situ measurements of associated emissions, with particular attention to stable isotope signatures of the source. The analysis is based on three intensive measurement campaigns, initiated in June and October 2022, and continued in June 2023, along with monthly mobile monitoring of coal mining methane trends from active and abandoned coal mines spanning from February 2023 to January 2024. 

The temporal and spatial variability of CH4 levels in USCB, obtained from ground-based surveys of individual ventilation shafts, is combined with the Gaussian plume model and the EPA OTM-33A method. The mobile platform includes the LGR MGGA918, Licor 7810, Picarro G2201-i isotope analyzer. The results reveal an enhancement of CH4 (from 2.1 to 6.4 ppm) in the plumes detected several kilometres downwind of active ventilation shafts in most study cases. The estimated methane emission rate, which varies depending on the examined shaft, falls within range between 103±32 kg/h and 1490±634 kg/h. 

In comparison, the data collected during the surveys near abandoned coal mines under different weather conditions (cyclonic and anticyclonic circulations) did not indicate a significant methane plume from the non-active mining area. The isotope signatures (–49.1±1.9 ‰ for δ13C; –182.2±14.7 ‰ for δ2H) of CH4 in the near-source plumes, calculated using the Keeling plot approach, suggest a primarily thermogenic origin of the coalbed gas in the USCB region. 

 

85 Evaluation of the nitrogen oxide emission inventory with TROPOMI observations

Poster

Chian-Yi Liu*, Yi-Chun Chen, Charles Chou

Academia Sinica, Taipei, Taiwan

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

To compensate for the emissions missed or underestimated in the national bottom-up emission inventories, we apply the high spatial resolution satellite data from TROPOspheric Monitoring Instrument (TROPOMI) to estimate the top-down nitrogen oxide (NOx) emissions in regional scales. The NOx chemical lifetime is derived based on ground-based measurements of ozone photolysis rate, ultra-violet (UV) index, and temperature. For five designated regions of western Taiwan, the derived lifetime is about 1–2 h in summer and 2–4 h in winter. The retrieved 2021 annual emissions for regions near two major pollution sources, Taichung thermal power plant and Mailiao Industrial Zone, are comparable with the emission from the Continuous Emission Monitoring System (CEMS), with a difference of 6% and -12%, respectively. After validating the data and methods, the NOx emissions for five regions of western Taiwan are derived and applied to evaluate the bottom-up inventories. For northern and southern Taiwan, the top-down emissions agree well with emission inventories. The top-down emissions are 12%, 23%, and 16% higher than emission inventories for north-central, central, and southcentral Taiwan, respectively. This indicates that the bottom-up inventories are underestimated from northcentral to south-central Taiwan, which may be associated with the uncertainties from traffic sources. Given the various complex pollution sources, deriving NOx emissions from space allows us to acquire a better understanding of emissions on urban scales and improve the bottom-up emission inventories.

 

86 Analysis of urban CO2 and heat fluxes and evaluation of the SUEWS model using eddy covariance observations from two towers in Heraklion, Greece.

Poster

Konstantinos Politakos1*, Emmanouil Panagiotakis1, Dimitris Tsirantonakis1,2, Stavros Stagakis1,3, Nektarios Spyridakis1, Christian Feigenwinter3, Matthias Roth4, Nektarios Chrysoulakis1

1Remote Sensing Lab, Institute of Applied and Computational Mathematics, Foundation for Research and Technology – Hellas (FORTH), Heraklion, Crete, Greece. 2Chair of Environmental Meteorology, Faculty of Environment and Natural Sciences, University of Freiburg, Freiburg, Germany. 3Department of Environmental Sciences, University of Basel, Basel, Switzerland. 4Department of Geography, National University of Singapore, Singapore, Singapore

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Urbanization drives global CO2 levels higher, mainly due to human activities like fossil fuel combustion for heating, industry, and transportation. Emissions vary spatially based on factors like population density, land use or urban structure, underscoring the need to measure and understand local emissions to manage city-wide carbon budgets. The present study analyzes CO2, sensible and latent heat fluxes from two ICOS Associated eddy covariance flux towers in the city of Heraklion, Greece. Despite their proximity, only 1.5 km apart from each other, HECKOR and HECMAS represent distinct land use types: HECKOR is in the commercial city center, while HECMAS is in a residential area. Seasonal and diurnal CO2 flux patterns are therefore significantly different across the sites. HECKOR&apos;s fluxes align with commercial and working hours year-round, while HECMAS primarily captures CO2 emissions from residential heating during winter with only small fluxes during other times of the year. Furthermore, there is extreme directionality in CO2 fluxes measured in HECKOR, and thus the estimated diurnal patterns are affected by the seasonality of wind direction patterns. Dynamic flux footprints from both towers are analyzed to link observed CO2 fluxes to specific land use and land cover features. Additionally, we utilize the latest SUEWS CO2 modeling module, integrating TomTom traffic data and flux footprints to assess surface emissions alongside in-situ flux tower data. We also observe higher sensible heat fluxes in HECKOR, most probably due to higher building density and lower vegetation cover in the Heraklion central commercial district. 

 

87 European methane flux estimates for 2022 based on the Radon Tracer Method, regional atmospheric inversions and inventories

Poster

Camille Yver-Kwok1*, Isabelle Pison1, Antoine Berchet1, Grégoire Broquet1, Grant Forster2, Audrey Fortems-Cheiney1, Arnoud Frumau3, Dagmar Kubistin4, Matthias Lindauer4, Morgan Lopez1, Jennifer Müller-Williams4, Michel Ramonet1, H. A. Scheeren5, Aurélien Sicsik-Paré1, Martin Steinbacher6

1LSCE, Gif-sur-Yvette, France. 2UEA, Norwich, United Kingdom. 3TNO, Petten, Netherlands. 4DWD, Hohenpeissenberg, Germany. 5CIO, Groningen, Netherlands. 6EMPA, Dübendorf, Switzerland

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The Integrated Carbon Observation System (ICOS) is a European research infrastructure, which provides compatible, harmonized and high-precision scientific data on the carbon cycle and greenhouse gases (GHGs). Its atmospheric component consists of 39 stations predominantly located in Europe. Within ICOS atmosphere stations, CH4 measurements are mandatory, while 222Rn measurements are recommended.

Methane is the second most important anthropogenic GHG after CO2 and is emitted by multiple sources whose locations and magnitude still remain incomplete.

222Rn is not a GHG but it is emitted naturally in a relatively diffuse way from rocks and soils. With a lifetime of a few days, it serves as a proxy for surface-atmosphere interaction and, consequently, as a tracer for atmospheric transport and mixing studies. The Radon Tracer Method (RTM) combines radon and GHG observations to derive estimates of GHG fluxes at local to regional scale.

In this work, we compare the methane flux estimates for Europe in 2022 obtained from three different methods. 1) the RTM applied to methane and radon data from 16 ICOS stations combined with radon exhalation maps and simulation of the station atmospheric footprints 2) atmospheric inversions based on the Community Inversion Framework coupled to the regional-transport model CHIMERE, assimilating either the methane mixing ratio from the same ICOS stations, or total columns CH4 observation from the TROPOMI satellite instrument 3) an extraction of the anthropogenic emissions from inventories such as EDGAR and TNO.

 

88 A new IFS 125HR FTIR instrument for the measurement of trace gases over the Po Valley

Poster

Paolo Pettinari*, Elisa Castelli, Enzo Papandrea, Bianca Maria Dinelli, Angela Marinoni, Paolo Cristofanelli, Francescopiero Calzolari, Claudio Campenni

CNR-ISAC, Bologna, Italy

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

In the frame of the ITalian INtegrated Environmental Research Infrastructures System (ITINERIS), the Italian research institute CNR-ISAC will acquire a new Bruker IFS 125HR FTIR spectrometer in the next year. 

The IFS 125HR instrument will be installed in Bologna and will be equipped with all the accessories necessary to make its spectra compliant to its dedicated global measurement networks: the Network for the Detection of Atmospheric Composition Change (NDACC) and the Total Carbon Column Observing Network (TCCON).

Its measurements will be used to retrieve information on several trace gases such as: O3, HNO3, HCl, HF, CO, N2O, CH4, HCN, C2H6, ClONO2, CO2, H2O, O2 and HDO. In particular, the high spectral resolution of its measurements will allow to retrieve information on different atmospheric layers for most of the mentioned species. This information, together with the one obtained with the operative instruments already present at the institute, are useful for the monitoring of air quality in the Po Valley. Moreover, their compliances to the mentioned global networks will make these measurements particularly suitable also for the validation of satellite data.

 Here, we present the potentials of the IFS 125HR FTIR instrument within the ITINERIS project.

 We thank the support of the Italian Ministry for Universities and Research through IR0000032 – ITINERIS, Italian Integrated Environmental Research Infrastructures System (D.D. n. 130/2022 – CUP B53C22002150006) Funded by EU – Next Generation EU PNRR – Mission 4 “Education and Research” – Component 2: “From research to business” – Investment 3.1.

 

89 Trees functioning under excess or lack of water

Poster

Paulina Dukat1*, Teemu Holtta1, Timo Vesala1, Marek Urbaniak2, Yann Salmon1, Julia KELLY3, Johannes EDVARDSSON3, Irene LEHNER3, Anders LINDROTH3, Natasha KLJUN3, Ram Oren4, Anna Lintunen1

1University of Helsinki, Helsinki, Finland. 2Poznan University of Life Sciences, Poznan, Poland. 3Lund University, Lund, Sweden. 4Duke University, Duke, USA

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

In the era of changing climate and the increasing intensity of extreme phenomena on a global scale, it has become particularly important to understand the response of widely distributed plant species 
   to changing living conditions and various types of stresses. Scots pine and silver birch are adapted to and widespread in both boreal and temperate regions. In the boreal and temperate regions, extreme phenomena are observed that have not occurred with such frequency and intensity in the past, especially droughts, floods and wildfires. In the presented work, we focused on the aspects of lack and excess of water, which lead to similar disturbances in the functioning of trees. Lack of oxygen for the tree roots means problems with energy production and disturbs sap flow and, consequently, transpiration, as does the lack of water.Scots pine and silver birch have been found to grow in drought-prone conditions (e.g., central Poland, central Germany), as well as in wet and flooded zones (e.g,  Finnish wetlands). The aim of the study was to assess the transpiration, productivity and resource use capacity of Scots pine and silver birch in various environmental conditions. Trees growing on the bog-forest transect (in Southern Finnland) and trees in areas with annual rainfall falling below 400 mm (in central Poland) were used. We also present results concerning tree transpiration and productivity obtained from a Scots pine forest after a low severity wildfire (in central Sweden). 

 

90 Understanding Variability in Methane Flux Measurements: Results from an Expert Survey on Chamber Flux Methods

Poster

Claire Treat1*, Katharina Jentzsch1, Nicholas Nickerson2, Lona van Delden1, Matthias Fuchs3, Pamela Baur4, Julia Boike1, Jill Bubier5, Jesper Christiansen6, Scott J. Davidson7, Bo Elberling6, Stephan Glatzel4, Kathleen Hall8, Paul Hanson9, Nicholas Hasson10, Liam Heffernan11, Jacqueline Hung12, Vytas Huth13, Gerald Jurasinski14, Sari Juutinen15, Masako Kajiura16, Evan Kane17, Aino Korrensalo18,19, Genevieve Noyce20, Frans-Jan Parmentier21, Matthias Peichl22, Norbert Pirk21, Maria Strack23, Eeva-Stiina Tuittila19, Ruth Varner24, Anna-Maria Virkkala12, Carolina Voigt25, Lei Wang26

1AWI, Potsdam, Germany. 2Eosense Inc., Darmouth, Canada. 3University of Colorado at Boulder, Boulder, CO, USA. 4University of Vienna, Vienna, Austria. 5Mount Holyoke College, South Hadley, MA, USA. 6University of Copenhagen, Copenhangen, Denmark. 7University of Plymouth, Plymouth, United Kingdom. 8University of Rochester, Rochester, NH, USA. 9Oak Ridge National Lab, Oak Ridge, TN, USA. 10University of Alaska Fairbanks, Fairbanks, AK, USA. 11Uppsala University, Uppsala, Sweden. 12Woodwell Climate Research Center, Woods Hole, MA, USA. 13University of Rostock, Rostock, Germany. 14University of Greifswald, Greifswald, Germany. 15Finnish Meteorological Institute, Helsinki, Finland. 16National Agriculture and Food Research Organization, Tsukuba, Japan. 17Michigan Technological University, Houghton, MI, USA. 18Natural Resources Institute Finland, Joensuu, Finland. 19University of Eastern Finland, Joensuu, Finland. 20Smithsonian Environmental Research Center, MD, USA. 21University of Oslo, Oslo, Norway. 22Swedish University of Agricultural Sciences, Umea, Sweden. 23University of Waterloo, Waterloo, ON, Canada. 24University of New Hampshire, Durham, NH, USA. 25Universität Hamburg, Hamburg, Germany. 26Beijing Normal University, Beijing, China

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

Advances in laser spectroscopy have improved the analysis of key trace gases like CH4 and N2O, opening new possibilities through both portability and with reduced measurement times using high-frequency (>1 Hz) data. However, high-frequency and high-accuracy CH4 concentration measurements also pose challenges in the interpretation of CH4 fluxes due to non-linear behavior from earlier protocols using longer measurement times with fewer samples. Here, we used a community survey to investigate the approaches for chamber fluxes used by different researchers. We received nearly 40 responses indicating that ~75% of respondents have adopted high-frequency, multi-gas analyzers with most measurement times between 2-5 minutes. We presented a standardized set of CH4 concentrations from observed flux measurements and asked about their approach to quality control and flux calculations. We found strong agreement among the experts when CH4 fluxes exhibited linear behavior but two main approaches for non-linear fluxes. Many survey respondents discarded the initial part of the measurements due to initial disturbance related to chamber placement, while roughly the same number selected the initial part and discarded the later part of the measurements due to chamber saturation effects. Experts also strongly disagreed on the inclusion of fluxes around zero. Our study shows the need to understand drivers of the patterns visible from high-resolution analyzers and standardized procedure and guidelines for future chamber CH4 flux measurements. This is highly important to reliably quantify methane fluxes all over the world and, especially in Arctic regions where we expect the greatest changes in the near future.

 

91 Greenhouse gases emission and absorption in an extensive young walnut orchard (Juglans regia L.) in Italy

Poster

Marianna Nardino1*, Lorenzo Brilli2, Federico Carotenuto1, Daniela Famulari1, Lorenzo Fiorini1, Beniamino Gioli2, Alessandro Zaldei2, Camilla Chieco1

1CNR-IBE, Bologna, Italy. 2CNR-IBE, Florence, Italy

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

The role of agriculture in carbon (C) balance is still contrasting, since this sector can act as both a contributor to greenhouse gas emissions and a potential sink for carbon. In this perspective, field research activities aimed at measuring fluxes from agricultural systems should be implemented, particulralyover long-term agroecosystem such as orchards, where C can be stocked in woody compartments and soil for long time. 

In this context, the first year of an experimental campaign over a 170-hectare wide plot of young (three-years) walnut trees (Juglans regia L.) is currently running in Bondeno (Emilia Romagna, Italy), to measure the GHG fluxes from this system. 

The C-fluxes (Net ecosystem exchange, NEE) are measured using eddy covariance, while N2O emission are measured using real-time portable N2O trace gas analyzer (LI-7820 N2O /H2O, Li-Cor) connected with an automated soil chamber (LI-8200-01S Smart Chamber, Li-Cor). While C-fluxes are collected at high-frequency (30-min), N2O fluxes were measured along the growing season at monthly intervals and intensively after each mineral fertilization event. The total yearly GHG balance of the wall tree system is then expressed as CO2eq. 

Preliminary results indicate that extreme and mean weather conditions coupled with agricultural practices (i.e, fertilization, tillage, pruning, etc.) may affect from daily to monthly C-N fluxes, strongly influencing the overall yearly GHG balance of the system.

 

92 Carbon and water relations over three growing seasons in an African arid Savanna and grassy shrubland.

Poster

Amukelani Maluleke1*, Gregor Feig1,2, Christian Brümmer3, Tamryn Hamilton4, Abraham de Buys1, Guy Midgley5

1South African Environmental Observation Network, Pretoria, South Africa. 2Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Pretoria, South Africa. 3Thünen Institute of Climate‐Smart Agriculture,, Braunschweig, Germany. 4North-West University, Potchefstroom, South Africa. 5Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Anthropogenic climate change and increasing atmospheric carbon dioxide could alter ecosystem and biogeochemical processes in African drylands, potentially affecting land-atmosphere feedbacks. We used a paired-site Eddy Covariance-based approach to compare carbon and water exchange in Savanna and Nama-Karoo biomes, revealing differences in phase and magnitude in carbon fluxes across multiple scales. A Total of -160 g C m-2, was recorded at the Nama Karoo Site, versus a total of -567 g C m-2  over a period of 33 months, with mean annual NEE of -189g C m-2 y-1 and -53 g C m-2 y-1 for the Savanna and Nama Karoo sites, respectively. More carbon uptake was observed during periods of intermediate soil moisture at both sites, with soil moisture also observed to modulate the relationship between nighttime NEE and soil temperature. The rainfall required to trigger ecosystems (and initiate the start of the growing season) into carbon sinks varied across periods, with the Savanna site requiring between 131 mm and 172 mm, and the Nama-Karoo site requiring between 98 mm and 165 mm. A fire event in the second period nearly halved carbon uptake compared to the first period at the Savanna site, also delaying the start of the growing season even with higher rainfall received. The Nama-Karoo site had higher ecosystem water use efficiency (eWUE), but more variability in eWUE was observed at the Savanna site. Both vegetation types were consistent net carbon sinks over three growing seasons, with contrasts in functioning observed under similar climatic conditions.

 

93 Urban and tropical EM27/SUN network for satellite validations, observations and verification of greenhouse gas emissions

Poster

Morgan Lopez1*, Macquart Benoit1, Simona Latchabady1, Josselin Doc1, Laura Ticone2, Benoit Burban3, Lynn Hazan1, Michel Ramonet1

1LSCE, Gif-sur-Yvette, France. 2Laboratory of atmospheric physics, La Paz, Bolivia, Plurinational State of. 3INRAE, Kourou, France

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

The EM27/SUN instrument is a FTIR spectrometer allowing to retrieve total atmospheric column abundance of CO2, CH4, CO and H2O. LSCE is currently involved in two projects in which the EM27/SUN instruments are deployed in different environments for different purposes.

The OBS4CLIM project aims at deploying five EM27 by 2023 at observatories located in tropical (Bolivia, French Guiana, Morocco, Ivory Coast) and background regions (Amsterdam Island, Indian Ocean) for long-term observations and satellite validation purposes.

The ICOS-Cities project aims at evaluating different observational approaches to determine CO2 emissions from large cities, such as Paris. A chosen strategy consists in evaluating the Paris carbon budget by coupling total column measurement to inverse modeling. For that purpose, two EM27s are deployed in a north to south transect of Paris, in addition to the Paris TCCON site.

The rapid growth of this EM27/SUN network requires developing tools to ensure data quality and availability. Therefore, LSCE has developed:

  • An automatic data treatment chain based on PROFFAST (developed and maintained at KIT). Two models are used as a priori profiles (GGG2020, and CAMS) allowing to retrieve daily data in near real-time (NUBICOS project).
  • Automatic enclosure systems to protect the instrument from a rough environment. This system allows increasing drastically the daily observations and data availability.

We will present in detail the two major developments done at LSCE and necessary to obtain a robust network providing semi-continuous observations in near real time. Results from the OBS4CLIM and ICOS-Cities projects will also be detailed. 

 

94 VERBE - Towards a greenhouse gas emission monitoring and Verification system for Belgium

Poster

Filip Desmet1,2*, Sieglinde Callewaert1, Minqiang Zhou1,3, Jiaxin Wang3, Yvan Nollet1, Nicolas Kumps1, Bart Dils1, Mahesh Kumar Sha1, Bert Gielen2, Bernard Heinesch4, Martine De Mazière1

1Royal Belgian Institute for Space Aeronomy, Brussels, Belgium. 2University of Antwerp, Antwerp, Belgium. 3Institute of Atmospheric Physics, Beijing, China. 4University of Liège, Liège, Belgium

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

Like most countries, Belgium’s national greenhouse gas inventory report to the United Nations Framework Convention on Climate Change is based on a bottom-up approach which combines statistical data about economic activities with activity-specific emission factors to calculate the total emissions. It has been shown that it is possible to improve the understanding of the national reporting by adding complementary information obtained using a top-down approach, combining atmospheric greenhouse gas observations with an inverse modelling framework.

VERBE (https://verbe.aeronomie.be) aims to develop such a system tailored for Belgium, and will combine satellite and ground-based infrared remote-sensing and ICOS in-situ observations with inverse modelling. Such in-situ and FTIR observations will be established in Belgium. The universities of Antwerp and Liège share their ecosystem (vegetation and soil) exchange modelling experience to provide biogenic fluxes, that will be combined with anthropogenic emission inventories to provide a-priori emissions. Those will be used with atmospheric transport and inversion models running at BIRA-IASB to provide a-posteriori emissions.

The VERBE project (01/09/2022 - 01/12/2026) supports the FED-tWIN research BE-MVS (A BElgian greenhouse gas emissions Monitoring and Verification System), and collaborates with colleagues developing similar systems in Germany and the Netherlands.  The approaches of the UK and Switzerland, which have published top-down emission estimates for hydrofluorocarbons, CH4, N2O and CO2 (UK) in the annexes of their latest reports, are also studied.

This poster gives an overview of the objectives of VERBE, and shows preliminary results of an FTIR measurement campaign around the city and port of Antwerp in April 2024.

 

95 Inverse modelling of regional methane emissions from multiple sources using high frequency methane isotope observations

Oral

Alice Ramsden1*, Anita Ganesan2, Tim Arnold3,4, Emmal Safi3, Chris Rennick3, Edward Chung3, Dave Lowry5, Simon O&apos;Doherty2, Dickon Young2, Joseph Pitt2, Kieran Stanley2, Alistair Manning1, Matt Rigby2

1Met Office Hadley Centre, Exeter, United Kingdom. 2University of Bristol, Bristol, United Kingdom. 3National Physical Laboratory, Teddington, United Kingdom. 4School of Geosciences, University of Edinburgh, Edinburgh, United Kingdom. 5Royal Holloway University of London, London, United Kingdom

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Top-down inverse models can be used to estimate regional methane emissions, by combining high frequency methane concentration observations with output from an atmospheric transport model. These methods traditionally produce a monthly or annual estimate of total regional methane emission from all sources. However recent developments in this field, including those presented here, use observations of methane isotopes within the inverse model to directly estimate methane emissions from different sources.

Here, we present results from a Bayesian inverse modelling system that incorporates new high-frequency observations of both δ13C(CH4) and δ2H(CH4) from the Heathfield tall tower observation site in the south-east UK to estimate emissions from two broad source sectors. Methane isotope ratios used to characterise emissions sources can be uncertain and vary spatially and temporally. So this inversion method also optimises these isotope ratios simultaneously with emissions, whilst considering the uncertainty in all these variables.

We demonstrate the potential for this method to be used with an expanded network of methane isotope instruments across the UK. We then present fossil fuel and agricultural and waste emissions estimates for southern England from the inverse model with currently available high frequency isotope observations. We find that using both methane isotope and ethane observations together in the model provides a greater constraint on emissions from the fossil fuel sector and reduces overall uncertainty in the sector-level methane flux estimates.

 

96 Working with C stock of soils in partly vegetated boreal/arctic environment and relation to landscape parameters.

Poster

Jón Guðmundsson*, Fanney Ósk Gísladóttir

Agricultural university of Iceland, Borgarbyggð, Iceland

Session 13. In situ data for climate and other environmental services and policy support

One way to estimate GHG fluxes on terrestrial ecosystems is to record stock changes either as difference in stocks over a period of several years, or through chrono sequential rows shifting time with place, when dealing with fixed management regimes of different age. The chrono sequential approach requires series of sites under the same management that have started on land that in principle was identical regarding C stock. In cases where these conditions are not met, direct flux measurements or stock comparation are two remaining alternatives. Confronted with the task of  evaluating carbon budget of extended grazing land with free roaming sheep grazing and basically no background information on carbon stock it was decided to start building a baseline for the stock evaluation. Extensive soil sampling scheme was set up and over ten years period (2007-2017) around 2000 locations were visited (Gudmundsson et al. 2021). At each location information on vegetation total cover and separated to functional categories, erosion marks, soil depth and land cover category was recorded, and soil and aboveground biomass sampled. Data analyses are still pending. As all locations are georeferenced our data can be directly connected to available or obtainable geographic attributes potentially aiding in explaining the pattern observed.  We hereby offer for cooperation, sharing and analyses of the data in IGLUD database. 

 

98 A world of hexagons on graphics processing units: new numerical paradigms for atmospheric inversion

Poster

Frédéric Chevallier*, Sakina Takache, Zoé Lloret, Anne Cozic, Adrien Martinez, Yann Meurdesoif

LSCE, Gif-sur-Yvette, France

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The coming exascale era of supercomputing offers a major opportunity to significantly increase the spatial resolution of global atmospheric inversion and thereby significantly improve current scientific capabilities for estimating greenhouse gas budgets at regional scale everywhere. However, the architecture of the new machines is primarily driven by Artificial Intelligence applications, rather than by scientific computing in the broad sense, and massively uses accelerated hardware such as GPU. Atmospheric inversion software must adapt to benefit from it. Here we present the design of the new CAMS CO2 inversion system which achieves a global resolution of 90 km (64,002 cells per vertical layer) on GPU-accelerated supercomputers while preserving the quarterly production rate for the Copernicus service: the code was ported to NVIDIA GPU devices and large-scale advection was rewritten to work on a Goldberg-polyhedron mesh, which exhibits no polar singularities unlike usual latitude-longitude meshes. The new code is faster, more compact, and more linear, and it runs efficiently on GPU at the desired resolution. When run at comparable resolution at the Equator, its simulations are very similar to the previous version, but they are still limited by the large volume of input meteorological data. We discuss its scalability from 180 km resolution to 90 km resolution, and the prospect of 22 km resolution, close to the native resolution of the underlying ERA5 reanalysis. Hardware and software environments are evolving rapidly and we also discuss future challenges for the code, including its portability given its current dependence on a specific vendor.

 

99 Spatial modelling of biogenic CO2 and heat fluxes in the city of Zürich

Poster

Anni Karvonen1*, Stuart K. Grange2, Minttu Havu1,3, Dominik Brunner2, Lukas Emmenegger2, Natascha Kljun4, Stavros Stagakis5, Leena Järvi1,6

1Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland. 2Empa, Laboratory for Air Pollution/Environmental Technology, Dübendorf, Switzerland. 3CNRM/Météo-France, Toulouse, France. 4Centre for Environmental and Climate Science, Lund University, Lund, Sweden. 5Department of Environmental Sciences, University of Basel, Basel, Switzerland. 6Helsinki Institute of Sustainability Science, University of Helsinki, Helsinki, Finland

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Cities are taking actions to mitigate their climate impact. Reducing carbon dioxide (CO2) emissions is crucial, but cities also need information about carbon sequestration. Green urban areas can be planned to maximize sinks and stocks of carbon, and in addition, they are crucial in reducing heat and enhancing cooling.

In this research, the city of Zürich, Switzerland, was modelled with the Surface Urban Energy and Water balance Scheme (SUEWS). This urban land surface model can simulate energy, water and CO2 exchanges. Furthermore, it produces temperature profiles in the roughness sublayer (RSL). To simulate integrated cycles, meteorological forcing data and information about urban surface cover, such as land surface types and their parameters, is needed. A spatial model run of the city using 250x250 m2 grids was done for the years 2022-2023, the first one being a spin-up. ICON-ART was used to produce meteorological forcing. The modeled air temperature was compared against the ICOS Cities rooftop sensor network, and modeled CO2, latent and sensible heat fluxes against eddy covariance (EC) measurements conducted at the 111 meter tall Hardau II tower.

Results show that SUEWS captures the temperature variations in different areas around the city. The EC fluxes are also well-simulated. The spatial biogenic CO2 maps give a sensible distribution of fluxes, meaning for example that the forests surrounding Zürich city center are the strongest sinks, but photosynthetic uptake also takes place in the more built-up areas. Later, canopy coverage will be linked with the modelled CO2 exchange and heat.

 

100 Eddy covariance measurements of Carbonyl sulfide (COS) to partition the urban carbon flux

Oral

Jesse Soininen1*, Kukka-Maaria Kohonen2, Pekka Rantala1, Liisa Kulmala3, Hermanni Aaltonen3, Stavros Stagakis4, Leena Järvi1,5

1Institute for Atmospheric and Earth System Research / Physics, Faculty of Science, University of Helsinki, Helsinki, Finland. 2Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland. 3Finnish Meteorological Institute, Helsinki, Finland. 4Department of Environmental Sciences, University of Basel, Basel, Switzerland. 5Helsinki Institute of Sustainability Science, University of Helsinki, Helsinki, Finland

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Cities are global hot spots of anthropogenic CO2 emissions, contributing over 70% of the global emissions. The heterogeneous urban ecosystems generate net CO2 fluxes (NEE) consist of many different anthropogenic and biogenic components, which cannot be distinguished from one another measuring only CO2 with eddy covariance technique. Carbonyl sulfide (COS) is a trace gas taken up through the same pathway as CO2 but not emitted back to the atmosphere. Hence, it can be used as a proxy for gross primary production (GPP). 

The aim of this work is to examine the suitability of COS flux measurements to partition GPP and other components from urban NEE. For this, intensive measurement campaigns were conducted at ICOS Associated Ecosystem Station FI-Kmp in Helsinki between summer 2023 and spring 2024, and in Zürich over winter 2022–2023. 

During the growing period, significant COS uptake associated with photosynthesis was observed in wind directions with high fraction of vegetated surfaces. In summer, in a highly vegetated urban area (Helsinki), we were able to successfully estimate GPP using COS flux and partition it from NEE. In wintertime, however, we saw an influence of anthropogenic emissions on COS fluxes, which complicates GPP estimates and sheds light on the details of global budget of COS, which has not been closed to the date. We show how COS based GPP estimates can be made in urban regions, but limitations on scale and accuracy need to be considered based on the flux source area.

 

101 Celebrating the Surface Ocean CO2 Atlas (SOCAT), a community-led synthesis, with WMO G3W on the horizon

Oral

Dorothee Bakker1, Tobias Steinhoff2*, Richard Sanders3, Adrienne Sutton4, Simone Alin4, Hermann Bange2, Nicholas Bates5,6, Meike Becker7,8, Richard Feely4, Thanos Gkritzalis9, Steve Jones7, Alex Kozyr10, Siv Lauvset3,8, Nicolas Metzl11, David Munro12,13, Shin-ichiro Nakaoka14, Kevin O&apos;Brien4,15, Are Olsen7,8, Denis Pierrot16, Gregor Rehder17, Colm Sweeney13, Maciej Telszewski18, Bronte Tilbrook19,20, Chisato Wada14, Rik Wanninkhof16, All SOCAT contributors1

1School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom. 2GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany. 3NORCE Norwegian Research Centre, Bergen, Norway. 4Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, USA. 5School of Ocean Futures, Julie Ann Wrigley Global Futures Laboratory, Arizona State University, Tempe, USA. 6Bermuda Institute of Ocean Sciences (BIOS), St Georges, Bermuda. 7Geophysical Institute, University of Bergen, Bergen, Norway. 8Bjerknes Centre for Climate Research, Bergen, Norway. 9VLIZ Flanders Marine Institute, Oostende, Belgium. 10Ocean Carbon Data System, National Centers for Environmental Information, National Oceanic and Atmospheric Administration, Knoxville, USA. 11Sorbonne Universités (UPMC, Univ Paris 06), CNRS, IRD, MNHN, LOCEAN/IPSL Laboratory, Paris, France. 12Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, USA. 13National Oceanic & Atmospheric Administration/Global Monitoring Laboratory (NOAA/GML), Boulder, USA. 14Earth System Division, National Institute for Environmental Studies, Tsukuba, Japan. 15Cooperative Institute for Climate, Ocean and Ecosystem Studies, University of Washington, Seattle, USA. 16Atlantic Oceanographic and Meteorological Laboratory, National Atmospheric and Oceanographic Administration, Miami, USA. 17Leibniz Institute for Baltic Sea Research Warnemünde, Rostock, Germany. 18International Ocean Carbon Coordination Project, Institute of Oceanology of the Polish Academy of Sciences, Sopot, Poland. 19CSIRO Environment, Castray Esplanade, Hobart, Australia. 20Australian Antarctic Partnership Program, Hobart, Australia

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The community-led Surface Ocean CO2 Atlas (SOCAT, www.info.socat) is a publicly available, annually updated synthesis of in situ surface ocean CO2 measurements with quality control for the global ocean. It is widely used for quantification of ocean CO2 uptake and ocean acidification and for evaluation of earth system models and biogeochemical sensors. However, SOCAT lost its European data management hub in 2022. In response the ‘Case for SOCAT as an integral part of the value chain advising UNFCCC on ocean CO2 uptake’ was published in 2023. This was followed by the ‘Declaration on operationalising the Surface Ocean Carbon Value Chain’ in 2024. Delivery of routine global gridded products of air-sea CO2 flux is an ambition of the World Meteorological Organization’s (WMO) Global Greenhouse Gas Watch (G3W) in its draft implementation plan for 2024-2027. To this purpose the G3W highlights the need to formalize and enhance SOCAT, notably by developing its infrastructure, by furthering interoperability with other ocean carbon products, by modernizing its computing infrastructure and by coordination with the MEMENTO (MarinE MethanE and NiTrous Oxide) data base for oceanic CH4 and N2O. Addressing chronic funding shortfalls and enhancing SOCAT to meet the G3W’s ambition will require countries around the world to invest in SOCAT. Here we will celebrate SOCAT, highlight the challenges it is facing and present a vision of SOCAT within G3W.

 

102 Continuous high-frequency CO2, CH4 and N2O fluxes year-round from the boreal Siikaneva Bog, Finland

Oral

Claire Treat1*, Lona van Delden1, Katharina Jentzsch1, Josh Hashemi1, Julia Boike1, Eeva-Stiina Tuittila2

1AWI, Potsdam, Germany. 2University of Eastern Finland, Joensuu, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

We measured CO2, CH4 and N2O fluxes continuously year-round in high-frequency from the Siikaneva (FI) boreal peatland using an automated chamber system in the FluxWIN project, with sites ranging from a wet bog to a boreal forest on mineral soil. The wet bog was a small net sink of CO2 in 2022. For CH4 in particular, our data indicate that the wet bog is emitting up to 30 % of its annual budget during the shoulder seasons and winter, highlighting the important role of the non-growing season for budgets. Additional vegetation removal experiments were used to parse CH4 emissions pathways, production, and oxidation throughout the year. These showed the importance of oxidation in the system and the interactions between temperature, water table, and vegetation. Parts of the peatland around the FluxWIN automated chamber system and the vegetation removal experimental site were classified for their vegetation categories via drone imagery. Together, these results can be used to improve the representation of CH4 fluxes and C cycling throughout the year.

 

103 Anthropogenic CO2, air-sea CO2 fluxes and acidification in the Southern Ocean: results from a time-series analysis at station OISO-KERFIX (51°S-68°E)

Oral

Nicolas Metzl1, Claire Lo Monaco1*, Coraline Leseurre1,2, Céline Ridame1, Gilles Reverdin1, Thi Tuyet Trang Chau3, Frédéric Chevallier3, Marion Gehlen3

1LOCEAN-IPSL, Paris, France. 2now at VLIZ, Oostende, Belgium. 3LSCE-IPSL, Gif-sur-Yvette, France

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

We evaluated the temporal variation of air-sea CO2 fluxes and pH in the Southern Indian Ocean based on both in-situ data collected since 1985 at a fixed station and reconstructions from a neural network model. During austral winter, the fugacity of CO2 (fCO2) in surface waters increased at a rate close or slightly lower than in the atmosphere over 1985-2020, whereas we observed contrasting trends in summer depending on the decade and related to changes in phytoplankton biomass. As a result, the regional air-sea CO2 flux evolved from an annual source to the atmosphere in 1985 (0.8 molC.m-2.yr-1) to a sink in 2020 (-0.5 molC.m-2.yr-1). The annual pH trend in surface waters over 1985-2020 was -0.0165 ±0.0040.decade-1 and was mainly controlled by the accumulation of anthropogenic CO2 estimated from subsurface data at +0.53 ±0.01 µmol.kg-1.yr-1 with a detectable increase in the trend in recent years. However, the summer pH trends were also impacted by natural processes that reduced the acidification rate over the last decade. A projection of future total carbon concentrations for a high emission scenario (SSP5-8.5) indicates that the surface pH in 2100 could decrease to 7.32 during winter, 0.86 lower than the pre-industrial pH and 0.71 lower than the pH observed in 2020. For this scenario, the aragonite under-saturation in surface waters would be reached as soon as 2050 and 20 years later for the stabilization scenario SSP2-4.5, with potential impacts on phytoplankton species and higher trophic levels in the rich ecosystems of the Kerguelen Island area.

 

104 Combining NDVI data and flux measurements to estimate CO2 GPP rate and annual photosynthesis.

Poster

Jón Guðmundsson*, Hlynur Óskarsson, Emmanuel Pierre Pagneux

Agricultural University of Iceland, Borgarbyggð, Iceland

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

By combining chamber CO2 flux measurements and remote NDVI data, we were able to establish regression model for predicting site specific photosynthesis with reasonable accuracy applying photosynthetic active radiation (PAR) as main driving variable and NDVI as proxy for seasonal index on vegetation CO2 uptake at available PAR. The NDVI remote sensed available values for individual site was utilised to establish site specific NDVI values for each Julian day (JD). The site specific NDVI values were connected to measured CO2 uptake flux (photosynthesis (Pho)), arrived at by chamber measurements of net ecosystem exchange (NEE) and ecosystem respiration (Reco). PAR was measured simultaneously with flux measurements. Fitting (eq1) to our Pho data, PAR and NVDI at same JD, returned R2 of 0.83

Eq 1. Function of PAR and NDVI fitted to measured Pho

Pho=(a+ln⁡(PAR) )* e^((-0,5*〖(((NDVI-x_0 ))/b)〗^2 ) )

Arguing that photosynthesis of an area depends mostly on available energy (PAR) and the photosynthetic structures available to utilize the incoming energy, and the available structure represented by NDVI or LAI (leaf area index). Pho response to changes in PAR, keeping other parameters constant including available biomass, generally shows strong linear correlation to ln(PAR). Inclusion of a variable representing available structure logically would be a simple multiplication factor (Two structures do double as much as one). Testing that linear option returned by far weaker R2 (~ 0.5-0.65) than above Gaussian relationship and indicating some other amplifying factors to photosynthesis than NDVI.

 

105 BVOCs fluxes characterization from a Sorghum plantation in a Mediterranean ICOS site: exploring phenology, stresses, source and sink ripartition of the net ecosystem exchange

Poster

Antonio Manco1*, Luca Vitale1, Vincenzo Magliulo1, Paul Di Tommasi1, Daniela Famulari2

1CNR-ISAFOM, Portici, Italy. 2CNR-IBE, Bl, Italy

Session 2. Exchange of reactive gases and aerosols between the land surface and the atmosphere in natural and managed ecosystems

Climate change will affect the growing season and increase the occurrence of extreme stressful events, altering crop phenological phases and biogenic volatile organic compound (BVOC) emissions, especially in the Mediterranean region.
   In turn, VOCs significantly affect atmospheric processes and climate. Understanding VOC exchanges in croplands, which cover a substantial portion of habitable land, is crucial. VOC fluxes result from complex interactions among biotic and abiotic processes in ecosystem components like soil and vegetation. 

We present, at first, continuous BVOC fluxes measurements during a growing season in a Southern European sorghum plantation, in the agro-ecosystem of the IT-BCi ICOS site. The findings revealed that the sorghum plantation emitted oxygenated BVOCs, predominantly methanol and acetaldehyde. Self-Organizing Maps (SOM) analysis demonstrated distinct BVOC flux patterns correlating with sorghum growth stages. Additionally, SOM differentiated stressful events like plant lodging and harvest cutting based on BVOC emissions, with higher acetaldehyde emission characterizing lodged plants.

Afterwards, we tried to discern the contribution from soil and plants to the net ecosystem VOC fluxes, investigating their evolution over the season in response to physiological and environmental factors. Ecosystem-level VOC fluxes were measured employing eddy covariance micrometeorological methods copuled with the PTR-ToF-MS VOCs detection. Moreover, VOCs fluxes were measured also from soil, copuling the PTR-ToF-MS with an adapted automated chamber system, while plant VOC fluxes were sampled using cartidriges with an adapted photosynthesis measuring systems, exploring an intracanopy gradient. This research emphasizes the understanding of the ripartition of the sources and sinks of VOCs among the ecosystem compononents.

 

106 Partitioning soil respiration in grassland on peat under different water table heights.

Poster

Ian Clancy1,2*, Rachael Murphy2, Gary Lanigan2, Matthew Saunders1

1Trinity College Dublin, Dublin, Ireland. 2Teagasc, Johnstown Castle, Wexford, Ireland

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Peatlands cover an estimated 21% of Ireland of which, it is estimated 350,000ha are currently under grassland management (Connolly, 2018). Due to the subsequent drainage to make the soil suitable for grass based agriculture these ecosystems emit an estimated ~8mt CO2 eq yr-1. Understanding the drivers of CO2 and CHdynamics under different water table (WT) levels is key for assessing the mitigation potential for this form of management on organic soils. Total respiration (Rtot) is the principal pathway of carbon (C) loss from an ecosystem to the atmosphere. Rtot is often measured in as one flux using eddy covariance or chamber systems but is comprised of two components, autotrophic (Ra) and heterotrophic respiration (Rh). Soil partitioning experiments are useful tools for separating respiration pathways, providing insight into the contribution of Ra and Rh in Rtot. These experiments can also provide useful data for validating process based models for GHG fluxes. 

This study seeks to understand the differences and trends in Ra and Rh under different treatment types using root exclusion under different water table heights on a site in the Irish Midlands. The site has been actively rewetted due to partial drain blocking however, due to differences in elevation and peat depth the site has a variable water table across a small spatial scale. This study uses combination of automated chamber systems and weekly/biweekly smart chamber measurements (CO2 and CH4), coupled with ancillary measurements to quantify the contributions of Ra and Rh to Rtot under different water table heights. 

 

107 Investigation of the Suess effect in the high latitude over the last two decades – A model-data study

Oral

Coraline Leseurre1,2*, Claire Waelbroeck2, Pearse Buchanan3, Gilles Reverdin2, Nicolas Metzl2, Claire Lo Monaco2, Virginie Racapé4, Catherine Pierre2, Jérôme Demange2, Jonathan Fin2

1Flanders Marine Institute, VLIZ, Ostende, Belgium. 2LOCEAN - IPSL, Paris, France. 3CSIRO, Hobart, Australia. 4Pokapok, Plouzané, France

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Anthropogenic CO2 emissions from fossil fuel combustion have caused an increase in oceanic DIC and a decline in δ13CDIC (called the Suess effect). δ13CDIC is thus a useful tracer to assess the oceanic uptake of anthropogenic CO2.

Global carbon budgets have revealed a growing deviation over the last 10 to 15 years between the estimates of the ocean carbon sink based on observations and models, with the growth of the observation-based ocean CO2 sink being larger compared to the model estimates (e.g. Friedlingstein et al., 2023). Discrepancies in the multi-decadal trend originate from all latitudes but are greatest in the Southern Ocean.

To investigate the decadal change of both DIC and δ13CDIC we use a hindcast simulation for 1958-2022 (NEMO-PISCES model) and compare the trends over the last two decades with observations from two French monitoring programs focusing on the high latitudes:

  • surface and water column samples from OISO (Océan Indien Service d&apos;Observation) in the South-West Indian Ocean during summer (1998-2021),
  • surface samples from SURATLANT (SURveillance de l&apos;ATLANTique) in the North Atlantic Subpolar Gyre during summer and winter (2005-2019).

Our analysis reveals some inconsistencies between simulated and observed DIC and δ13CDIC, as well as between other simulated and observed biogeochemical parameters, whereas physical parameters are generally well reproduced by the model. Identifying the cause for this mismatch bears the potential to explain all or part of the divergence between the simulated and observed ocean carbon sink.

 

108 Quantifying methane emissions at European scale with a special focus on Austria using inverse modelling

Poster

Sophie Wittig1*, Anjumol Raju1, Martin Vojta1, Omid Nabavi1, Peter Redl2, Antje Hoheisel2, Marcus Hirtl2, Christine Groot Zwaaftink3, Andreas Stohl1

1Department of Meteorology and Geophysics, University of Vienna, Vienna, Austria. 2Department of Numerical Weather Prediction, GeoSphere Austria, Vienna, Austria. 3Norwegian Institute for Air Research NILU, Kjeller, Norway

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

In recent years, methane (CH4) has attracted increasing scientific attention as the second most abundant anthropogenic greenhouse gas (GHG) in the atmosphere. Due to the high reduction potential and the relatively short atmospheric lifetime of around 9 years, mitigation measures can become effective within a relatively short period of time. However, the current estimates of CH4 fluxes from emission inventories are still subject to uncertainties at both global and regional scale.
   An effort to reduce uncertainties from those bottom-up flux estimates is given by inverse modelling, which provides a robust tool to verify GHG emissions by combining GHG observations as well as atmospheric transport modelling and statistical optimization.
   In this study, we use an inverse modelling approach to estimate CH4 fluxes at European scale for the year 2022. Additionally, we use the European in-situ observation network to explore the feasibility of reducing uncertainties in CH4 fluxes in Austria, a European country with a limited availability of stationary observations. This work is part of the Austrian ASAP18 flagship project “GHG-KIT: Keep it traceable”.
   Hereby, the inverse modelling tool FLEXINVERT is used, which is based on the backward simulations of the Lagrangian particle dispersion model FLEXPART (FLEXible PARTicle). In particular, we investigate to what extent prolonged backward trajectories of 50 to 100 days contribute to better constrain the CH4 fluxes. In an attempt to estimate background concentrations as accurately as possible, we use global CH4 concentration fields obtained with the chemical transport model FLEXPART (CTM).

 

109 Exploring the impacts of glacial meltwater on marine CO2 uptake potential: Insights from Young Sound, NE Greenland

Oral

Henry Henson1*, Mikael Sejr1, Isolde Puts1, Lise Lotte Sørensen2, Mie Winding3, Johnna Holding1

1Aarhus University, Aarhus, Denmark. 2Aarhus University, Roskilde, Denmark. 3Greenland Institute of Natural Resources, Nuuk, Greenland

Session 7. Carbon Cycling along the Land Ocean Aquatic Continuum

The global oceans mitigate climate change by sequestering approximately 25% of annually emitted anthropogenic carbon dioxide (CO2). High latitude shelf waters, such as Greenlandic fjords, represent important sinks for CO2 due to their distinct environmental conditions. However, global surface warming is accelerating the retreat of the Greenland ice sheet and meltwater discharge into fjord waters. This freshening of fjord ecosystems induces biogeochemical changes that impact the carbonate system and alter fjord circulation dynamics, potentially influencing future productivity and rates of CO2 uptake. The pronounced freshwater gradients that are formed between the Greenland ice sheet and shelf waters provide useful insight into carbon cycling in a future, fresher Arctic. High resolution sampling of Young Sound, NE Greenland combined with controlled seawater-freshwater mixing experiments, sheds light on the varying effects of glacial meltwater on the marine carbon dynamics driving air-sea exchange. This multifaceted approach allows us to examine the relative physical, chemical, and biological impacts of freshwater in this ecosystem. Long term observations by the Greenland Ecosystem Monitoring (GEM) Program at the same location serve as an environmental barometer, gauging climate impacts and ecosystem shifts in the Arctic. Our dataset of pCO2, now rounding 1.5 decades, helps to illustrate the evolution of fjord waters as a carbon sink and explain processes of freshening and modified air-sea exchange in a future Arctic. 

 

110 Quantifying uncertainties in the chamber method for measuring long-term fluxes and treatment effects: statistical issues and reproducibility

Poster

Peter Levy*, Nick Cowan

Centre for Ecology and Hydrology, EDINBURGH, United Kingdom

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Fluxes of greenhouse gases are typically very heterogeneous in space and time, particularly in the case of N2O. Often we are interested in emission factors, which involves estimating the cumulative flux over a number of months. Estimating emission factors from a small sample of heterogeneous data, and propagating the uncertainties correctly is difficult. Because of this, studies which set out to examine effects of experimental treatments on fluxes and emission factors often under-estimate their statistical power (the probability of detecting an effect when it is present) and the biases from spatial heterogeneity. This results in a high false discovery rate (the probability of a p value < 0.05 being a false positive) in such experiments. High false discovery rates are one of the root causes of the reproducibility crisis, which is widely acknowledged in social and biomedical science, but less well recognised in ecology and biogeosciences. The upshot is that many published results are false, and many valid studies with less clear-cut results go unpublished. Here, we examine the extent of this problem in the domain of chamber fluxes of GHGs, focussing on N2O. We look at the causes in terms of the uncertainties introduced by the flux measurement process, spatial upscaling, extrapolating in time. We analyse the advantages and disadvantages of automated chamber systems versus manual chamber (higher temporal coverage versus higher spatial coverage). Lastly, we make some recommendations for experimental design, and necessary sample size, and recommend a Bayesian approach, which circumvents the problem by avoiding null-hypothesis testing.

 

111 Temporary soil waterlogging affects CO2 flux dynamics but not the cumulative emissions

Poster

Reija Heinonen1,2*, Sanna Kanerva1, Markku Koskinen1,2, Tatu Polvinen1,2, Jussi Heinonsalo1,2, Mari Pihlatie1,2

1University of Helsinki, Helsinki, Finland. 2Institute for Atmosphere and Earth System Research, Helsinki, Finland

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Increasingly variable rainfall patterns and mild winters may result in more frequent and prolonged off-season waterlogging in northern latitudes. Yet, until recently the effect of periodic anoxic conditions on carbon dioxide (CO2) production has been overlooked in mineral upland soils increasing uncertainties in modelled CO2 fluxes. A monolithic soil lysimeter experiment with 32 intact monoliths (l=63 cm, d=15.2 cm) from two agricultural fields (silty clay, sandy loam) in southern Finland was used to study the effect of off-season waterlogging on soil CO2 production. During the 1.5-year study, half of the monoliths were subjected to three waterlogging episodes (48-54 days) outside the growing seasons, while the rest were maintained at 50% water filled pore space. Soil temperature, moisture and redox potential were continuously measured, and dissolved organic (DOC) and inorganic carbon (DIC) concentrations in pore water were analyzed at three soil depths (10, 30 & 50 cm). CO2 fluxes were measured with a manual chamber. Waterlogging reduced CO2 fluxes during saturation but increased the DIC in soil pore water indicating an accumulation of CO2 in the soil. Thus, the reduced CO2 fluxes were not only due to reduced respiration but also to hindered diffusion and release of CO2 from water saturated soil. Drainage induced a rapid pulse in CO2 fluxes in sandy loam and a more gradually increased CO2 release in s  lowly drying silty clay. The increase in CO2 fluxes after drainage roughly equaled that of the decrease during saturation and hence, waterlogging did not significantly alter cumulative COemissions. 

 

112 Conversion or Conservation: Significance of Forest and Heathland Ecosystem in an Ecological Balance. 

Poster

Mahum Naseer*, Matteo Campioli, Marilyn Roland, Fran Lauriks, Ivan Janssens

Universiteit Antwerpen, Antwerp, Belgium

Session 13. In situ data for climate and other environmental services and policy support

Conversion of forest into heathland is increasingly being considered as a new paradigm for heathland ecosystem restoration among scientists and policy makers. However, the potential of temperate heathlands in Western Europe for climate mitigation has little been studied and should be evaluated through continuous monitoring of greenhouse gas (GHG) emissions using the eddy covariance method. In order to assess the impact of ecosystem conversion, analysis of the intricate carbon and water dynamics of both ecosystems is imperative. Carbon and water fluxes provide insight into ecosystem services such as carbon sequestration, climate and water regulation. In addition, water exchange and storage determines the ecosystem resilience to climatic extremes. This study, aiming at analyzing carbon and water fluxes of forest and heathland, is  carried out at two of ICOS ecosystem stations:  "Maasmechelen" is a dry heathland and "Brasschaat"  is a Scots pine dominated forest. Both are located in Flanders, Belgium. The  results of the study demonstrate the potential of both ecosystem for enhancing productivity and mitigating atmospheric CO2 emissions in a global change scenario. This study therefore provides an evidence based approach in examining the trade-offs and benefits associated with ecosystem conversion,  and can assist in determining effective management strategies. 

 

113 Carbon sinks in prodeltaic sediments : a double-trigger environment

Oral

Eva Ferreira1, Christophe Rabouille1, Bruno Lansard1, Jens Rassmann1, Bruno Bombled1, Jean-Pascal Dumoulin2, Eric Viollier1

1LSCE-UMR 8212-CEA-CNRS-UVSQ, CEALSCE-UMR 8212-CEA-CNRS-UVSQ, Gif-sur-Yvette, France. 2LMC14-LSCE-IPSL-CEA-CNRS-UVSQ, Gif-sur-Yvette, France

Session 7. Carbon Cycling along the Land Ocean Aquatic Continuum

Coastal benthic ecosystems with high sedimentation rates have been known for hosting large sinks of carbon through the burial of organic matter. In river-dominated ocean margins (RiOMar), the origin of the buried organic matter is dominated by terrestrial debris in marine environments, highlighting the linkage between continents and oceans, the two major reservoirs at the Earth surface. Consequently, river deltas represent a prominent carbon sink in the world ocean: despite its 0.3% of the surface area, it represents 40% of organic carbon burial in the entire ocean sediments. A new approach, based on differential bathymetry, will be presented for calculating the carbon balance in the Rhône River prodelta.

Conversely, prodeltaic sediments are very active organic carbon recycling zones which give rise to the double-trigger carbon sink. These organic-rich sediments undergo intense anoxic diagenesis producing substantial amounts of total alkalinity (TA). In aquatic systems, changes in alkalinity can generate sinks of CO2 originating from the atmosphere or can limit the efflux of dissolved inorganic carbon (DIC) associated with organic matter mineralization. High-accumulation sediments have the potential to sequester reduced products from anoxic diagenesis, such as FeS, in deep layers leading to the generation of TA fluxes to the coastal bottom waters. In this presentation, the theoretical framework relating TAfluxes to the anoxic processes will be emphasized together with an example in the Rhône prodelta sediments. The DIC/TA ratio amounting from 0.5 to 1 greatly limit the acidification potential of the released DIC without creating an additional sink for atmospheric CO2.

 

114 Enhancing Constraints on Atmospheric Nuclear 14CO2 Contributions in Europe to Improve Continental 14CO2-based Fossil Fuel Estimates

Poster

Timo Knaack1*, Ute Karstens2,3, Zhendong Wu2,3, Samuel Hammer4

1Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany. 2ICOS Carbon Portal at Lund University, Department of Physical Geography and Ecosystem Sciences, Lund, Sweden. 3ICOS ERIC, Carbon Portal, Lund, Sweden. 4ICOS CRL, Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Since fossil fuels lack radiocarbon (14C), the dilution of the 14C/C ratio in atmospheric CO2 can be used to estimate recently added fossil fuel CO2 (ffCO2). However, variations in this ratio are also caused by 14CO2 discharges from nuclear power plants and nuclear fuel reprocessing facilities, which may mask a significant share of the ffCO2 signal on regional and continental scales. The unavailability of temporally fine-scale 14CO2 discharge data from the nuclear facilities increases the uncertainty in 14CO2-based ffCO2 estimates. The European Commission&apos;s Radioactive Discharges Database (RADD) publicly provides data on annual total nuclear 14C discharges for most facilities located in the European Union. For a subset of nuclear power plants,  two-week cumulative 14C discharge observations were provided on a confidential basis from the operators. Here, we explore the possibility of enhancing the RADD discharge time resolution by merging the annual information with publicly available high-resolution electricity output of nuclear power plants, using the knowledge gained from the subset of two-week cumulative 14C discharge observations. In addition to improving the temporal resolution, we compare two approaches to model nuclear 14CO2 contributions at ICOS class 1 sites using either Lagrangian footprint or Gaussian plume modelling. Our ultimate goal is to better assess the uncertainties associated with nuclear contributions and to improve their correction factors in the 14CO2-based fossil fuel estimates.

 

115 Long term flux measurements of carbon dioxide and methane over a small boreal lake using eddy covariance technique

Oral

Ivan Mammarella1*, Joonatan Ala-Könni1, Marta Fregona1, Jouni Heiskanen2, Kukka-Maaria Kohonen3, Asta Laasonen1, Xuefei Li1, Sally MacIntyre4, Anne Ojala5, Aki Vähä1, Timo Vesala1

1Institute for Atmospheric and Earth System Research (INAR) / Physics, University of Helsinki, Helsinki, Finland. 2Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland. 3Department of Environmental Systems Science, ETH Zurich, zurich, Switzerland. 4Earth Research Institute, University of California, Santa Barbara, USA. 5Natural Resources Institute Finland (Luke), Helsinki, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Advancing our understanding on physical and biogeochemical processes controlling turbulent exchange of energy, carbon dioxide (CO2), methane (CH4) and other trace gases across lacustrine systems is crucial in order to improve climate and weather forecast models. Lakes are capable of processing large amounts of organic carbon of terrestrial origin, and their importance in landscape carbon cycle and climate change issues is well recognized. Nevertheless, the amount of CO2 and CH4 released into the atmosphere is still uncertain. 

Here, we investigate the temporal dynamics of CO2 and CH4 exchange using eleven years (for CO2) and three years (for CH4) of eddy covariance flux measurements over the Lake Kuivajärvi, a small boreal lake in southern Finland. 

The lake ecosystem acted mostly as a net CO2 source (0.42±1.56 mmol m-2 s-1) throughout the ice-free periods and had a relatively high interannual variability when compared to the surrounding forests and wetlands. On average, the lake is a net source of CH4 (0.63±2.44 nmol m-2 s-1), but the measured annual emissions are lower than for CO2, revealing that most of the CH4 produced at the lake bottom is oxidized in the water column. Carbon dioxide and methane emissions are largely affected by the weather forcing through the effects of wind shear and nocturnal water cooling, which deepens the mixed layer and enhances gas exchange at the air-water interface.

 

116 Advancements in Detection and Quantification Techniques of Methane Emissions at site level using UAV

Poster

Roubina Papaconstantinou1*, Jean-Daniel Paris2,1, Pierre-Yves Quehe1, Christos Keleshis1, Maria Kezoudi1, Jean Sciare1

1Climate and Atmosphere Research Center (CARE-C), the Cyprus Institute, Nicosia, Cyprus. 2Laboratoire des Sciences du Climat et de l’Environnement (LSCE/IPSL), CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

Methane (CH4) is the second most important anthropogenic greenhouse gas. Reducing CH4 emissions is necessary to mitigate climate change. The potential for CH4 emissions mitigation is strongly linked with improvements on individual sites, be it industrial sites (natural gas), landfills or farms. Therefore, the reliability of tools to identify and monitor emissions at site level is urgent.

Methodologies for methane measurement have evolved over the past two decades, including ground-based, mobile, and remote-sensing techniques utilizing aircraft, unmanned aerial vehicles (UAVs), and satellites. Owing to their ease of mobility, UAVs enable the quantification of point and facility-scale sources, where conventional methods may fall short (Liu et al., AMT 2024). We developed a new UAV-CH4 system exploiting an ABB LGR GLA131 and 3D wind measurements on-board a high-endurance octocopter platform with advanced autopilot capabilities. The "CH4LKIDIQY" campaign conducted in Nicosia in January 2024, aimed to assess the capability of the UAV-based system to detect a CH4 source during controlled-release experiments. The on-board gas analyser successfully detected the tracer gas at low release rates (0.15 kg/h) below a 5-meter height above the emission point.

Our investigation extended to quantifying CH4 emissions from a cattle farm in Orounda, Cyprus, utilizing the same UAV-based system. Data collected mapped in detail the CH4 plume dispersion downwind the farm with concentration variations during multiple flights. These findings significantly contribute to understanding the dispersion of CH4 emissions, improving quantification methodologies. This work will ultimately contribute to inform strategies to reduce site-level methane emissions and mitigate climate change.

 

117 New insights into subsurface pCO2 gradients and flux estimates under extreme conditions enabled by the Waveglider platform

Poster

Dariia Atamanchuk1*, Sean Morgan1, Jannes Koelling2, Clark Richards3, Mark Barry4

1Dalhousie University, Halifax, Canada. 2University of Washington, Seattle, USA. 3Bedford Institute of Oceanography, Halifax, Canada. 4Pro-Oceanus Systems Inc, Bridgewater, Canada

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

The development and evaluation of new fit-for-purpose pCO2 measuring systems capable of performing high-quality measurements is a cornerstone for expanding the number, type and geographical coverage of observations, which contribute to closing the existing observational and knowledge gaps in CO2 fluxes. New measurements reduce uncertainties in models and data products that use machine learning to fill observational gaps (Behncke et al., 2024) and help resolve air-sea fluxes under extreme wind events such as hurricanes and tropical cyclones. 

Conventionally, air-sea CO2 flux is calculated using surface data from the underway systems on ships of opportunity (SOOP), assuming homogeneity in the top 10 m of the water column. This assumption was recently challenged due to biotically and abiotically driven surface gradients (e.g. Watson et al., 2020).  

Through industry-academia collaboration, we integrated CO2 Pro-CV pCO2 sensors into a Waveglider platform. Simultaneous measurements at the surface and a depth of 4m using two cross-calibrated instruments were used to explore the near-surface pCO2 gradient and its variability on the Scotian Shelf over 28 days in the spring of 2022. We also analyzed data from a deployment on the continental shelf south of Nova Scotia during Hurricane Fiona in mid-September 2022, along with complementary measurements from a SeaExplorer glider. The Waveglider carried a suite of sensors measuring temperature, salinity, dissolved oxygen, pCO2, pH, total dissolved gas pressure, wind speed and wave height, and atmospheric pressure, resulting in a uniquely rich data set to analyze air-sea fluxes and the hurricane-induced changes in ocean biogeochemistry. 

 

118 From Science to Service: Leveraging Urban CO2 Monitoring for Actionable Science-based Policymaking - Insights from Paris Case Studies

Oral

Arthur Pécondon-Lacroix1*, Jinghui Lian1,2, Laurent Millair1, Hervé Utard1, Ivonne Albarus1,2, Philippe Ciais2, Olivier Laurent2, Thomas Lauvaux3, Michel Ramonet2, Mali Chariot2, David Duccini1

1Origins.earth, SUEZ Group, Paris La Défense Cedex, France. 2Laboratoire des Sciences du Climat et de l&apos;Environnement (LSCE), IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif sur Yvette Cedex, France. 3Groupe de Spectrométrie Moléculaire et Atmosphérique (GSMA), Université de Reims-Champagne Ardenne, UMR CNRS 7331, Reims, France

Session 12. Translating Scientific CO2 Emission Research into City Services

Transitioning the state-of-the-art monitoring of urban CO2 emissions from a scientific endeavor to a municipal service could offer significant advantages. It not only supports cities to build healthier, more resilient, and sustainable communities but also contributes to the fight against climate change. Currently, cities still face technical challenges to establish an operational capability able to bridge scientific findings and practical implementation. We conducted several case studies in Paris to evaluate how public policies implemented by local authorities affect CO2 emissions. The analyses combine a high-resolution CO2 emissions inventory, various open-source activity data, and atmospheric measurements with urban climate policies. Results show that the Paris Respire initiative, which designates restricted zones to promote soft mobility, led to a reduction in traffic CO2 emissions varying from 39% to 56% across different zones. On car-free days in Paris, traffic CO2 emissions can decrease by up to 25.6%. The Rue de Rivoli Cycle Path led to a 49% reduction in local traffic CO2 emissions when comparing the years 2022 and 2018. Moreover, we investigate how cities can address two key goals: (1) understanding policy impacts across different spatiotemporal scales and (2) continually adapting the territory for science-based policy evaluation. Our findings highlight the importance of recognizing distinct patterns and behaviors as significant indicators for policymakers, urging consideration of both direct and indirect effects over short and long terms. We believe that demonstrating the integration of scientific approaches in Paris could serve as a model, assisting other cities to reach their respective climate objectives.

 

119 Warming and cooling effect based on CO2 fluxes and albedo changes in different N:P ratios in Mediterranean savanna ecosystem

Poster

Bayu Hanggara1,2*, Tarek El-Madany1, Arnaud Carrara3, Stefan Metzger4,5, Anke Hildebrandt2,6, Markus Reichstein1, Sung-Ching Lee1

1Max Planck Institute for Biogeochemistry, Jena, Germany. 2Friedrich-Schiller University, Jena, Germany. 3Fundacion Centro de Estudios Ambientales del Mediterraneo, Valencia, Spain. 4University Winsconsin-Madison, Wisconsin, USA. 5AtmoFacts LLC, Colorado, USA. 6Helmholtz-Centre for Environmental Research - UFZ, Leipzig, Germany

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Changes in both greenhouse gas fluxes and albedo are associated with biogeochemical cycles and biophysical properties that influence net radiative forcing (RF) of terrestrial ecosystems. Ecosystem-atmosphere interactions of semi-arid savanna ecosystems are complicated by the tree-grass coexistence. This study investigates net warming and cooling effects on the surface (local scale) and top of atmosphere (global scale) due to differences in nitrogen (N) and phosphorus (P) ratio changed by fertilisation. We used a long-term dataset (2014-2023) collected at three co-located eddy-covariance sites in a Mediterranean savanna, Spain (i.e., ES_LMa, ES_LM1, and ES_LM2 representing control, N, and N+P added, respectively). Locally, we observed cooler surface temperatures (Tsurf) (across ecosystem, tree, and grass layers) of -0.08 to -0.35 °C at ES_LM1 and warmer Tsurf of -0.09 to 1.43 °C at ES_LM2 compared to control. We calculated differences in net RF between the sites considering changes in both albedo (Δα) and net ecosystem exchange (ΔNEE). The results indicate that both fertilisation treatments increased ecosystem albedo, especially during summer periods (Δα = 0.015 to 0.021) and enhanced ecosystem carbon sink capacity (ΔNEE =-63.12 to -56.17 gCm-2yr-1). Overall, net RF changes due to fertilisation were dominated by Δα, leading to a net cooling effect (-1.04±0.33 and -0.41±0.59 10-14Wm−2(global)m-2, respectively for ES_LM1 and ES_LM2). Therefore, fertilisation treatments in savannas can alter Tsurf and net RF. We aim to further assess which eco-physiological factors contributed to Tsurf dynamics of ecosystem, tree, and grass levels. 

 

120 Volatile organic compounds emission and secondary organic aerosol formation from agricultural recycling of organic waste products

Poster

Raluca Ciuraru1*, Yang Liu1, Céline Decuq1, Baptiste Esnault1, Anais Feron1, Cristian Focsa2, Kawssar Haider2, Florenc*

e Lafouge1, Florent Levavasseur1, Benjamin Loubet1

1INRAE, Université Paris-Saclay, AgroParisTech, UMR ECOSYS, Palaiseau, France. 2Univ. Lille, CNRS, UMR 8523, PhLAM, Lille, France

Session 2. Exchange of reactive gases and aerosols between the land surface and the atmosphere in natural and managed ecosystems

Agriculture with the use of fertilizers is known to emit volatile organic compounds (VOC) that have the potential in forming secondary organic aerosols (SOA) through their reactions with atmospheric photo-oxidants. In a societal context that encourages the recycling of Organic Waste Products (OWP) in agriculture, the comparative effects of mineral fertilizers and OWP on these emissions are of particular interest. The objective of this project is to elucidate the mechanisms of production and degradation of VOC emitted by different OWP and to quantify the potential for SOA formation. It addresses this fundamental problem in atmospheric science by combining laboratory experiments and field measurements. It also aims to model this SOA formation in order to assess the environmental impacts in an agricultural landscape and provide recommendations to preserve air quality following the use of organic and mineral fertilizers.

 

121 Lessons for coastal ocean alkalinity enhancement in a fully-coupled Earth system model

Oral

Andrew Yool1*, Julien Palmieri1, Spencer Liddicoat2, Andy Wiltshire2

1National Oceanography Centre, Southampton, United Kingdom. 2Met Office, Exeter, United Kingdom

Session 8. Enhancing the ocean carbon sink: the science, verification, and governance of marine-based carbon dioxide removal (mCDR)

Reducing carbon dioxide (CO2) emissions from certain activity sectors will be challenging, and carbon dioxide removal (CDR) interventions will be needed to achieve “net-zero” before the end of the 21st century. One of these, ocean alkalinity enhancement (OAE), proposes dissolving basic minerals into the ocean to act as a source of total alkalinity (TA) and to permanently increase its buffering capacity for CO2. However, the slow dissolution of these minerals risks them sinking away from contact with the atmosphere and reducing the efficiency of OAE. To counter this, coastal OAE retains the TA produced near the surface using the shallow seafloor of the ocean’s readily-accessible continental shelves. Here, we investigate this using a state-of-the-art Earth system model, UKESM1, configured to add TA at the temperature-dependent dissolution rate of olivine. Evaluation across the 21st century quantifies ocean CO2 uptake driven by OAE, its redistribution within the ocean, and the general efficiency rate relative to the TA added. The fraction of the CO2 uptake that occurs in the OAE operation area, and the wider balance of the Earth system’s carbon cycle and climate are also examined.

 

122 Estimation of Terrestrial Vegetation Gross Primary Productivity (GPP) using the Quantum Yield Model and Sentinel-3 Data: The QY GPP Product.

Poster

Booker Ogutu1*, Jadu Dash1, Sven Berendsen1, Finn James1, Claire Miller2, Daria Andrievskaia2, Mahmoud El Hajj2, Stephen Plummer3

1University of Southampton, Southampton, United Kingdom. 2NOVELTIS, Labège, France. 3European Space Agency, Frascati, Italy

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Gross primary productivity (GPP), the amount of carbon dioxide (CO2) fixed by plants through photosynthesis per unit area per unit time, plays a critical role in reducing the rate of build-up of anthropogenic carbon emissions in the atmosphere. However, accurate estimation of GPP is still a challenge due to its high spatial and temporal variability. The increasing availability of satellite data offers an opportunity to develop new methods and products to quantify GPP across the globe. Here we present a new global GPP product generated using the Quantum Yield (QY) model and Sentinel-3 data. The QY model is unique in its use of photosynthetic pathway (C3/C4) quantum yield terms to quantify the rate at which plants convert absorbed energy into dry matter. Evaluation of the new QY-GPP product across various biomes, using eddy covariance flux tower data from ICOS and Ameriflux networks, showed that it corresponds well with in-situ data(i.e.,R2= 0.72; RMSE=3.16gCm-2day-1; MAE=2.5 gCm-2day-1 and Bias =1.39; n=2350). Additionally, when compared with two operational satellite-based GPP products (i.e., Copernicus Global Land Service Gross Dry Matter Productivity-CGLS GDMP and MOD17 GPP), the GPP predictions from the QY model explained a higher variability of in-situ measurements (i.e., QY GPP: R2= 0.72; CGLS GDMP GPP: R2 = 0.62 and MOD17 GPP: R2= 0.56). With the expected availability of Sentinel 3 data into the next decades, the QY GPP product offers a new source of data that can be used to characterise GPP and its dynamics across the globe.

 

123 Carbon Balance and Flux Dynamics at the FR-Grignon ICOS Site: A 2005-2023 Analysis

Oral

Carmen Kalalian1*, Pauline Buysse1,2, Jérémie Depuydt1, Anaïs Feron1, Alain Fortineau1, Nicolas P.A. Saby3, Bruna Winck1, Florent Levavasseur1, Pedro Herig-Coimbra1, Benjamin Loubet1

1UMR EcoSys, Université Paris-Saclay, INRAE, AgroParisTech, 91120 Palaiseau, France

2UMR SAS, INRAE-Institut Agro, 35000 Rennes, France

3UMR Info&Sols, INRAE, Orléans, France

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

As climate change urgency escalates, recognising the role of agricultural lands in carbon management for mitigation strategies becomes crucial. This 18-year study at the Grignon site, a labelled site within the Integrated Carbon Observation System (ICOS) network, located 40 km west of Paris, France, provides a comprehensive analysis of carbon flux dynamics affected by crop rotations and agricultural practices. Utilising the eddy covariance method, we measured net ecosystem exchange (NEE) and evaluated gross primary production (GPP), and ecosystem respiration (Reco). We compiled imported and exported carbon as organic fertiliser and harvest and evaluated carbon loss by leaching, to assess the carbon balance at the Grignon agricultural site, which can be compared to the carbon stock change measured between 2005 and 2019 and the soil carbon balance model AMG.

Our investigation focused on harmonising heterogeneous data over time, encompassing the evolution of methodologies, analysers, and data sources (farmer-reported vs. biomass measurements). This revealed a shift towards the site becoming a carbon emitter, with notable inter-annual variability mainly driven by carbon import and export dynamics. We compared different methodologies for gap-filling and consolidating the imports and exports data using the available information (farmer, biomass sampling). The spatial inhomogeneity of the biomass production in the field was also investigated using high-resolution remote sensing. 

This study underlines the importance of sustainable farming practices for enhancing carbon sequestration and reducing emissions. Such practices are essential for informing policy and promoting climate-resilient agricultural strategies, highlighting informed, sustainable farming&apos;s role in combating climate change.

 

124 Partitioning photosynthesis limitations of potato during edaphic water stress

Poster

Quentin Beauclaire*, Bernard Heinesch, Florian Vanden Brande, Bernard Longdoz

BIODYNE Biosystems Dynamics and Exchanges, TERRA Teaching and Research Center, Gembloux Agro-Bio Tech, University of Liege, Liege, Belgium

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Identifying the physiological processes that limit gross primary production (GPP) of crops during water stress is crucial for ensuring food security. However, the influence of soil water availability on GPP limitation is still not fully understood. We combined gas exchange and fluorescence measurements at the ecosystem scale (eddy covariance) and leaf scale to investigate the origins of photosynthesis limitations of potato (Solanum Tuberosum) under soil water availability-limiting conditions in central Belgium. We aimed to determine whether GPP limitations originated from stomatal (decrease in the stomatal sensitivity to photosynthesis g1) or non-stomatal factors (decrease in the maximum carboxylation rate Vcmax or in the mesophyll conductance gm). The analysis of eddy covariance data of four consecutive growing seasons of potato at the Lonzée ICOS station (BE-Lon) shows a consistent effect of non-stomatal factors on GPP. Non-stomatal factors can be partition between gm or Vcmax when joint gas exchange and chlorophyll fluorescence measurements are performed. To that end, we set up a drought experiment and measured the response of gas exchange and chlorophyll fluorescence at the leaf level to the decrease in REW. Stomatal and mesophyll conductance were the first factors to be reduced while Vcmax decreased from a lower REW threshold. Limitation analysis showed that gm accounted for most of the decrease in stomatal conductance and photosynthesis. We emphasize the need to consider the effects of drought on mesophyll conductance to reduce uncertainties when modeling photosynthesis and transpiration of potato. Revisiting the partitioning methods to fully unravel the physiological controls on carbon and water fluxes during water stress is needed.

 

125 Continuous in-situ measurements of atmospheric CH4 at an urban-industrial station: a two-year analysis of CH4 spatio-temporal variability and sources identification using co-emitted species

Poster

Pauline Bosio1*, Irène XUEREF-REMY1, Pierre-Éric Blanc2, Aurélie Riandet3, Grégory Gille4, Alexandre Armengaud4, Sonia Oppo4

1IMBE, Aix Marseille Univ, Avignon Univ, CNRS, IRD, Aix-en-Provence, France. 2UAR Pythéas, CNRS, Observatoire de Haute Provence, Saint-Michel l’Observatoire, France. 3Université de Toulouse, CNRS, CNRM, Météo France, Toulouse, France. 4ATMOSUD, Marseille, France

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Methane (CH4) is the second most important direct anthropogenic greenhouse gas, with a lifetime about 10 times shorter than carbon dioxide (CO2) and a warming potential 80 times greater over a 20-year period. Reducing CH4 emissions therefore represents a lever for rapid action on global warming. The Sud-PACA region (south-eastern France), classified by IPCC as a climate "hotspot", is part of these efforts to reduce CH4 emissions, with the aim of achieving carbon neutrality by 2050. To reach this goal, reducing uncertainties of regional CH4 emissions is therefore essential. Over 50% of Sud-PACA methane sources are estimated by the ATMOSUD regional inventory (https://cigale.atmosud.org/) to be located in the southwestern part of the region. This area is highly urbanized and industrialized as it comprises France’s second-largest industrial zone. However, the ATMOSUD inventory has never been assessed independently. To fill this gap and to better characterize anthropogenic sources of CH4 in this area, a top-down approach was developed, based on a new atmospheric CH4 monitoring station consisting of a Picarro Cavity Ring-Down Spectroscopy analyzer and a meteorological station installed in May 2021 as part of the ANR COol-AMmetropolis project at Port-de-Bouc. We will present the diurnal, synoptic and seasonal variability of atmospheric CH4 at PdB, an analysis of the relationships between CH4, CO and CO2, a source identification study using 13CH4 isotopic signatures and a comparison with the literature. These data represent the first measurements of CH4 in this industrial area and will also be used to independently verify regional inventories.

 

126 Crop gross primary production and yield estimation from Sentinel-2 data using a light use efficiency model

Oral

Rahul Raj*, Bagher Bayat, Carsten Montzka

Institute of Bio- and Geosciences: Agrosphere (IBG-3), Forschungszentrum Jülich, Jülich, Germany

Session 14. Leveraging Direct Flux Measurements Beyond Academia for Real-World Applications

Agricultural fields globally can reduce 10% of greenhouse gas emissions by absorbing COduring photosynthesis (Gross Primary Production: GPP) process. It is indispensable to precisely capture the spatiotemporal dynamics of crop GPP over the field. A remote sensing (RS) based Light Use Efficiency (LUE) model can provide a high-resolution spatiotemporal estimate of crop GPP, which can be further linked to the quality-assured estimate of crop yield. At field scale, the accuracy of LUE model depends on how well the spatiotemporal dynamics of land surface properties such as crop Leaf Area Index (LAI) are captured. In this study, we retrieved 10m resolution LAI from Sentinel-2 satellite data by implementing a hybrid inversion approach that combines radiative transfer model PROSAIL with machine learning. We retrieved LAI during the growing seasons of winter wheat, rapeseed, and barley from 2016 to 2019 at the ICOS agriculture field in Oensingen, Switzerland. The retrieved LAI were further fed into the LUE model to simulate GPP at 10 m resolution. The statistical relationship between simulated GPP and flux tower GPP demonstrated by Kling-Gupta efficiency (KGE) indicated the reasonable accuracy of the LUE model. The simulated GPP over the growing period of each crop was further converted into crop yield by utilizing crop-specific harvest index, moisture content, and root-to-aboveground biomass ratio. The percentage difference between the measured and estimated yield varied from 2% to 20%. Our results demonstrated that LUE is an essential class of RS data-driven model for estimating GPP and crop yield to address food security.

 

127 Evaluating GHGSat total column methane measurements using nested WRF LES simulations

Oral

Yunsong Liu1*, Ying Pan1, Nikolay V. Balashov2,3, Zachary Barkley1, Kenneth J. Davis1,4

1Department of Meteorology and Atmospheric Science, The Pennsylvania State University, University Park, PA, USA. 2Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD, USA. 3Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, MD, USA. 4Earth and Environmental Systems Institute, The Pennsylvania State University, University Park, PA, USA

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Methane (CH4) is an efficient target for rapid climate change mitigation due to its stronger radiative forcing compared to carbon dioxide (CO2). To better understand anthropogenic CH4 emissions sources, high spatial resolution satellite instruments were launched by GHGSat during recent years to measure methane emitted from relatively large point and area sources. The objective of this study is to test the performance of GHGSat’s measurements of CH4 plumes at a landfill in Indianapolis, Indiana, which is a well-studied CH4 emission source. GHGSat total column CH4 measurements are evaluated against plumes simulated using the Weather Research and Forecasting (WRF) model nested from mesoscale to large-eddy simulation (LES) domains. A total of six one-way nested domains are used to simulate dispersion of tracers in the turbulent atmospheric boundary layer with realistic mesoscale forcing. The 37 m horizontal grid spacing of the inner most domain is comparable to the 30 m spatial resolution of GHGSat. With landfill emissions represented as a constant, continuous source of tracers, dispersion results in the inner most domain are compared to GHGSat observed CH4 plumes. The analyses performed for a total of ten different days show considerable day-to-day variation and can be grouped roughly as: 1) excellent agreement in plume location and concentration; 2) plumes of similar concentrations but dislocated; and 3) plumes not observed by GHGSat. The causes for these discrepancies will be investigated using available observations of mean and turbulent winds and eddy-covariance measurements of CH4 fluxes. 

 

128 Towards a pan-African Research Infrastructure for Atmospheric, Climate and Ecosystem Services: Three Decades of International Collaboration in Kenya

Oral

L. Bernet1*, B. Brem2, L. Emmenegger1, C. Félix3, J. Kimutai4, L. Merbold5, M. Mutuku4, D. Njiru4, S. Nyandida4, P. Nying’uro4, V. Odongo6, P. Pellikka7, M. Steinbacher1, K. Thiong’o4, J. Klausen3

1Empa, Laboratory for Air Pollution / Environmental Technology, Dübendorf, Switzerland. 2Paul Scherer Institute PSI, Villigen, Switzerland. 3Federal Office of Meteorology and Climatology MeteoSwiss, Zurich, Switzerland. 4Kenya Meteorological Department, Nairobi, Kenya. 5Agroscope, Zurich, Switzerland. 6International Livestock Research Institute ILRI, Nairobi, Kenya. 7University of Helsinki, Helsinki, Finland

Session 13. In situ data for climate and other environmental services and policy support

Consistent, reliable and long-term data – documenting variability and trends of atmospheric composition and land-atmosphere interactions – are needed across the globe to address climate change and health. Large regions remain undersampled. This is especially true for Africa, which already experiences the impacts of climate change at a large scale. Under the auspices of the WMO GAW and GCOS Programmes and NASA’s SHADOZ project, Switzerland has collaborated with the Kenyan Meteorological Department (KMD) since 1996 to support atmospheric observations in Kenya. This has resulted in regular ozone soundings in Nairobi and continuous observations of gases and aerosols at the Global Atmosphere Watch (GAW) station Mount Kenya. Furthermore, several eddy-covariance flux towers were installed to observe the net exchange of CO2, CH4 and water vapour from diverse ecosystems in Kenya. More recently, the Horizon Europe project KADI (Knowledge and climate services from an African observation and Data research Infrastructure) has provided a pan-African context to these activities to connect distributed and sparse activities into an integrated research infrastructure. Quality control, hardware acquisition, training, and data analysis are key elements of the collaboration.  

We will share results obtained and experience gained during the long-lasting partnership and provide lessons learned. This is critical information paving the way towards designing comprehensive monitoring and research capabilities for climate change observations, as well as the provision of climate and air quality information and services across Africa.

 

129 How reliable are process-based radon flux maps? Results from a radon inversion in Europe

Poster

Fabian Maier1*, Ute Karstens2, Eva Falge3, Maksym Gachkivskyi4, Ingeborg Levin4, Christian Rödenbeck1, Christoph Gerbig1

1Max Planck Institute for Biogeochemistry, Jena, Germany. 2ICOS Carbon Portal, Lund University, Lund, Sweden. 3Deutscher Wetterdienst, Zentrum für Agrarmeteorologische Forschung, Braunschweig, Germany. 4Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Inverse modeling provides a powerful tool to estimate and verify greenhouse gas emissions on regional to global scales using independent atmospheric observations. However, its success strongly relies on a proper description of atmospheric transport and mixing processes. In fact, atmospheric transport modeling is responsible for the largest uncertainties of this method, which are also difficult to quantify. Therefore, usually only the observations during well-mixed atmospheric conditions (e.g., in the afternoon), that are well represented in the model, are used to constrain the emissions. 

The radioactive noble gas radon (half-life of 3.8 days) is mainly released from continental soils and shows a strong vertical gradient in the atmosphere. It can thus be used as a tracer for atmospheric mixing. The comparison between modelled and measured radon activity concentrations could therefore pave the way to a more reliable quantification of transport model uncertainties and to the exploration of non-afternoon observations with inverse models. However, this relies on well-calibrated radon measurements and accurate radon fluxes. 

In this study we aim to evaluate the accuracy of process-based radon flux maps for Europe. Their reliability depends on the accuracy of the underlying soil moisture products. We performed a radon inversion to validate these a-priori radon fluxes. We show that our radon inversion yields robust flux estimates for Central Europe, which are mainly data driven but have a higher variability than the process-based fluxes. These results could be used to improve the description of radon exhalation from the soil and thus the radon flux maps themselves. 

 

130 Low-cost sensors for spatially distributed CO2 measurements through Arctic snowpacks

Oral

Victoria Dutch1,2*, Nick Rutter2, Paul Mann2, Alex Mavrovic3, Alexandre Roy3

1University of East Anglia, Norwich, United Kingdom. 2Northumbria University, Newcastle, United Kingdom. 3Université du Québec à Trois-Rivières, Trois-Rivières, Canada

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

Although historically considered negligible, wintertime CO2 emissions from the Arctic tundra are now thought to make up a notable proportion of the annual carbon budget. However, poor availability of wintertime measurements, largely due to logistical and methodological measurement constraints limit our capacity to estimate the magnitude and variability of CO2 emissions. Here we present COmeasurements from new experimental low-cost sensors alongside in-situ profiles of CO2 concentrations and isotope ratios to better account for temporal and spatial variability in CO2 flux at Trail Valley Creek, NWT, Canada during late winter of 2021-2022 and 2022-2023. The experimental low-cost sensors provide very high (sub-minute) resolution timeseries of CO2 concentrations, which we use to derive fluxes for different land cover types. CO2 fluxes measured using both the experimental low-cost sensors and established labour-intensive gas profiling technique show similar magnitudes of CO2 emission. We find spatial variability in land cover and snow depth to impact CO2 fluxes. Across all sites, we typically find concentrations of CO2 at the base of the snowpack greater than atmospheric concentrations, indicative of CO2 emission from frozen soil. More negative carbon isotope ratios are typically found at the base of the snowpack, indicating soil respiration as a source of CO2 at the base of the snowpack. This CO2 emission relates to gas temperatures in a manner consistent with studies which have compiled data from across the Pan-Arctic using a variety of measurement techniques, showing potential for the further development and deployment of these sensors.    

 

131 Grazing vs Silage Cuts: A comparison of the carbon and net greenhouse gas balance of an intensively managed grassland at the field scale.

Poster

Rachael Murphy*

Teagasc, Johnstown, Ireland. Teagasc Climate Centre, Johnstown, Ireland

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

In 2019 and 2020, we assessed the field scale net carbon and greenhouse gas balance (NGHGB) of an intensively managed temperate grassland that is part of the National Agricultural Soil Carbon Observatory (NASCO) – a network of 28 eddy covariance (EC) sites measuring GHGs over different land-uses, managements and soil types. In 2019 the field site was under a cut management for silage production and in 2020 the field site was strip-grazed. Imports and exports were quantified through management data and EC measurements of ecosystem-scale CO2 and N2O fluxes. Literature values were used to estimate C imports and exports, and enteric CH4 fluxes where measurements were not available. The EC measured net ecosystem exchange of CO2 showed that the field site was a sink of C under both managements. Greater C returns were observed under the grazing system through excreta deposition compared to the silage cut system which didn’t receive organic fertilization. Large C exports from biomass removals were measured from both systems.  N2O emissions were higher under the grazing system compared to the cut system, and estimated CH4 emissions from enteric fermentation were circa twice as large as N2O emissions measured during grazing. In both years the net C sink of the grassland (g CO2eq m-2 yr-1) was not significantly different from zero, yielding a NGHGB of -82 ± 574 and 88 ± 507 for the cut and grazing management respectively. NASCO is funded by the Department of Agriculture Food and Marine, the Dairy Levy Trust and co-funded by Terrain-AI.

 

132 Blue Boat: A Low-cost Autonomous Surface Vehicle for Measuring Carbonate System Parameters in Surface Waters

Oral

Sean Morgan1*, Dariia Atamanchuk1, Aaron MacNeill1, Carl Miller1, Mark Barry2

1Dalhousie University, HALIFAX, Canada. 2Pro-Oceanus, Bridgewater, Canada

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

High spatiotemporal resolution carbonate system measurements are crucial for informing models for accurate estimations of air-sea CO2 fluxes and representation of biogeochemical processes  (Resplandy, 2024). Shelf regions and coastal areas are disproportionate in their impact on global CO2 dynamics (Fennel, 2019) and require increased measurement coverage to sufficiently resolve their variable fluxes. 

High frequency monitoring in coastal areas is conventionally accomplished using fixed moorings and buoys outfitted with a suite of sensors. However, the fixed locations of these systems severely limit measurements in the spatial plane. Furthermore, accessibility and rapid turnaround of the sensors is always not possible without ship access.  Compact, autonomous surface vehicles (ASVs) provide easy-access platforms for in-situ sensors and increased deployment flexibility. 

In this study, we present the customization and deployment of the Blue Boat from Blue Robotics: a low-cost autonomous surface vehicle that was outfitted with a suite of sensors for carbonate system parameters: pH, temperature, conductivity, and the partial pressure of CO2 (pCO2). The boat was deployed in the Bedford Basin/Halifax Harbour to investigate variability of pCO2 in surface waters before and during the dosing phase of a local ocean alkalinity enhancement (OAE) trial. The Basin offers an ideal testing ground due to its dynamic hydrographic and biogeochemical conditions and the ongoing OAE trial.

The selection of sensors provided a unique data-set for understanding surface carbon variability, and revealed significant spatial pCO2 gradients , thereby highlighting the importance and potential of vehicle-based, high-resolution monitoring.

 

133 Understanding Ozone Dynamics in Periurban Mediterranean Forests: Insights from Multiannual Flux Measurements

Poster

Roberto Corsanici1*, Tiziano Sorgi2, Adriano Conte3, Silvano Fares4

1Department for innovation in biological, agro-food and forest systems , University of Tuscia, 01100 Viterbo, Italy, Viterbo, Italy. 2Council for Agricultural Research and Economics (CREA), Research Centre for Foresty and Wood, 00166 Rome, Italy, Rome, Italy. 3National Research Council of Italy-Institute of Sustainable Plant Protection (CNR-IPSP), 50019 Firenze, Italy, Metaponto, Italy. 4National Research Council of Italy-Institute for Agriculture and Forestry Systems in the Mediterranean (CNR-ISAFOM), Naples, Italy, Napoli, Italy

Session 2. Exchange of reactive gases and aerosols between the land surface and the atmosphere in natural and managed ecosystems

Tropospheric ozone (O3) is harmful to plants, causing leaf damage, reduced photosynthesis rates, and inhibited growth. Urban areas, abundant with anthropogenic Oprecursors, significantly contribute to Oformation, posing a particular risk to periurban Mediterranean forests. This risk is especially exacerbated by the elevated temperatures typical of Mediterranean regions. Multiannual measurements of ozone (O3) fluxes have been conducted from 2012 to the present in the Oak Holm Forest of Castelporziano Estate, a coastal forest located 25 km from downtown Rome, Italy, class 1 ICOS site. These measurements were carried out utilizing the eddy covariance technique on a 21-meter-high tower. Ozone (O3) fluxes were separated into stomatal and non-stomatal components using the evaporative/resistive method, and Eddy Covariance water fluxes. Utilizing this extensive dataset of ozone fluxes, the current study aims to identify seasonal patterns in ozone stomatal fluxes while addressing the factors influencing their fluctuations. It will also consider the year-to-year variability of ozone fluxes based on climatic conditions, alongside the variability of ozone detoxification efficiency, expressed as the ratio between ozone stomatal flux and carbon dioxide flux, on an annual basis. This work benefits from long-term flux measurements and ancillary measurements performed in the frame of ICOS Italy network.

 

134 Snow as an insurance: winter snowpack protects alpine grassland from early summer drought

Oral

Kukka-Maaria Kohonen*, Yi Wang, Lukas Hörtnagl, Nina Buchmann

Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Grasslands cover up to 70% of the agricultural area in Switzerland, including many (sub)alpine elevations. Over the past decades, snow cover in the Alps has been decreasing due to climate warming. Although diminished snow cover may prompt an earlier growing season start and elevated temperatures could enhance productivity, snowpack significantly impacts grassland water availability, particularly in the early growing season.

In this study, the net ecosystem exchange of CO2 (NEE) was measured with the eddy covariance technique over an extensively managed alpine grassland (2000 m.a.s.l) in Switzerland. The grassland serves as a summer pasture for cattle for approximately three months annually. Data collection spanned nine summers (2006-2014) and nine full years (2015-2023). The grassland acted as a net CO2 sink in all full years, with cumulative NEE varying between -43 and -265 gCm-2. A smaller winter snowpack was linked to earlier snowmelt and growing season onset but also to a decreased net ecosystem CO2 sink. We found that the summertime maximum CO2 sink (minimum daily NEE) partially depends on the amount of snow in the previous winter: the higher the snowpack, the higher the CO2 sink (more negative daily NEE).  In addition, dry atmospheric conditions in the early summer (i.e., June) did not reduce CO2 uptake rate partially due to high winter snowpack. We also observed temporal variations in the importance of radiation, soil moisture and temperature on NEE, with soil moisture being the second most important driver after radiation from the snowmelt period to early growing season (April-June).

 

135 Soil Texture Modulates Ecosystem Water Limitation: From Local to Global Importance of Soil and Atmospheric Drought on Transpiration and Photosynthesis

Oral

Fabian Wankmüller1*, Louis Delval2, Peter Lehmann1, Martin Baur3, Sebastian Wolf1, Dani Or1, Mathieu Javaux2, Andrea Carminati1

1ETH Zurich, Zurich, Switzerland. 2UC Louvain, Louvain-la-Neuve, Belgium. 3University of Cambridge, Cambridge, United Kingdom

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

At a critical soil water content (θcrit), plants downregulate transpiration rate and photosynthesis, shifting terrestrial ecosystems from energy to water limitation and potentially from carbon sink to carbon source. This threshold value θcrit is thus central to assessing soil and atmospheric drought impacts on vegetation and the associated feedback to carbon and hydrological cycle. However, the mechanisms behind θcrit remain poorly quantified, particularly at the ecosystem scale. By applying a soil-plant hydraulic model to tree- and ecosystem-scale observations of θcrit across climates and biomes, we show the global importance of soil-specific hydraulic conductivity for transpiration and photosynthesis. The underlying concept to simulate θcrit assumes that ecosystem water limitation is triggered by a loss in soil or plant hydraulic conductivity. While the relative importance of soil and plant hydraulic conductivity is mechanistically linked to the relative importance of atmospheric and soil drought, these relative importances depend on the soil. Here we find a strong soil texture dependence of θcrit, and more importantly of the corresponding critical soil water potential (ψcrit). In coarse textured soils, ψcrit is small reflecting the steep drop in soil hydraulic conductivity. In these soils, the relative importance of the soil is therefore emphasized compared to fine textured soils, where atmospheric drought and plant hydraulic limitation become comparably more important. Although vegetation-atmosphere exchanges are driven by atmospheric conditions and mediated by plant adjustments, their fate is ultimately soil-dependent. This implies that a widespread increase in atmospheric water demand may exacerbate plant water stress more than previously assumed.

 

136 GEORGE roadmap towards marine data interoperability of 3 ERICs (EMSO – Euro-Argo – ICOS).

Poster

Laurian Van Maldeghem1, Marc Portier1, Katrina Exter1, Thierry Carval2, Aljaz Maslo3, Delphine Dobler4, Claire Gourcuff4, Juan Miguel Villoria5, Ute Schuster6, Thanos Gkritzalis1*

1VLIZ - Flanders Marine Institute, Oostende, Belgium. 2IFREMER, Brest, France. 3EMSO, Rome, Italy. 4Euro-Argo, Brest, France. 5SOCIB, Palma De Mallorca, Spain. 6University of Exeter, Exeter, United Kingdom

Session 17. Best Practices in the landscape of Research Infrastructures: Cooperation, Co-location and other lessons learned

The need to have scientific information, easily available and easy to digest across Research Infrastructures is a necessity rather than a nice-to-have. Development of new technologies and sensors, the complexity of integrated observation systems, and the advances in data science make this a must-have. A working term that describes this is “Interoperability” within the concept of the FAIR principles. Interoperability should not be seen as a Boolean checkbox, nor a gradient scoring the "proximity to completion"; it should be measured in the accumulated "cost of use" of any shared dataset or service: the required effort to tame these various sources leading to new insights. Lowering that cost is the responsibility of the producers of these digital objects declared to be interoperable, and of the community to arrive at sufficient commonalities towards an interoperable "status quo". 

The GEORGE project brings together three Research Infrastructures with a common denominator in ocean observations: EMSO, Euro-Argo, ICOS, covering the European Seas. 

Within GEORGE and following the legacy of projects such as ENVRI-FAIR, we work on how to make our data and services interoperable not just between RIs and to the already-in-the-know, but across RIs and to the don’t-know. The aim is to lower the barriers by achieving interoperability at a machine-to-machine level. This can leverage observations into research and innovative outcomes that support societal needs to comprehend, adapt to, and mitigate global environmental change. The work presented includes tests, findings and recommendations on how to achieve the above. 

 

137 Impacts of warm autumn on carbon sequestration: insights from mature hemiboreal coniferous forest.

Oral

Svyatoslav Rogozin1*, Alisa Krasnova1,2, Ülo Mander1, Veiko Uri3, Kaido Soosaar1

1Institute of Ecology & Earth Sciences, University of Tartu, Tartu, Estonia. 2Swedish University of Agricultural Sciences, Umeå, Estonia. 3Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Tartu, Estonia

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Mature boreal forests play an important role in the global carbon cycle due to their extensive area and ability to sequester a considerable amount of atmospheric carbon dioxide (CO2). They are generally stable ecosystems that function as carbon sinks, however, their sink capacity is vulnerable to the impact of extreme weather conditions. In this study, we aim to investigate the interannual carbon dynamics of a mature coniferous forest (70-230-year-old) located in Estonia in the hemiboreal zone. Over an eight-year period (2016-2023), the forest shifted from a carbon sink (mean net ecosystem productivity (NEP) of 237.76 ± 51.90 g C m−2 year−1) to a carbon-neutral state in 2020 (NEP = −2.13 g C m−2 year−1) and back to a net carbon sink (NEP = 136.18 ± 49.96 g C m−2 year−1). The average NEP over the 8-year period was 169.68 ± 41.99 g C m−2 year−1. The warmest autumn over 19 years recorded in 2020 resulted in noticeably increased ecosystem respiration, which shifted annual NEP towards negative net values, while no significant impact on GEP was found. Our results underscore the importance of continuous monitoring carbon dynamics variability to determine the ecosystem&apos;s resilience to seasonal temperature fluctuations and to inform management strategies for mature forests preservation. 

 

138 Assessment of multiple mid-infrared absorption (MIRA) analyzers’ performance for methane and ethane in the laboratory

Poster

Yunsong Liu1*, Natasha L. Miles1, Scott J. Richardson1, David Miller1, Kenneth J. Davis1,2

1Department of Meteorology and Atmospheric Science, The Pennsylvania State University, University Park, USA. 2Earth and Environmental Systems Institute, The Pennsylvania State University, University Park, USA

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Methane (CH4) is regarded as an efficient target for rapid mitigation of climate change forcing. Ethane (C2H6) to methane mixing ratios can be applied to identify and separate methane sources, specifically in areas with mixed methane sources (e.g. natural gas and biogenic emissions). Aeris Technologies’ MIRA Ultra Leak Detection System (LDS) with continuous in-situ measurements for C2H6 and CH4 has been shown (Commane et al., 2023) to have promising measurement performance and modest size and power requirements. In this study, we tested instrument response to environmental conditions and calibrations in the laboratory to assess three MIRA Ultra gas analyzers’ performance for methane and ethane field measurements. Anticipating use in tower-based deployments requiring high compatibility, we used an external pump in place of the internal pump, dried the air sample, and humidified the calibration gas. We compared results with those of a co-located Picarro G2301. We will describe the precision, bias and drifts found among the instruments, and strategies for controlling instrument performance in the field. 

Reference:

Commane, R., Hallward-Driemeier, A., and Murray, L. T.: Intercomparison of commercial analyzers for atmospheric ethane and methane observations, Atmos. Meas. Tech., 16, 1431–1441, https://doi.org/10.5194/amt-16-1431-2023, 2023.

 

139 Deciphering Arctic Ocean surface ocean carbon fluxes: Insights from Atmospheric Inverse Analyses

Oral

Jayashree Ghosh*, Parvadha Suntharalingam, Zhaohui Chen, Jan Kaiser, Dorothee Bakker, Victoria Dutch

University Of East Anglia, Norwich, United Kingdom

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

The Arctic Ocean contributes significantly to the uptake of oceanic CO2, despite covering only a small fraction (about 4%) of the Earth&apos;s ocean surface (Bates & Mathis, 2009). This study examines the exchange of CO2 between the atmosphere and the Arctic Ocean. We utilize the GEOSChem-LETKF inverse model system (Chen et al., 2021) in conjunction with alternative representations of air-sea CO2 fluxes (prior fluxes) and with atmospheric measurements from the NOAA surface CO2 monitoring network (ObsPack, Cooperative Global Atmospheric Data Integration Project, 2018) to derive optimized surface flux estimates. We assess the sensitivity of our derived flux estimates for ocean and land to different representations of the prior flux distribution and to configuration of the atmospheric observational network. We also present estimates of the long-term trend, year-to-year variations, and regional and seasonal fluctuations in air-sea CO2 exchange in the Arctic Ocean focusing particularly on the area north of 58˚ latitude.  

 

140 Spatial distribution and isotopic signature of methane emissions over the Spanish rural area of the Gredos mountain range.

Poster

Claudia Grossi1*, Roger Curcoll1, David Garcia1, Alba Àgueda1, Lidia Cañas2, Silvia Borràs3, Eusebi Vazquez4, Manel Nofuentes4, Felix R. Vogel5, Josep-Anton Morguí2

1Universitat Politècnica de Catalunya, Barcelona, Spain. 2Universitat de Barcelona, Barcelona, Spain. 3Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain. 4Institut de Ciencies del Clima, Barcelona, Spain. 5Climate Research Division, Environment and Climate Change Canada, Toronto, Canada

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Greenhouse gases emissions must be reported to the United Nations Framework Convention on Climate Change. The need to characterize the origin of different methane (CH4) sources has led to the widespread application, by the international scientific community, of the isotopic measurement of δ13C which allows analyzing the possible contribution of the different sources to the atmospheric methane. Measuring the ratio of the stable isotopes 13C and 12C, and its variability, allows to differentiate if the methane emissions have occurred from livestock, bodies of water, industries, and other natural or anthropogenic sources.

In November 2015, intensive large-scale campaigns of atmospheric CH4 concentrations were carried out in the rural area of Gredos and Iruelas (Central Spain) using a Cavity Ring-Down Spectroscopy (CRDS, Picarro G2301) instrument mounted on a car. The work was realized within the framework of the project ‘Methane Interchange over the Iberian Peninsula’ led by the Catalan Institute of Climate Science (Spain). During these transects air flasks samples were also collected at 6 different points and then analyzed at the Laboratoire des Sciences du Climat et l&apos;Environnement (France) using a G2201-i Picarro instrument to perform an isotopic characterization of the measured methane.  Atmospheric CH4 concentrations were also continuously measured at two fixed sites during the campaigns.

Results of the spatial distribution and of the isotopic signature of the local methane emissions will be presented and discussed here.     

 

141 Understanding and modelling the response of high latitude ecosystems to extreme meteorological events with the ORCHIDEE land surface model

Oral

Amélie Cuynet*, Catherine Ottlé, Elodie Salmon

Laboratoire des Sciences du Climat et de l&apos;Environnement, Gif-sur-Yvette, France

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

With the ongoing climate change, high northern latitudes are experiencing an increasing frequency of extreme meteorological events, such as heat waves, snow-rich years, extreme precipitation or, conversely, droughts. Such events can drastically disrupt soil and vegetation dynamics, especially in permafrost environments, which are sensitive to temperature and soil water content. To study this sensitivity, we will analyse several sites, including certain ICOS sites known for enduring such extreme events. The first step is to study the meteorological time series and to infer the event’s amplitude by analysing the anomalies compared to the climatology of the site. To this end, local meteorological measurements are exploited to account for the site-specific characteristics in parallel with reanalyses to extend the data series. A second part then focuses on analysing the ecosystem response to each extreme event. That includes soil temperature and water content, LAI and greenhouse gas fluxes. Finally, we will check the ability of the land surface model ORCHIDEE to represent the impacts of each extreme event on the biosphere by forcing the model with the observed meteorological variables and by comparing the simulated results with the observations.

 

142 Preferential combustion of ethane during incomplete combustion of natural gas leads to underestimation of thermogenic methane contribution

Poster

Roisin Commane1*, Andrew Hallward-Driemeier1, Yuwei Zhao1, Luke Schiferl1,2

1Columbia University, New York, USA. 2Harvard University, Boston, MA, USA

Session 1. Isotopes and other tracers for studies of methane sources and sinks

The fraction of natural gas in mixed methane (CH4) source areas is often quantified by comparing the observed atmospheric ethane (C2H6):CH4 ratio to that reported in the pipeline. However, this approach assumes no change in the C2H6:CH4 ratio during the natural gas combustion process. We observed depleted ethane (lower C2H6:CHratios) in combustion plumes with high carbon monoxide (CO) at a rooftop observatory in New York City (Jan-June over multiple years). In order to determine the source of the incomplete combustion, we sampled the stack exhaust from a natural gas boiler and found badly operated boilers can release CH4, C2H6 and CO during the incomplete combustion of natural gas, but with C2H6 depleted relative to the C2H6:CH4 ratio of the incoming pipeline. Previous studies using ethane:methane would have underestimated the natural gas contribution of methane emission if they assumed an unchanged C2H6:CH4 ratio.

 

143 Addressing forest canopy decoupling in eddy covariance flux measurement networks

Oral

Georg Jocher1,2*, Natalia Kowalska1, Heping Liu3, Sonia Wharton4, Leonardo Montagnani5, Dario Papale6

1Global Change Research Institute CAS, Brno, Czech Republic. 2Thünen-Institut für Agrarklimaschutz, Braunschweig, Germany. 3Washington State University, Pullman, USA. 4Lawrence Livermore National Laboratory, Livermore, USA. 5University Bolzano, Bolzano, Italy. 6University Tuscia, Viterbo, Italy

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

The eddy covariance (EC) method is the standard technique for determining forest ecosystem-atmosphere turbulent exchange, however, it encounters a significant challenge: the air masses below the canopy often become decoupled from the air masses above it. Consequently, the EC measurements of scalar fluxes (e.g. H2O and particularly CO2) above the canopy can be biased due to missing signals from below-canopy processes. 

Multiple approaches have been developed in the recent decades to address decoupling (e.g. u* filtering, quality flags, storage change evaluations, advection measurements), however, all of them appeared to be insufficient to fully tackle the problem. A promising additional approach is based on subsequent EC measurements below and above the canopy. 

To date, there is no standardized approach to address decoupling yet. A specialized working group within ICOS strives for addressing this by conducting an extensive multi-site experiment. This multi-site experiment aims to

i) evaluate the performance of different types of sonic anemometers below canopy for decoupling investigations, 

ii) explore the spatial heterogeneity of below canopy processes in relation to decoupling, 

iii) develop a robust procedure to integrate decoupling investigations in the standard processing of EC measurement networks.

The anticipated experimental design involves three testing sites, namely a deciduous broadleaf forest in flat terrain (Lanžhot, Czech Republic), a coniferous forest in mountainous terrain (Renon, Italy), and a tall evergreen needleleaf forest in moderately complex mountain-valley terrain (Wind River, USA). 

This presentation will set the proposed experiment on a solid theoretical background, introduce the measurement design and discuss the experiment aims.

 

144 Simulated Detection of Methane Emissions from Arctic Permafrost Thawing Contribution with Atmospheric Radiocarbon and Other Tracer Measurements

Oral

Alina Yang1*, Heather Graven1, Anita Ganeson2, Rebecca Ward2

1Imperial College London, LONDON, United Kingdom. 2University of Bristol, Bristol, United Kingdom

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Permafrost underlies about 25% of the land in the northern hemisphere and contains over half of global soil carbon. Notably, the Arctic temperature is rising four times faster than the global average. The rising temperature due to global warming induces microbial decomposition of frozen organic carbon, leading to significant soil carbon loss through the release of carbon dioxide and methane. Although various studies have shown concerns towards methane released from thawing permafrost, the scope of its influence and precise contribution to global atmospheric methane levels remains uncertain. Recent atmospheric CH4 data have indicated that Arctic CH4 emissions have increased in summer and autumn; however, the attribution to permafrost carbon vs recently fixed carbon or fossil fuels is still lacking. Here we present simulations for Arctic sites in Alaska and Siberia of radiocarbon (14C) and stable isotopes (13C, D) in atmospheric CH4 as well as atmospheric ethane to show how these observations could attribute regional CH4 emissions to permafrost carbon vs other sources. We consider differences in the age of permafrost carbon in different regions that determine the depletion of 14C due to radioactive decay in permafrost carbon. Our results are important to assessing regional-scale Arctic CH4 sources and potential climate change tipping points, and they will be used to inform the planning of future atmospheric measurements.

 

145 Inversion of anthropogenic and biospheric CO2 fluxes in the city of Zurich from a network of mid-cost CO2 sensors

Oral

Nikolai Ponomarev*, Michael Steiner, Erik Koene, Lionel Constantin, Pascal Rubli, Stuart Grange, Lukas Emmenegger, Dominik Brunner

Laboratory for Air Pollution/Environmental Technology, Empa, Swiss Federal Laboratories for Materials Sci-ence and Technologies, Dübendorf, Switzerland

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Inverse modelling has become an important tool supporting climate change mitigation as it allows estimating greenhouse gas emissions from atmospheric observations. Since July 2022, a dense COsensor network with 208 low- and 27 mid-cost sensors has been operating in the city of Zurich in the framework of the ICOS-Cities PAUL project. Together with measurements at three background sites, these sensors provide detailed information on the spatial gradients and temporal variability of CO2 within the city and between the city and its surroundings. We estimate anthropogenic and biospheric CO2 fluxes from these observations using the ICON-ART atmospheric transport model in combination with the ensemble Kalman smoother inversion framework CTDAS. For the results presented here, we only assimilated observations from the background sites and the mid-cost sensors installed on rooftops (14 locations), as they are least influenced by local sources that cannot be resolved by the ICON-ART model. The ICON-ART simulations of meteorology and CO2 were performed for two coupled domains: Europe at 6.5 km resolution and a 60 km wide domain centered on Zurich at 0.5 km resolution. Differences in observed and modelled concentrations were then linearly mapped to flux changes using the ensemble Kalman smoother approach implemented in CTDAS. We find largest differences between prior and posterior fluxes during the winter 2022-2023 especially during the Christmas holidays which corresponds well to the electricity consumption data in the city. 

Acknowledgements: ICOS-Cities/PAUL, has received funding from the European Union&apos;s H2020 Programme under grant agreement No. 101037319

 

146 Influence of meteorological conditions on a young beech forest gross primary productivity: Insights from 24 year-long measurements using a novel wavelet-based approach

Oral

Jonathan Bitton*, Catherine Charles, Bernard Longdoz, Bernard Heinesch

Gembloux Agro-Bio Tech - University of Liege, Gembloux, Belgium

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Forests, as vital carbon sinks, face mounting challenges due to the increasing frequency of extreme events. These events, particularly heatwaves, storms and droughts, highlight the need of understanding how forests respond to environmental stresses. To tackle this challenge, long-term studies provide a unique lens through which we can unravel the intricate dynamics of forest ecosystems and their relationship with climatic fluctuations. In this context, our research focuses on a 24-year dataset of continuous CO2 measurements from the recently ICOS-labelled Hesse site, a beech-dominated forest under temperate conditions in north-eastern France. We introduce a novel approach using the continuous wavelet transform, a time-frequency analysis tool, to define indicators of gross primary productivity (GPP) intra-annual dynamics. Our study uncovers critical temporal windows during which current or previous year meteorological conditions significantly impact beech photosynthetic activity and eco-physiological behavior. Notably, precipitations during a 1–2 week period in July-August emerges as a pivotal phase for next year’s GPP dynamics. Furthermore, radiation, air temperature, vapor pressure deficit, precipitations and soil water availability exhibit both short and long-term effects on GPP. Our proposed approach disentangles these influences, identifying dominant periods for each variable and their localized impact on GPP dynamics. By unraveling these correlations, our study provides insights supporting a comprehensive understanding of forest resilience and yields critical information for developing sustainable forest management strategies in response to shifting climate patterns.

 

147 UAV Based In-situ Measurements of CO2 and CH4 Emissions

Oral

Abdullah Bolek1*, Martin Heimann1,2, Mathias Goeckede1

1Max Planck Institute for Biogeochemistry, Jena, Germany. 2Institute for Atmospheric and Earth System Research, University of Helsinki, Helsinki, Finland

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

Heterogeneous landscapes, such as Arctic permafrost regions, induce significant variations in carbon fluxes (CO2 and CH4) even on small spatial scales, leading to biases in upscaling the carbon fluxes from eddy-covariance towers and flux chambers due to their limited spatial representativeness. To mitigate these inherent biases, unmanned aerial vehicle (UAV) based measurements may complement the existing carbon monitoring network. However, only a few studies focused on UAV-based greenhouse gas (GHG) measurements.

This study introduces a recently developed UAV platform equipped with two portable gas analyzers to measure the concentrations of CO2 and CH4, along with an anemometer to measure 2D wind speed, air temperature, humidity, and pressure. The UAV platform was tested within the sub-Arctic permafrost peatland in Northern Sweden (Stordalen Mire). Grid flights were used to generate concentration maps of GHGs to assess the signal variability and to identify potential hotspots. Additionally, vertical profile flights were conducted to resolve the lowest part of the atmospheric boundary layer. These vertical profile flights were used to quantify the GHG fluxes and the comparison was made using the ICOS eddy-covariance tower within Stordalen Mire. Although subjected to large uncertainties over the area of interest, the comparison between the eddy-covariance method and UAV-based calculations showed acceptable qualitative agreement. 

 

148 Towards a multi-platform open-ocean observatory

Poster

Anita Flohr*, Susan Hartman, Edward Mawji, Pablo Trucco Pignata, Socratis Loucaides, Andrew Gates

National Oceanography Centre, Southampton, United Kingdom

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

The Porcupine Abyssal Plain sustained observatory (PAP-SO) is an ICOS-labelled fixed ocean station and part of the OceanSITES network of year-round measurements situated in the Northeast Atlantic (49°N 16.5°W, 4850 m). PAP-SO is one of the longest running open-ocean multidisciplinary observatory in the oceans around Europe. The site has produced high-resolution datasets integrating environmental and ecologically relevant variables from the surface to the seabed for >20 years.  Since 2002, a mooring has been in place with autonomous sensors measuring Essential Ocean Variables (EOVs) in the surface ocean. EOVs include temperature, salinity, dissolved oxygen, chlorophyll-a fluorescence, nitrate and pCO2 in high temporal resolution. Since 2010, the collaboration between the UK’s Meteorological Office and Natural Environment Research Council delivers simultaneous, open-access atmospheric and surface ocean datasets in near real-time.

Observatory research is increasingly focused on the causes and consequences of multidecadal change and on monitoring EOVs. To do this the infrastructure is being advanced steadily (e.g. moving towards pCO2 sensors with reference gas measurements) as is the use of different platforms (e.g. deploying BGC-ARGO floats and gliders) helping to improve data quality control of moored sensors. The site attracts process studies and novel technology trials alongside established techniques as part of (inter)nationally funded collaborations and demonstrator missions due to the extensive in-situ measurements available. Here we present ongoing future technology developments that will advance the transition of PAP-SO to a cost-effective multi-platform observatory for sustained carbon observations.

 

149 Modelling carbon recovery time after clear-cutting or fire in boreal forests under changing climate

Poster

Md. Rafikul Islam1*, Anna Maria Jönsson2, John Bergkvist2, Julia Kelly1, Fredrik Lagergren2, Irene Lehner1, Mats Lindeskog2, Meelis Mölder2, Lars Nieradzik2, Marko Scholze2, Natascha Kljun1

1Centre for Environmental and Climate Science, Lund University, Lund, Sweden. 2Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The boreal forest covers approximately 12 million km² and contains one-third of the terrestrial vegetation carbon, making it a vital component of the global carbon cycle. The impact of forest harvesting (e.g. clear-cuts) and forest fires on forest carbon budgets under climate change is still not well understood. This study presents results from simulations with the process-based dynamic global vegetation model LPJ-GUESS conducted for the boreal forests of Sweden, specifically at Norunda (ICOS) and at a forest in the Ljusdal area (central Sweden). At Norunda, we simulated the clear-cut of a 120-year-old mixed pine-spruce forest and a subsequent set of reforestation approaches. In Ljusdal, where forests were severely affected by wildfire in 2018, we conducted simulations of the forest fire and several post-fire management options with LPJ-GUESS and the fire module SIMFIRE-BLAZE. The model outputs were validated against in-situ observational data (eddy-covariance carbon fluxes, forest characteristics) from the forest stands. Both studies included simulations until the year 2100 following two distinct climate scenarios. We estimated the carbon recovery time using the carbon compensation point (CCP) following clear-cut or forest fire. We found that the CCP for different types of reforestation approaches at Norunda ranged from 12-16 years. For the Ljusdal forest, CPP was reached only 18-33 years following the forest fire and subsequent reforestation strategies, mostly due to carbon-dioxide emissions during the fire. These findings could guide the adoption of suitable reforestation strategies after clear-cutting or wildfires to maximize carbon recovery in boreal forests.

 

150 To what extent does CO2 diurnal cycle impact carbon flux estimates in CarboScope?

Oral

Saqr Munassar1*, Christian Rödenbeck1, Michał Gałkowski1, Frank-Thomas Koch2, Kai Uwe Totsche3, Santiago Botía1, Christoph Gerbig1

1MPI-BGC, Jena, Germany. 2DWD, Hohenpeißenberg, Germany. 3FSU, Jena, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Our study focuses on quantifying the impact of the CO2 diurnal cycle on the annual carbon fluxes estimated with the CarboScope (CS) atmospheric inversion at regional, continental, and global scales for the period of time 2010–2020. Biogenic fluxes of hourly Net Ecosystem Exchange (NEE) obtained from the data-driven FLUXCOM estimates are used in the inversion together with global and regional atmospheric transport models. Results demonstrate differences between CO2 mixing ratios simulated with daily averaged and hourly NEE. As a consequence, these differences lead to systematic biases in CO2 flux estimates when ignoring the diurnal variations of the CO2 flux in the atmospheric inversions. Although the impact on the global average of estimated annual flux is negligible, significant biases are found in the annual flux budgets at continental and regional scales. For Europe, the annual mean difference in the fluxes arising from the diurnal cycle of CO2 represents around 48% of the annual posterior fluxes (0.31 Pg C yr-1) estimated with CarboScope-Regional. Furthermore, the differences in NEE estimates calculated with CS increase the magnitude of the flux budgets for some regions such as northern American temperate and northern Africa by a factor of about 1.5. To the extent that FLUXOM diurnal cycles are realistic at all latitudes and for the station set used in our inversions here, we conclude that ignoring the diurnal variations in the land CO2flux leads to overestimation of both CO2 sources in the tropical lands and CO2 sinks in the temperate zones.

 

151 A dynamic soil, plant, animal and atmosphere modelling system for NH3 exchange in grazed grasslands

Oral

Mubaraq Olarewaju Abdulwahab1*, Anne-Isabelle Graux2, Andrea Móring3,4, Valérie Viaud1, Yannick Fauvel1, Christophe Fléchard1

1INRAE, Institut Agro Rennes-Angers, SAS, 35000, Rennes, France. 2PEGASE, INRAE, Institut Agro, 35590, Saint-Gilles, France. 3The University of Edinburgh, School of GeoSciences, Edinburgh, United Kingdom. 4Gedeon Richter Plc., Budapest, Hungary

Session 2. Exchange of reactive gases and aerosols between the land surface and the atmosphere in natural and managed ecosystems

The bidirectional exchange of ammonia (NH3) between the biosphere and the atmosphere in grazed grassland ecosystems is controlled by complex interactions between soil, vegetation, animals, and atmospheric processes. Conceptualized using resistance transfer models, the net NH3 exchange results from fluxes in plant stomatal and cuticular pathways, soil surface nitrogen (N) dynamics associated with urea hydrolysis, meteorological conditions and environmental variability.  The  Generation of Ammonia from Grazing model (GAG), developed originally for an extensively managed grassland in the UK, was tested and further adapted to the intensively grazed grassland ICOS flux tower station at FR-Mej (Méjusseaume,  NW France). Here, surface-atmosphere flux measurements of NH3 were carried out using the aerodynamic gradient method, and  CO2, H2O, N2O, and CH4 fluxes were measured by eddy covariance. Supplementary ecological data (soil mineral N, plant canopy height, leaf area index (LAI), above-ground biomass, animal presence, organic and mineral fertilization and high-resolution meteorological and soil physical variables) have been collected since 2020. The initial application of GAG highlighted limitations in accurately predicting grazing-induced NH3 fluxes. To address this, we introduced dynamic LAI and canopy height seasonality and updated the model equations to enhance the representation of plant (stomatal) resistances and in-canopy transfer, thereby reducing flux biases. Our ongoing work involves refining soil processes (including soil ammonium adsorption) to address the positive post-grazing NH3 flux biases and conducting sensitivity analysis of the GAG model. Through this, we aim to advance our understanding of NH3 emissions and their impact on nutrient cycling in grazed grasslands, capturing the complexity of the soil-plant-animal-atmosphere system.

 

152 14CO2-based Fossil Fuel CO2 Flux Estimation in Zurich Using Relaxed Eddy Accumulation

Poster

Ann-Kristin Kunz1*, Lars Borchardt2, Dominik Brunner3, Jia Chen4, Andreas Christen5, Lionel Constantin3, Markus Eritt2, Rainer Hilland5, Natascha Kljun6, Richard Kneißl2, Virgile Legendre2, Junwei Li4, Betty Molinier6, Stavros Stagakis7, Samuel Hammer8

1Heidelberg University, Heidelberg, Germany. 2Max Planck Institute for Biogeochemistry, Jena, Germany. 3Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland. 4TUM School of Computation, Information and Technology, Munich, Germany. 5University of Freiburg, Freiburg, Germany. 6Lund University, Lund, Sweden. 7University of Basel, Basel, Switzerland. 8ICOS CRL, Heidelberg University, Heidelberg, Germany

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Cities are hotspots for fossil fuel CO2 (ffCO2) emissions, but biospheric and human respiration fluxes can be significant sources of uncertainty for independent top-down validation of ffCO2 emissions. While regional atmospheric CO2 concentration signals can be separated into fossil and non-fossil contributions by 14COanalyses, direct measurements of ffCO2 fluxes with the eddy covariance (EC) method have so far not been possible due to a lack of fast-response 14COgas analyzers. To overcome this limitation, a novel relaxed eddy accumulation (REA) system was developed within the ICOS Cities project that for the first time allows 14CO2-based estimation of ffCO2 fluxes over an urban area.

During the ICOS Cities Zurich campaign from July 2022 to April 2023, the inlets of the ICOS REA system were installed on a 16.5 m high mast on top of a 95 m high-rise building near the city center of Zurich, Switzerland. Based on the 20 Hz vertical wind of a co-located EC system (IRGASON, Campbell Scientific), samples were diverted into updraft and downdraft flasks, excluding a deadband. 103 flask pairs were selected for 14CO2 analysis based on suitable micro-meteorological conditions. We present the first 14CO2-based CO2 flux partitioning and compare the observed results with estimates from the Zurich emission inventory and from a high-resolution VPRM model considering the specific flux footprints during the sampling intervals. A generally small signal-to-noise ratio of measured ffCOconcentration differences is the main challenge of this new technique. We therefore discuss measures to increase the ffCOflux signals for future campaigns. 

 

153 Terrestrial flux products from an extended data-driven scaling framework, FLUXCOM-X

Poster

Sophia Walther1*, Jacob A. Nelson1, Fabian Gans1, Basil Kraft1,2, Ulrich Weber1, Gregory Duveiller1, Zayd M. Hamdi1, Weijie Zhang1, Martin Jung1

1Max-Planck-Institute for Biogeochemistry, Jena, Germany. 2Eidgenössische Technische Hochschule, Zurich, Switzerland

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Mapping in-situ eddy covariance measurements (EC) of terrestrial carbon and water fluxes to the globe is a key method for diagnosing terrestrial fluxes from a data-driven perspective. We describe the first global products (called X-BASE) from a newly implemented up-scaling framework, FLUXCOM-X. The X-BASE products cover the globe at 0.05° spatial resolution for every hour and include estimates of CO2 net ecosystem exchange (NEE) and gross primary productivity (GPP).

Compared to previous FLUXCOM products, the new X-BASE NEE better reconciles the bottom-up EC-based NEE and estimates from top-down atmospheric inversions (global X-BASE NEE is -5.75±0.33 PgC yr-1). The improvement of global NEE was likely only possible thanks to the international effort to improve the precision and consistency of eddy covariance collection and processing pipelines, as well as to the extension of the measurements to more site-years resulting in a wider coverage of bio-climatic conditions. However, X-BASE NEE shows low inter-annual variability, which is common to state-of-the-art data-driven flux products and remains a scientific challenge.
   With 124.7±2.1 PgC yr-1, X-BASE GPP is slightly higher than previous FLUXCOM estimates, mostly in temperate and boreal areas, and temporal patterns agree well with TROPOMI-based SIF.

Many further opportunities for development exist. We will outline how the new FLUXCOM-X framework provides the necessary flexibility to experiment, diagnose, and converge to more accurate global flux estimates. Pathways of exploration include methodological choices in the selection and processing of eddy-covariance and satellite observations, their ingestion into the framework, and the configuration of machine learning methods.
   

154 Carbon Fluxes along the GB Land Ocean continuum

Poster

Richard Sanders1*, Elena Garcia-Martin2, Andrew Tye3, Dorothee Bakker4, Chris Evans5, Dan Mayor6, Ruth Matthews4

1NORCE, Bergen, Norway. 2NOC, Southampton, United Kingdom. 3British Geological Survey, Nottingham, United Kingdom. 4University of East Anglia, Norwich, United Kingdom. 5Centre for Ecology and Hydrology, Bangor, United Kingdom. 6University of Exeter, Exeter, United Kingdom

Session 7. Carbon Cycling along the Land Ocean Aquatic Continuum

ICOS is established around a conceptual model of the global carbon (C) cycle consisting of  fluxes between the atmosphere and the land surface and ocean. Atmospheric CO₂ accumulates at approximately 5 Gt C yr-1 ,with the difference between emissions and accumulation entering the ocean and terrestrial biosphere. The other major flux between land and ocean is much less well understood, although it is clear that it may be changing and that a substantial fraction of land-derived C enters the atmosphere in rivers and estuaries. This uncertainty is substantially caused by the multiple steps in this flux including C losses from soils and underlying geology to rivers and the subsequent transfer of a fraction of this material through the Land Ocean Aquatic Continuum (LOAC; rivers, estuaries, coastal shelf seas and the open ocean). There are very few regions where we have a good understanding of the losses to the atmosphere at the various stage s of this transfer. One such environment is Great Britain (GB), a large temperate island in the Northern Hemisphere with high spatial variation in population intensity, underlying geology, peatlands, agricultural development and forestry located in a shallow coastal shelf sea that links through to the open ocean. Over 2014-2017 multiple field programmes worked on the GB LOAC C Cycle. Here we will describe the breadth of this field programme, present highlights from each sector, and bring the data together to estimate the fate of the C emitted from the GB landscape and the factors which control this. 

 

155 The ICOS Ocean Thematic Centre: How we can support you in providing data to estimate the Ocean Carbon Sink

Poster

Richard Sanders1*, Tobias Steinhoff1, Ingunn Skjelvan1, Socratis Loucaides2, Ute Schuster3, Andrew Watson3, Stephen Jones4, Nicole Dalton3

1NORCE, Bergen, Norway. 2NOC, Southampton, United Kingdom. 3University of Exeter, Exeter, United Kingdom. 4University of Bergen, Bergen, Norway

Session 17. Best Practices in the landscape of Research Infrastructures: Cooperation, Co-location and other lessons learned

The Ocean has taken up approximately 25% of the CO2 we have emitted to the atmosphere (Anthropogenic Carbon), slowing the rate of climate change.. The future trajectory of this uptake will determine the cost and efficacy of any  mitigation and adaptation actions we can take to keep climate change impacts within manageable boundaries. Obtaining accurate and up to date estimates of ocean Carbon uptake is crucial for the production of high-quality information products such as the Global Carbon Project produces annually for the Conference of Parties (COP). We know that Ocean Carbon uptake varies widely in space and time and hence large quantities of high quality information is required to track this uptake with high confidence. In Europe, this is provided by the Ocean component of the Integrated Carbon Observation System (ICOS), which consists of multiple ocean measuring stations. These are on research and merchant vessels and on moorings that measure surface CO2 concentrations,  reporting these data to international databases such as SOCAT. The ICOS Ocean Thematic Centre supports this effort by advocating for its ongoing funding within fora such as the WMO, by providing standards, training and software solutions, by supporting technology innovation and by auditing station operations and data quality (a process known in ICOS as labelling). In this presentation we will give an overview of key activities in each area that we have been undertaken over the last two years and provide an overview of plans for the future. 

 

156 Estimating European CH4 fluxes using the CarboScope Regional atmospheric inversion system

Poster

Frank-Thomas Koch1*, Saqr Munassar2, Christian Roedenbeck2, Luana Basso2, Christoph Gerbig2

1Meteorological Observatory Hohenpeissenberg, Deutscher Wetterdienst, Hohenpeissenberg, Germany. 2Max Planck Insitute for Biogeochemistry, Jena, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

With an increasing network of atmospheric stations that produce a continuous data stream, top-down inverse transport modelling of GHGs in a quasi-operational way becomes feasible.
   
   The CarboScope regional inversion system embeds the regional inversion within a global inversion using the two-step approach. The regional CHinversion uses Lagrangian mesoscale transport from STILT, prior fluxes for peatlands, mineral soils, biomass burning, termites, anthropogenic emissions from EDGAR v6.0, and ocean fluxes. 

The protocol for the inversion follows a protocol of a methane regional inversion intercomparison project for Europe and was applied for running inversions for the period 2006-2020. The domain covers most of Europe (33 – 73N, 15W – 35E) with a spatial resolution of 0.25 degree for fluxes and 0.5 degree for flux corrections inferred by the inversion.
   
   Results for the posterior methane fluxes and uncertainties for the full period 2006-2020 are presented on annual and monthly temporal scale. The sensitivity of the regional inversion results to the far field contributions derived from global methane inversions will be discussed.

 

157 Towards reconciling terrestrial CO2 flux estimates from regional and global data-driven up-scaling approaches

Oral

Sophia Walther1*, Anna Virkkala2, Jacob A. Nelson1, Isabel Wargowsky2

1Max-Planck-Institue for Biogeochemistry, Jena, Germany. 2Woodwell Climate Research Center, Falmouth, USA

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Combining in-situ measurements of terrestrial CO2 fluxes with relevant information on environmental conditions from in-situ and satellite observations using machine learning is a key method for mapping terrestrial fluxes to regional or global domains. It offers a scalable complementary perspective to process-based models. In the ABZ, this is particularly valueable because the latter still have large uncertainties in representing the dynamics of vegetation, permafrost, and hydrology, with strong implications given the large soil carbon stocks it holds and the potential to trigger global climate feedbacks.
   
   However, data-driven upscaling is inherently dependent on data quantity, quality, the representativeness of flux data, and the relevance of predictors. Observational conditions, both in-situ and spaceborn, are particularly challenging in the ABZ. Modeling the ABZ can therefore potentially benefit from domain specific data streams, such as additional flux data from chambers and observational proxies such as permafrost status.
   
   We systematically explore data-driven terrestrial CO2 flux estimates  in the ABZ originating from  products with both a focus on ABZ (Virkkala et al. 2021,GCB) and the global domain (Nelson* & Walther* et al. 2024,BGS). We aim at understanding the robustness of  flux magnitudes and their spatiotemporal dynamics. We further explore how the temporal resolution (ranging from subdaily to monthly) as well as how tailoring predictors and training samples to a specific domain can impact CO2 fluxes. Our work is a step towards better understanding the performance of global and regional upscaling efforts and quantifying CO2 exchange in the vulnerable and spatially heterogeneous ABZ.
  

158 Integrating scenario planning and real-time monitoring for urban GHG emissions management

Poster

Angelica Centanaro*, Hervé Utard, Arthur Pécondon-Lacroix, Jinghui Lian, Laurent Millair, David Duccini

Origins.earth, Paris, France

Session 12. Translating Scientific CO2 Emission Research into City Services

In the pursuit of NetZero targets, effective policy implementation is pivotal in reducing urban greenhouse gas (GHG) emissions. However, a notable disparity often exists between cities&apos; objectives and the resultant policy outcomes, often due to a lack of clear metrics for measuring policy impact. Origins is pioneering a holistic solution that integrates data management as well as a real-time monitoring network for monitoring urban emissions.

Origins started developing a novel scenario planning tool, capable of simulating GHG emission trajectories under diverse policy interventions. These interventions span building renovations, heating network implementations, modal shifts in mobility, and energy efficiency measures. Through rigorous simulation, cities can tailor comprehensive climate action plans aligned with their specific objectives and constraints.Our target is to provide a global solution that can go beyond scenario planning by incorporating a robust monitoring framework that enables cities to track the actual outcomes of implemented policies.

While still in the developmental phase, our project has already produced promising preliminary results, including the creation of future emission maps based on scenario projections. Initial observations from Paris showcase the potential of our approach to inform evidence-based urban sustainability strategies.

In conclusion, our project represents a significant advancement in bridging the gap between policy intentions and tangible emissions reductions in urban contexts. By offering cities a comprehensive solution for scenario planning and monitoring, we aim to empower them in their journey towards achieving NetZero targets and building resilient, low-carbon communities.

 

159 Comparison of intra-urban energy exchange in vegetated vs metropolitan Mediterranean areas: the case study of the city of Naples

Poster

teresa Bertolini1*, terenzio Zenone1, Daniela Famulari2, Chiara Corradi1, Paul Di Tommasi3, Vincenzo Magliulo3, Michele Mattioni4, Gabriele Guidolotti4, Emanuele Pallozzi5, Piero Toscano6, Carlo Calfapietra4

1CNR IRET, Napoli, Italy. 2CNR IBE, Bologna, Italy. 3CNR ISAFOM, Portici, Italy. 4CNR IRET, Porano, Italy. 5CNR IRET, Montelibretti, Italy. 6CNR IBE, Firenze, Italy

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

The constant growth of population living in urban areas creates new opportunity for Urban Green Areas (UGA) to provide ecosystem services for human wellbeing such as cooling effect and carbon neutrality of cities. In this study we investigated the seasonal intra-city surface energy flux  to compare the sensible/latent heat fluxes between building areas and a UGA using simultaneous eddy covariance observations in both locations. Here we show that the UGA cooling capacity and carbon uptake are influenced by water availability: multivariate analysis indicates that solar radiation (Rg) was the primary control factor in latent heat (LE) and CO2 fluxes followed by the air temperature (Tair) and vapor pressure deficit (VPD). The relative importance of VPD was higher in year characterized by drought conditions. As expected sensible heat was larger at the urban site especially around midday in the summer months and throughout the year during nighttime. Latent heat flux at the UGA was characterized by typical daily and seasonal trends while at the urban site it showed a larger variability with not well defined trend. The larger H fluxes could potentially lead to a local increase in the air temperature (above the building) compared to the UGA characterized by larger LE that could lead to a local cooling effect on air temperature. 
 

160 Sustainable use of peatlands for agriculture in the Arctic

Poster

Junbin Zhao1*, Mikhail Mastepanov2,3,1, Cornelya Klutsch4, Erling Fjelldal4, David Kniha4, Runar Kjær4

1Norwegian Institute of Bioeconomy Research, ÅS, Norway. 2Aarhus University, Roskilde, Denmark. 3Oulu University, Kuusamo, Finland. 4Norwegian Institute of Bioeconomy Research, Svanhovd, Norway

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Peatlands hold immense soil carbon (C) reserves. Since the 1930s, vast expanses of peatlands in northern Norway have been drained and converted to agricultural land. This drainage disrupts the ecosystem&apos;s hydrology, favoring peat decomposition and transforming peatlands into substantial sources of greenhouse gases (GHGs). To mitigate GHG emissions while sustaining biomass production, various management practices, including rewetting, are being advocated. However, the effects of these mitigation measures on the peatland GHG balance remain largely unexplored in high latitude regions.

We investigated productivity and GHG balance in response to peatland cultivation under varying fertilization and hydrological treatments. The research site lies within the Pasvik valley, Arctic Norway, where grasses are cultivated. GHG fluxes (CO2, CH4, and N2O) were measured from 10 plots exhibiting five water levels and two fertilization levels at a sub-daily interval utilizing automatic chambers during the 2022 and 2023 growing seasons. Elevated water levels can inhibit net CO2 emissions, converting the ecosystem from a CO2 source to a sink. However, high water levels also enhance the CH4 emissions. Sporadic N2O emissions were observed to be higher under the more intensive fertilization regime. Further analysis will reveal the overall GHG budget and C balance in response to changes in water level, fertilization and harvesting frequency.  

Our results quantify peatland GHG potentials under different management scenarios and hold significant implications for guiding peatland management in a climate-friendly manner in high latitude regions.

 

161 Winter-time methane fluxes in boreal and arctic peatlands

Oral

Elodie Salmon1*, Xiaoni Wang-Faivre1, Amélie Cuynet1, Catherine Ottlé1, Bertrand Guenet2, Paul Miller3,4, David Wårlind3, Eyrún G. Gunnlaugsdóttir5, Xuefei Li5, Efrén López-Blanco6,7, Janne Rinne8, Mikhail Mastepanov6,7, Ivan Mammarella5, Jari-Pekka Nousu8

1Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS-Université Paris-Saclay, Gif-sur-Yvette, France. 2Laboratoire de Géologie, École normale supérieure-CNRS-PSL Univ., IPSL, Paris, France. 3Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden. 4Centre for Environmental and Climate Science, Lund University, Lund, Sweden. 5Institute for Atmospheric and Earth System Research (INAR) / Physics, University of Helsinki, Helsinki, Finland. 6Department of Ecoscience, Arctic Research Center, Aarhus University, Roskilde, Denmark. 7Department of Environment and Minerals, Greenland Institute of Natural Resources, Nuuk, Greenland. 8Natural Resources Institute Finland (Luke), Helsinki, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

In the Boreal and Arctic regions, the winter season extending from September to May, is twice as long as the summer season, during which peatlands can emit methane. While this contribution has been estimated from observations, global scale ecosystem models employed in the last model intercomparison underestimate winter-time methane fluxes. To investigate this likely discrepancy between observations and model estimations, we compared simulated winter-time methane fluxes from the two ecosystem models, LPJ-GUESS and ORCHIDEE with observations from 7 sites obtained between 2005 and 2023. Both models simulate soil methane production, oxidation and transport processes, enabling to determine the conditions that limit simulated total methane soil stocks and surface fluxes i.e., soil moisture, temperature and oxygen content. These variables are changing also owing to the snow that lessens gas exchange rate between the soil and the atmosphere during winter. The influence on the methane surface fluxes of snow accumulation, snow cover length and active layer thickness will also be assessed. Thus, we aim to identify which key processes influence methane emissions during the winter season to enhance model representation of boreal and arctic peatlands ecosystems.

 

162 Correlation between the CO2 time series of the Izaña atmospheric station and the ESTOC oceanic station.

Poster

Sergio Fabián León Luis1*, Melchor Dávila2, Pedro Pablo Rivas Soriano3, Aridane González2, Eric Delory4, Carlos Torres García3

1Tragsatec, Madrid, Spain. 2Institute of Oceanography and Global Change (IOCAG), University of Las Palmas de Gran Canaria (ULPGC), Las Palmas de Gran Canaria, Spain. 3Izaña Atmospheric Research Center (IARC), State Meteorological Agency (AEMET), Santa Cruz de Tenerife, Spain. 4Plocan, Las Palmas de Gran Canaria, Spain

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The Izaña atmospheric station located on the island of Tenerife at 2373 m.a.s.l. and the ESTOC Oceanic Station at 60 nautical miles north of the island of Gran Canaria, both integrated in ICOS-Spain, monitor in two different but interconnected domains, inside the global cycling of carbon and other greenhouse gases [1]. Moreover, the two stations are separated by a short distance (~100km), which allows for a global view of climate change in the eastern subtropical region of the North Atlantic. 

Izaña is normally located above a temperature inversion layer, generally well established over the island, and below the descending branch of the Hadley cell, which offers excellent conditions for in situ measurements of trace gases and aerosols in free troposphere conditions. Its continuous time series of CO2 concentrations started in 1984. Meanwhile, ESTOC started its measurement programme of the physical and chemical characteristics of ocean waters in 1994.

The first part of this work presents the time series of each station, showing the trends of the main greenhouse gases and other parameters specific to each domain. Subsequently, a comparison between the trends of both time series is presented in order to have a global perspective of the exchange of CO2 between the atmosphere and the ocean.

 

163 ICOS-Spain atmospheric stations detected transoceanic transport of emissions from Canadianfires over the North Atlantic

Poster

Sergio Fabián León Luis1*, José Antonio Adame Carnero2, Pedro Pablo Rivas Soriano3, Margarita Yela González4, Carlos Torres García3

1Tragsatec, Madrid, Spain. 2Atmospheric Sounding Station - El Arenosillo. National Institute for Aerospace Technology (INTA), Huelva, Spain. 3Izaña Atmospheric Research Center (IARC), State Meteorological Agency (AEMET), Tenerife, Spain. 4Dept. of Earth Observation and Space Science, National Institute for Aerospace Technology (INTA), Torrejón de Ardoz-Madrid, Spain

Session 13. In situ data for climate and other environmental services and policy support

The devastating wave of wildfires that affected Canada was international concern due to the enormous negative impact on air quality during the summer months of 2023. High temperatures, drought and prevailing meteorological conditions favoured the simultaneous occurrences of many wildfires throughout the country. The global atmospheric circulation with predominantly easterly winds over this region favoured the long-range transport of particles, allowing them to reach different European countries, including Spain. In addition to containing small particles, the plume contained a high concentration of carbon dioxide (CO 2 ) and carbon monoxide (CO) produced by the burning of biomass.

The atmospheric stations of ICOS-Spain, Izaña (Canary Islands) and El Arenosillo (south Iberian Peninsula) identified episodes where CO 2  and CO in situ concentrations experienced significant variations with respect to background conditions [1]. In this work, correlations between the variations of CO 2 and CO concentrations are shown for different episodes in both stations. In addition, the calculated back-trajectories are shown confirming the origin of air masses from Canada.

This event highlights the importance of understanding the dynamics of atmospheric circulation in order to study the potential negative impacts on a region due to events originating hundreds of kilometres away.

 

164 Towards an increasingly biased view on Arctic change

Oral

Efrén López-Blanco1,2*, Elmer Topp-Jørgensen1, Torben R. Christensen1,3, Morten Rasch4, Henrik Skov5, Marie F. Arndal1, M. Syndonia Bret-Harte6, Terry V. Callaghan7,8, Niels M. Schmidt1

1Department of Ecoscience, Arctic Research Center, Aarhus University, Roskilde, Denmark. 2Department of Environment and Minerals, Greenland Institute of Natural Resources, Nuuk, Greenland. 3Water, Energy and Environmental Engineering Research Unit, Faculty of Technology, Oulu University, Oulu, Finland. 4Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark. 5Department of Environmental Science, iClimate, Arctic Research Center, Aarhus University, Roskilde, Denmark. 6Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, USA. 7School of Biosciences, University of Sheffield, Sheffield, United Kingdom. 8Laboratory of Ecosystems and Climate Change, Tomsk State University (on hold), Tomsk, Russian Federation

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

The Russian invasion of Ukraine hampers the ability to adequately describe conditions across the Arctic, thus biasing our view on Arctic change. Our study benchmarks the pan-Arctic representativeness of the largest high-latitude research station network, INTERACT, with or without Russian stations. Multiple of these INTERACT stations include ICOS and FLUXNET flux towers measuring terrestrial carbon exchange dynamics across the pan-Arctic region. Our findings reveal pre-existing biases within the INTERACT network in representing key ecosystem conditions across the Arctic. Notably, INTERACT stations are predominantly situated in slightly warmer, wetter regions with deeper snow cover, and exhibit lower vegetation biomass and soil carbon stocks. Excluding Russian stations from INTERACT significantly increases the biases in all key ecosystem variables, decreasing our ability to describe (and project) Arctic changes accurately. In some cases the biases have the same magnitude as the expected shifts caused by climate change by the end of the century. At a broader scale, the loss of Siberian research stations may be particularly detrimental for the ability to track global responses to climate change such as thawing permafrost, shifts in biodiversity, and carbon dynamics. 

 

165 Using satellites in support of methane emission reductions

Oral

ilse aben1,2, joannes maasakkers1, berend schuit1,3, shubam sharma1, tobias de jong1, matthieu dogniaux1, itziar irakulis-loitxate4, Cynthia randles4, MEDUSA -team1

1sron Netherlands Institute for Space Research, Leiden, Netherlands. 2Vrije Universiteit, amsterdam, Netherlands. 3GHGSat, Montreal, Netherlands. 4UNEP, Paris, France

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

The importance of reducing methane emissions to mitigate climate change in the short term has been recognised at the highest political level. By now over 150 countries have signed up to the Methane Pledge to reduce emissions by 30% by 2030 compared to 2020. At COP28 (2023), the International Methane Emission Observatory (IMEO) launched the Methane Alert Response System (MARS) to detect and identify methane super-emitters using satellite data, notify responsible parties, and work together towards reducing their emissions. TROPOMI methane observations are at the core of the MARS system as TROPOMI is the first satellite instrument providing daily global observations of methane super-emitters.

We developed a machine learning approach to detect super-emitters in the TROPOMI data. These detections are used to tip-and-cue high spatial resolution satellites (e.g., GHGSat, Sentinel-2) to identify the exact sources. This way, we were able to identify super-emitting landfills, oil/gas facilities, and coal mines. We will show how this synergistic use of multiple satellites can be used to inform the operators, allowing – for example – gas leaks to be fixed and how the resulting emission estimates can be used to evaluate reported emissions.

We will also introduce the ESA MEDUSA project where we will compare the various satellite products on methane ‘point’ sources, provide a framework for methane flux uncertainty, and where possible validate these through controlled releases. In addition, we will perform a few case studies highlighting the potential of these point source/hot spot methane observations.

 

166 Methane emissions over major fossil fuel basins from bottom-up inventories and atmospheric inversions

Oral

Kushal Tibrewal1, Philippe Ciais1, Xin Lin1, Marielle Saunois1, Antoine Benoit2, Clement Giron2, Katsumasa Tanaka1,3, Jean Sciare4

1Laboratoire des Sciences du Climat et de l&apos;Environnement, Gif-sur-Yvette, France. 2Kayrros, Paris, France. 3National Institute for Environmental Studies, Tsukuba, Japan. 4The Cyprus Institute, Nicosia, Cyprus

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Fossil fuel production is a dominant contributor to the total anthropogenic methane emissions. However, there are large uncertainties in emissions estimates, especially for the oil and gas sector. We analyzed mean annual methane emissions during 2019-2021 for major fossil fuel basins to gauge the range in estimates reported across different datasets. The analysis included 14 basins contributing ~20% to global fossil methane emissions. Three coal basins – Shanxi (China), South Africa and Bowen-Surat (Australia); Ten oil and gas basins – two in North America (Permian, Anadarko), Algeria, Iraq, two in Iran, Kuwait, two in Turkmenistan and Uzbekistan; and One mixed-fuel basin in North America (Appalachian). Emissions are compared across a) regional inversions using bias-corrected methane column mixing ratios derived from TROPOMI on board the Sentinel 5P satellite, b) global bottom-up inventories – CEDS, EDGAR, GAINS, GFEIv2 and c) two ensembles of global inversions based on EDGAR and GAINS as priors respectively. Overall, both bottom-up inventories and global inversions underreport emissions over the basins compared to regional inversions. For all basins combined, the underreporting lies between -34% to -3%, while at the basin level, it can go as high as -96%. Further, regional inversions show a lower spread in estimates per basin than bottom-up inventories and global inversions. This reflects the influence of different data-sources for emissions factors across bottom-up inventories and influence of different inversion systems and combination of priors across global inversions. These findings contribute to improving the consensus among datasets for a better evaluation of global mitigation efforts.

 

167 Evaluation of selected Sentinel-2 remotely sensed vegetation indices and MODIS GPP in representing productivity in semi-arid South African ecosystems.

Poster

Amukelani Maluleke1*, Gregor Feig1,2, Christian Brümmer3, Abraham de Buys1, Guy Midgley4

1South African Environmental Observation Network, Pretoria, South Africa. 2Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Pretoria, South Africa. 3Thünen Institute of Climate‐Smart Agriculture, Braunschweig, Germany. 4Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

Large scale spatiotemporal assessments of production trends in semi-arid ecosystems rely on satellite data estimates, which often lack well-coordinated ground-based validation datasets, leading to biases. We used GPP estimates from the partitioning of net ecosystem measurements (net ecosystem exchange) from three ground-based Eddy Covariance (EC) flux tower sites and applied linear regressions to evaluate the ability of Sentinel‐2 vegetation indices (VIs) retrieved from Google Earth Engine to estimate GPP in semi‐arid ecosystems. The Sentinel‐2 normalized difference vegetation index (NDVI), enhanced vegetation index (EVI) and the land surface water index (LSWI) were each assessed separately, and also in combination with selected meteorological variables (incoming radiation, soil water content, air temperature, vapor pressure deficit) using a bi‐directional stepwise linear regression to test whether this can improve GPP estimates. The performance of the MOD17AH2 8‐day GPP product was also tested. While all VIs tracked the phase and amplitude patterns of ground-based GPP across the sites, they notably improved with the addition of meteorological variables. The least improvement in R2 was observed in all EVI-based estimates – indicating the suitability of EVI as a single VI to estimate GPP. Our results suggests that while a single VI is more advantageous for production assessments, incorporating meteorological variables can enhance the accuracy of single VI estimates in detecting and characterising changes in GPP. In addition, we found that standard MODIS products better represent the phase than amplitude of production in semi-arid ecosystems – underestimating by almost 50% and explaining between 68-83% of GPP variability.

 

168 The LOng-LIved greenhouse gas PrOducts Performances (LOLIPOP) CCI+ project

Oral

Elisa Castelli1*, Bianca Maria Dinelli1, Massimo Cardaci2, Massimo Valeri2, Gabriele Brizzi2, Antonio Bruno3, Martin Chipperfield4, Cathy Clerbaux5, Lieven Clarisse6, Pierre Coheur6, Martine De Mazière7, Sandip Dhomse4, Bart Dils7, Federico Fabiano1, Marco Gai8, Maya George5, Jeremy Harrison3, Michaela Imelda Hegglin9, Margherita Premuda1, Piera Raspollini8, Laura Saunders10, Reinold Spang9, Gabriele Stiller11, Corinne Vigoroux7, Kaley Walker10, Simon Whitburn6

1CNR-ISAC, Bologna, Italy. 2Serco-Italia, Frascati(RM), Italy. 3National Centre for Earth Observation at University of Leicester, Leicester, United Kingdom. 4National Centre for Earth Observation at University of Leeds, Leeds, United Kingdom. 5LATMOS/IPSL, Sorbonne Université, UVSQ, CNRS, Paris, France. 6Université Libre de Bruxelles, Bruxelles, Belgium. 7The Royal Belgian Institute for Space Aeronomy, Bruxelles, Belgium. 8CNR-IFAC, Sesto Fiorentino(FI), Italy. 9Research Centre Julich (FZJ), Julich, Germany. 10University of Toronto, Toronto Ontario, Canada. 11Karlsrhue Institute of technology, Karlsrhue, Germany

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

To fully understand the Earth’s climate, the impact of greenhouse gases (GHG) should be considered. High-quality datasets of their concentrations, measured by satellite instruments, are essential for this scope. Within the ESA Climate Change Initiative (CCI) program, atmospheric GHGs like ozone, water vapor, carbon dioxide and methane, have already been addressed. Nitrous oxide (N2O), sulfur hexafluoride (SF6), carbon tetrachloride (CCl4) as well as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and perfluorocarbons (PFCs), also known as the ‘Other long-lived greenhouse gases’ (OLLGHGs), are recognized as one of the GCOS Essential Climate Variables (ECVs). and their role as ozone-depleting substances and GHGs is widely known. However, GCOS includes user requirements for N2O only. 

The LOng-LIved greenhouse gas PrOducts Performances (LOLIPOP) CCI+ project aims to fill this gap. The goals of LOLIPOP are:

  • assess the state-of-the-art of OLLGHGs satellite measurements, 
  • provide user requirements for all the OLLGHGs, and compare them with the quality of the existing satellite observations,
  • investigate the quality of the existing satellite data with respect to selected applications in climate and atmospheric chemistry models and services.

The final goal of the project is to determine if the quality of the actual set of satellite measurements is good enough for their use in climate science and services. In this case, the construction of a harmonized and consistent dataset of satellite measurements can go ahead. 

We will present the work performed in the first part of the project, started in November 2023.

 

169 Expanded Freshwater and Terrestrial Environmental Observation Network: A Landscape Scale Environmental Research Infrastructure in South Africa

Oral

Gregor Feig1,2*, Kathleen Smart3, Warren Joubert4, Helga Knoetze5, Amukelani Maluleke6, Sylvester Selala4, Jeremy Moonsamy3, Sachin Doarsamy3, Nolusindiso Ndara1, Isaac Gura1, Marc Pienaar1, Abri De Buys4

1South African Environmental Observation Network (SAEON), Pretoria, South Africa. 2University of Pretoria, Pretoria, South Africa. 3South African Environmental Observation Network (SAEON), Pietermaritzburg, South Africa. 4South African Environmental Observation Network (SAEON), Cape Town, South Africa. 5South African Environmental Observation Network (SAEON), Kimberley, South Africa. 6South African Environmental Observation Network (SAEON), Hoedspruit, South Africa

Session 17. Best Practices in the landscape of Research Infrastructures: Cooperation, Co-location and other lessons learned

The Expanded Freshwater and Terrestrial Environmental Observation Network (EFTEON) is a research infrastructure that is being developed to support studies on coupled ecological and social systems in South Africa. The design is based on developing six distributed “landscapes”, each representing an important South African Ecosystem/Human complex. Each of the landscapes will have a standard set of automated instruments measuring the carbon and water cycles, meteorology, and air quality. A suite of standard repeated manual measurements covering biodiversity, productivity, ecosystem condition, ecosystem service provision and- use is being implemented. A larger set of subsidiary sites within each landscape, will have simpler standard automated instruments for climate and freshwater monitoring, as well as repeated manual measurements including socio-ecological survey data collection in surrounding communities. These landscapes cover the suite of biomes occurring in South Africa, including arid shrubland, tropical savanna, tropical grassland, high altitude mesic grassland, Afromontane forests, and fynbos, with a range of land use types and tenure systems being represented. This presentation will focus on infrastructure design and developments, and present some preliminary results highlighting activities in the RI, lessons learned and future priorities.

 

170 Lower-cost eddy covariance setups for increasing the spatial replication of CO2 and H2O flux measurements above agroforestry

Poster

José Ángel Callejas Rodelas1*, Alexander Knohl1,2, Justus van Ramshorst1,3, Iva Mammarella4, Timo Vesala4, Olli Peltola5, Christian Markwitz1

1Bioclimatology, University of Göttingen, Göttingen, Germany. 2Centre for Biodiversity and Land Use, University of Göttingen, Göttingen, Germany. 3Quanterra Systems Ltd., Centenary House, Peninsula Park, Exeter EX2 7XE, United Kingdom. 4Institute for Atmospheric and Earth System Research (INAR)/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland. 5Natural Resources Institute of Finland (LUKE), Helsinki, Finland

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

Conventional eddy covariance (CON-EC) studies typically lack spatial replication due to high instrumental costs. Lower-cost eddy covariance (LC-EC) setups, including slow response sensors for CO2 and H2O, might provide a potential solution to the spatial replication problem, despite the flux uncertainty mainly related to their larger high frequency response correction.

In this work, we present (i) a validation of three LC-EC setups for CO2 and latent heat (LE) flux measurements against a CON-EC setup above a monocropping site and one LC-EC setup above an adjacent agroforestry site; and (ii) results from a distributed tower network equipped with the same three LC-EC setups at the agroforestry system.

Results from the CON-EC and LC-EC comparison indicated a very good agreement of CO2 and LE fluxes with slopes of the linear regression models between of around 1.0 (R2=0.9) for CO2 and between 0.78 and 1.0 (R²=0.8) for LE fluxes. All setups detected (i) the ecosystem dynamics of CO2 and LE fluxes and (ii) differences between fluxes from open cropland and agroforestry.

Results of the distributed tower network indicated that the spatial variability in CO2 and LE fluxes was caused by differences in each tower’s footprints, due to changing wind directions, different fractions of crops seen by the towers, variability in phenology of the crops, and management activities. The information gained by the multiple-tower system counteracted the larger uncertainty associated to the LC-EC setups. These results support the use of LC-EC as a tool to study flux heterogeneity in complex land ecosystems.

 

171 Temporal trends in high-resolution flux of Nitrogen-Dioxide (NO2) from a grazed African Savanna

Oral

Tamryn Hamilton1,2*, Kerneels Jaars1, Pieter Van Zyl1, Warren Joubert2, Gregor Feig2

1North West University, Potchefstroom, South Africa. 2EFTEON, Pretoria, South Africa

Session 2. Exchange of reactive gases and aerosols between the land surface and the atmosphere in natural and managed ecosystems

South Africa is a major source for anthropogenic atmospheric NO2. Emissions from coal power generation and industrialized processes clustered together in the Mpumalanga Highveld form a well-known hotspot of elevated NO2 concentrations that influence air quality across the southern African region. Natural sources that contribute to NO2, such as soil emissions and biomass burning, are influenced by climate, geography and human activity. Whilst processes that remove atmospheric NO2, in the form of wet and dry deposition are associated with rainfall and landscape surface dynamics. The net result of these, imply differences in the seasonal flux for NO2. Here we perform the first-ever high-resolution measurements of NO2 exchanged between the atmosphere and a grazed African savannah landscape from 2015-2020. We use micrometeorological eddy covariance techniques with a quantum cascade laser (QCL) instrument to quantify the NO2 flux and explore temporal trends at diurnal, monthly, annual and interannual scales. Initial findings highlight the variation in NO2 flux with notable interannual change observed at monthly and hourly scale. Seasonal variation in NO2 flux is strongly linked to the onset of the rainfall season. Diurnal trends indicate maximum NO2 flux during daylight hours, with consistently low flux during night-time. These findings contribute to our understanding of near-surface atmospheric NO2 dynamics in arid landscapes and highlights the importance of shedding light on African atmospheric pollution.

 

172 Verification of an earth system model CCAM using the ground-based measurements across South Africa.

Poster

Nolusindiso Ndara1*, Jessica Steinkopf2, Amukelani Maluleke1, Gregor Feig1, Francois Engelbrecht2

1South African Environmental Observation Network, Pretoria, South Africa. 2University of the Witwatersrand, Johannesburg, South Africa

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Earth System models (ESMs) are global climate models with the capability to explicitly represent biogeochemical processes that interact with the physical climate and so alter its response to forcing such as those associated with human-caused emissions of greenhouse gases. Several ESMs exist such as Conformal cubic atmospheric model (CCAM), Community Atmosphere Biosphere Land Exchange (CABLE), Inline ocean model in CCAM and GCI Ocean model (WPOM-Wits Planetary Ocean Model). The limited verification of these models in Africa is a cause for concern and may result in the development of significant biases in the representation of the modelled processes. This study presents the verification of CCAM using ground-based measurements collected in different South African biomes. CCAM is a variable-resolution global atmospheric model that employs semi-implicit, semi-Langrangian methods to solve hydrostatic primitive equations. Data to verify the model representation of significant exchanges between the land surface and atmosphere, including the carbon, energy and water fluxes was obtained from six different EFTEON flux tower sites in South Africa representing a range of Biomes and environmental settings for the period 2020 – 2023. Using the selected variables, the model will be run hourly for the period of 4 years.  The successful verification of ESMs would enable the confident use of them in combination with the in-situ observations to identify hotspots of land-atmosphere fluxes and improve the development of the model processes and representations. This study forms part of the KADI project and will inform the development of climate services provision on the African continent.  

 

173 Review of existing research infrastructures and design of a concept for pan African research infrastructure

Poster

Nolusindiso Ndara1*, Marisa Gonzalez2, Rebecca Garland2, Gregor Feig1

1South African Environmental Observation Network, Pretoria, South Africa. 2University of Pretoria, Pretoria, South Africa

Session 13. In situ data for climate and other environmental services and policy support

Long-term research is critical to address the national research questions which cannot be tackled in the framework of single and time limited projects. Research infrastructures (RIs) enable the understanding of the drivers and patterns of environmental change through long term, collaboration and multidisciplinary research. However, Africa has a limited number and sparse distribution of RIs; in particular for observations of carbon exchange, atmospheric composition, biodiversity, marine processes and human health and population demographics. This thus hinders the development of a comprehensive environmental observation system in Africa. As part of solving or mitigating this issue, the KADI project aims to improve the knowledge about climate change in Africa and develop tools to combat its negative impacts. The current study therefore forms part of this larger project and presents a design of a concept for a pan-African climate observation RI. EFTEON is one of the South African RIs hosted by SAEON that aims to provide knowledge on environmental processes and change including data for biogeochemistry, biodiversity, meteorology and hydrology research. However, similar RIs are needed across Africa. Data from RIs is crucial as it will aid to make informed decisions about climate change mitigation or adaptation measures.

 

174 Seasonal dynamics and temperature sensitivity (Q10) of soil respiration in Afromontane grasslands, Drakensberg, South Africa

Poster

Lindokuhle Xolani DLAMINI

SAEON-EFTEON, Pietermaritzburg, South Africa

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Soil respiration (Rs), a crucial biogeochemical process, is a major pathway for COemission from ecosystems. Due to its temperature dependence, Rs may increase with global warming, especially in mountainous regions. Afromontane grasslands in temperate high-rainfall regions of South Africa are huge reservoirs of soil organic carbon (SOC). These ecosystems evolved with fire, and fire-exclusion leads to native plant afforestation. This study investigated seasonal dynamics and Q10 of Rs to understand the impact of fire-exclusion-driven afforestation and aspect on SOC dynamics. Using the Cathedral Peak Research Catchments initiated in the 1940s, this study compared an afforested fire-excluded site to a periodically burnt grassland within the same south-facing catchment. Additionally, it compared the south-facing periodically burnt grassland to a north-facing biennially burnt grassland. Measurements were performed using an 8-chamber LI-8100A automated system (north-facing) and a monthly static chamber-based manual technique (all sites, approximately 3 years). Linear Mixed-Effects Models showed that these two methods were complementary and seasonal variability in Rs was higher during summer than in winter in all sites. This seasonal variability of Rwas influenced by fire, soil temperature, and moisture. The afforested site had less topsoil SOC stocks, more overall Rs, and double the Q10 compared to the periodically burnt grassland. While fire increased Rs in the first growing season, the cooler south-facing grassland still had lower Rs and Q10 compared to both the afforested site and the north-facing slope. While often neglected, this study suggests that aspect play a crucial role in biogeochemical cycling and Afromontane grassland shows greater potential for C sequestration than afforested systems.  

 

175 Insights into hyperparameter-optimisation for shallow artificial neural network used in Eddy Covariance CO2 flux data gap-filling

Poster

Alina Premrov1*, Jagadeesh Yeluripati2, Matthew Saunders1

1Botany Discipline, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland. 2Information and Computational Sciences Department, The James Hutton Institute, Aberdeen, Scotland, United Kingdom

Session 13. In situ data for climate and other environmental services and policy support

Many popular Eddy Covariance (EC) CO2 flux gap-filling methods can work well for the less disturbed ecosystems; however, their application can be challenging for some disturbed ecosystems [1], such as rehabilitated former cutaway-peatlands, which can have very heterogenous nature, represented by vegetation, bare peat and open water areas. Artificial neural networks (ANNs) are one of the well-known machine-learning approaches used for such tasks [1]. This study provides insights into hyperparameter-optimisation for shallow ANN applied via ‘neuralnet’ function in R [2], used to gap-fill the missing EC CO2 flux data. Shallow ANNs differ from deep ANNs as they have simpler structure and are thought to be less computationally costly. The study is using an ANN example from Premrov et al (2024)[3], which previously showed promising results in gap-filling the EC CO2 flux data from Cavemount Bog, a rehabilitated former Irish cutaway-peatland [3,4]. Presented will be insights, such as procedures used to find the optimal hidden-configuration, and the optimal threshold-value for the error-function partial derivatives assigned in the ‘neuralnet’ [2]. It is thought that these insights may be potentially useful to those who may wish to further investigate this method for similar gap-filling tasks.

Acknowledgements

The authors are grateful to the Irish Environmental Protection Agency (EPA) for funding the CO2PEAT project (2022-CE-1100) under the EPA Research Programme 2021-2030.

References

[1] Zhu, S., et. al. (2023). DOI: https://doi.org/10.1016/j.agrformet.2023.109365.

[2] Fritsch, S., et. al. (2019). URL: https://cran.r-project.org/web/packages/neuralnet/neuralnet.pdf.

[3] Premrov et al. (2024). URL: https://drive.google.com/file/d/1-mWr6CRrKXvSVmcLWnpmXosyF69uDyp2/view (page 67).

[4] Bord na Móna, (2021) URL: https://www.bnmpcas.ie/wp-content/uploads/sites/18/2021/05/AA%20Screening%20Cavemount_FINAL%20w-app.pdf.

 

176 Innovations in autonomous sensor and sampler technologies for ocean carbon measurements through the EU GEORGE project

Poster

Socratis Loucaides1*, Ute Schuster2, Matt Mowlem3, Kathareena Seelmann4, Melchor González Dávila5, Ivan Alonso6, Nadine Lanteri7

1National Oceanography Centre, Southampton, United Kingdom. 2University of Exeter, Exeter, United Kingdom. 3Clearwater Sensors Ltd., Southampton, United Kingdom. 44H-JENA Engineering, Jena, Germany. 5University of Las Palmas Gran Canaria, Las Palmas, Spain. 6OCEOMIC Marine Bio and Technology, Las Palmas, Spain. 7Ifremer, Brest, France

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

The EU project GEORGE addresses the capability gap in ERIC’s infrastructure to collect fit-for-purpose in situ measurements of carbonate system parameters including pH, TA, DIC and pCO2, to better characterise and understand inorganic carbon cycling in the ocean, its exchange with the atmosphere and monitor the rate of ocean acidification. A major focus of GEORGE is to advance the TRL (from 6 to 8-9) of novel sensors to enable integration with ERIC infrastructure including fixed platforms and small autonomous platforms such as profiling floats and gliders. Sensor technologies include Lab-on-Chip (LoC) sensors for in situ measurements of pH, Dissolved Inorganic Carbon and Total Alkalinity and infrared based technologies for ocean-atmosphere CO2 flux measurements. Significant effort is also focused on improving and optimizing commercial off the shelf sensors for integration on fast-moving platforms and enhancing long term measurement performance. Sensor measurement validation technologies including autonomous samplers, calibration systems and anti-fouling strategies are also being developed to ensure data quality over long unattended deployments at sea. This talk will provide an overview of these new developments including their capabilities and plans for their validation and testing.

 

177 Carbon dioxide, methane and carbon monoxide were observed over one-year at the tall tower of El Arenosillo station in Southwestern Europe

Poster

Jose Adame1*, Padilla Ruben2, Isidoro Gutierrez-Alvarez3,4, Jose A Bogeat5, Antonio Lopez5, Margarita Yela6

1Atmospheric Sounding Station. El Arenosillo. National Institute for Aerospace Technology (INTA)., Huelva, Spain. 2aAtmospheric Sounding Station. El Arenosillo. National Institute for Aerospace Technology (INTA)., Huelva, Spain. 3Integrated Sciences Department. University of Huelva., Huelva, Spain. 4cCenter for Natural Resources, Health and Environment (RENSMA). University of Huelva, Huelva, Spain. 5Centro de Experimentación de El Arenosillo (CEDEA). National Institute for Aerospace Technology (INTA)., Huelva, Spain. 6Dept. of Earth Observation and Space Science. National Institute for Aerospace Technology (INTA)., Torrejon de Ardoz, Spain

Session 2. Exchange of reactive gases and aerosols between the land surface and the atmosphere in natural and managed ecosystems

Carbon dioxide (CO2), methane (CH4), and carbon monoxide (CO) – were sampled at three heights (10 m, 50 m, and 100 m) from December 2021 to December 2022, at the El Arenosillo station. Hourly averages exhibited variability based on altitude, ranging from 418 ± 5 µmol mol-1 at 100 m to 422 ± 8 µmol mol-1 at 10 m for CO2. For CH4, the values fluctuated from 1999 ± 30 nmol mol-1 at 100 m to 1986 ± 25 nmol mol-1 at 10 m, and ~102 ± 19 nmol mol-1 for CO. Monthly cycles indicated a peak in January-February for both CH4 and CO, with the lowest in June. CO2 reached its minimum in August. These gases exhibited daily patterns, reaching their maximum between 5:00 and 10:00 UTC, while the minimum at 15:00-18:00 UTC. The daily variations are influenced by atmospheric stability, photochemical activity, and vegetation. Factors such as photosynthesis, plant and soil respiration, strongly modulated the CO2 gradient. In cold months, the CH4 gradient (12-27 x 10-2 µmol mol-1 m-1) is influenced by vertical stability and local emissions while CO exhibits negligible vertical gradients. The gradients of CO2 and CH4 presented divergent patterns; the 10-50 m gradient for CO2 was higher than that from 50-100 m, while in CH4, it showed the reverse. This behavior could suggest a shallower CO2 surface layer compared to CH4. Observations at 100 m identified peaks in CO and CH4 suggesting a connection to the presence of a forest fire plume and fugitive CH4 emissions.

 

178 Improving Estimates of Arctic Ocean CO2 Uptake with a new Machine Learning derived p(CO₂) product for the Arctic Ocean

Poster

Victoria Dutch1, Dorothee Bakker1, Peter Landschützer2, Alizée Roobaert2, Jan Kaiser1

1University of East Anglia, Norwich, United Kingdom. 2Flanders Marine Institute (VLIZ), Ostend, Belgium

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

The Arctic Ocean covers only 3 % of the Earth’s surface but contributes 5 - 14 % of the global ocean carbon sink. Sparse and unevenly distributed in situ sea surface observations of the partial pressure of carbon dioxide, p(CO2), hinder our understanding of the magnitude and the controlling mechanisms of this CO2 sink. To overcome these limitations, we adapt the Self-Organising Map–Feed-Forward Neural network (SOM-FFN) method of Landschützer et al. (2016) to construct a monthly 1° × 1° p(CO2) product from January 1991 to December 2022. We first divide the Arctic Ocean (herein defined as the region north of 55° N) into five biogeochemical provinces using the SOM, and then derive non-linear relationships between p(CO₂) observations and predictor variables (i.e., biogeochemical drivers) for each province using the FFN method. Our reconstructed Arctic p(CO2) product is then evaluated against additional p(CO2) observations, chiefly from SOCATv2023 and from independent timeseries stations. 

We then use this new p(CO₂) product to derive estimates of the air-sea CO₂ flux for the Arctic Ocean. In line with previous studies, we find the Arctic Ocean to be a sizeable CO2 sink, with the greatest sink strength in the marginal ice zone . However, the magnitude and seasonal variability of this sink depends on the treatment of sea ice cover in the flux calculation. Uncertainty in the overall flux magnitude is also caused by the choice of gas transfer coefficient, although this is less significant when assessing the magnitude of the Arctic Ocean carbon sink.

 

179 Overview of the terrestrial ecosystem soil database of ICOS ETC and perspectives

Poster

Bruna Winck1*, Nicolas Saby2, Sebastien Lafont3, Céline Ratie2, Claudy Jolivet2, Jean-Philippe Chenu2, Benjamin Loubet1

1INRAE-ECOSYS, Palaiseau, France. 2INRAE-INFOSOL, Orleans, France. 3INRAE-ISPA, Villenave-d&apos;Ornon, France

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The use of eddy covariance (EC) techniques is widely used to measure CO2 exchanges between the surface and the atmosphere, and is the approach chosen in ICOS to monitor 49 Class 1 and 2 terrestrial ecosystem sites. The EC technique accurately monitors the ecosystem’s state and CO2 fluxes. Together with carbon imports as organic fertiliser, carbon exports as harvest (including animal herbivory), and dissolved carbon leaching and losses or gains of C by erosion, these data allow us to compute the carbon balance of the site. Imports and exports data are monitored in ICOS, but not the C leaching and erosion. In ICOS, the carbon balance of terrestrial sites will also be monitored by measuring the soil carbon stock (over 1 m depth) evolution over time with a planned revisit of 5 to 10 years at each site. In 2024, around half of the ICOS sites have sampled soil, and around 20 sites have been analysed. The ICOS analysis at most sites provides the carbon and nitrogen stock evaluation with its uncertainty and variability with depth. The texture is also measured when not already known at each site. For some sites, historical soil sampling could be used to evaluate a soil stock change, with the additional difficulty that the sampling protocol has changed with time. An overview of the existing database and how it compares to European soil carbon maps is given.  One identified limitation in the current soil sampling scheme is the missing information on the soil carbon stability, which is key to understanding the long-term fate of carbon in soils.

 

180 MODELING PEATLAND CO2 AND CH4 EXCHANGE UNDER EXTREME WEATHER EVENTS

Poster

Ville Tuominen1*, Tiina Markkanen1, Sari Juutinen1, Liyang Liu2, Bhaskar Mitra3, Jagadeesh Yeluripati3, Pia Gottschalk4, Claudia Nielsen5, Aram Kalhori4, Annalea Lohila1, Tuula Aalto1

1Fininnish Meteorological Institute, Helsinki, Finland. 2Laboratoire des Sciences du Climat et de l&apos;Environnement/IPSL, Paris, France. 3James Hutton Institute, Aberdeen, United Kingdom. 4GFZ German Research Centre for Geosciences, Potsdam, Germany. 5Aarhus University, Aarhus, Denmark

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Extreme weather events can cause anomalies in CO2 and CH4 exchange in wetlands. As seen in long-term measurements, extreme seasons can change plant community distribution and move the wetland ecosystem to a different stable state. To study extreme events in current and future climate, process-based ecosystem models, validated by in-situ observations in ICOS and other sites, are used.  
   Reanalysis weather data, often used to force the models, describes the weather state interpolated in a grid with a few kilometer resolution using weather stations and climate models. However, this type of forcing data may not show all the extremes in full severity. In addition, ecosystem models have their own limitations of representing plant phenology and carbon exchange. These together limit the capability of modeling to represent CO2 and CH4 fluxes under extreme weather conditions and may introduce bias to annual estimates, especially in the future scenarios as the frequency of extreme weather events is expected to increase in the future due to the climate change.
   Here we study how two different reanalysis weather datasets (CERRA and CRU-JRA) portray the observed extreme weather events in over 20 pristine and rewetted wetland sites across Europe. Furthermore, the performance of three ecosystem models (JSBACH-HIMMELI, ORCHIDEE-PEAT and DNDC) is compared to in-situ soil biophysical, carbon dioxide and methane measurements. Our aim is to supplement the current IPCC Emission Factors by defining the variability of emissions in current and future climate conditions. This supports the creation of Tier 3 Emission Factors for wetlands.

 

181 Continuous measurements of O2:CO2 flux exchange ratios above a cropland in central Germany

Oral

Christian Markwitz1, Edgar Tunsch1, Andrew C Manning2, Penelope A Pickers2, Alexander Knohl1

1University of Göttingen, Göttingen, Germany. 2University of East Anglia, Norwich, United Kingdom

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

The O2:COexchange ratio of land-atmosphere fluxes (ER) can be used to identify sources and sinks of CO2 in land ecosystems. During photosynthesis, the ER at the leaf level is approximately -1 mol mol⁻1, reflecting the uptake of one mole of CO2 associated with the release of one mole of O2. However, the ER at the level of entire ecosystems is largely unknown.

Here we present a unique dataset of one year of continuous O2 and CO2 flux measurements at the agricultural FLUXNET site Reinshof (51°29&apos;24.0"N, 9°55&apos;55.2"E) near Göttingen, Germany in 2023. Fluxes were calculated using flux-gradient approaches with air sampled from three inlets situated at 0.5, 1.0 and 3.0 m above ground. Dry mole fractions of O2 and CO2 were measured using a modified Oxzilla II differential oxygen analyzer (Sable Systems, USA) and a Li-840 (LiCor Biosciences, USA), respectively.

The results show that O2 and CO2 mole fractions and net O2 and CO2 fluxes were strongly anticorrelated. The ER shows a distinct diel cycle with less negative values during night but also higher uncertainty as well as an annual cycle, with values around -1.5 mol mol⁻under bare soil conditions and -1.1 mol mol⁻during the growing season. An influence from anthropogenic emissions was observed during the winter with stable atmospheric stratification when winds originated from the city centre. In conclusion, the ER of a cropland showed considerable diel and seasonal variability offering the opportunity to use O2 flux measurements as a tracer of the carbon cycle.

 

182 Recent developments in measuring XCO2, XCH4, and XCO using COCCON spectrometers and their relatives

Oral

Andre Butz1,2,3*, Benedikt Löw1, Ralph Kleinschek1, Sanam Vardag1,2, Vincent Enders1, Lukas Weis1, Silke Hoffmann1, Frank Hase4, Astrid Müller5, Matthias Max Frey5, Isamu Morino5, Hiroshi Tanimoto5, Jia Chen6, Thorsten Warneke7

1Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany. 2Heidelberg Center for the Environment (HCE), Heidelberg University, Heidelberg, Germany. 3Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany. 4Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research (IMK-ASF), Karlsruhe, Germany. 5National Institute for Environmental Studies (NIES), Tsukuba, Japan. 6Environmental Sensing and Modeling, Technical University of Munich (TUM), Munich, Germany. 7Institute of Environmental Physics, University of Bremen, Bremen, Germany

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

Ground-based sun-viewing measurements of the column-average dry-air mole fractions of carbon dioxide (XCO2), methane (XCH4) and carbon monoxide (XCO) are collected through the networks TCCON and COCCON to validate the respective satellite observations as well as atmospheric model performance. The portable and versatile COCCON Fourier Transform Spectrometers (FTS) also enable new observation concepts ranging from mobile deployments to explorative setups using scattered instead of direct sunlight. 

Here, we showcase recent developments in exploring new applications for the COCCON FTS. We report on the deployment of a mobile FTS on a cargo vessel commuting along the southern coastline of Japan to detect the outflow of hotspot emission sources. Further, we highlight the development of an FTS variant suitable for measuring ground-scattered sunlight. We positioned such a portable instrument side-by-side with the stationary CLARS-FTS (California Laboratory for Atmospheric Remote Sensing-FTS) on a mountain observatory above the Los Angeles basin and demonstrated the performance of our portable setup. Finally, we discuss an upcoming collaborative effort of the German COCCON community to deploy several instruments throughout Germany to detect gradients of XCO2, XCH4, and XCO on national, regional, and local scales supporting the national monitoring capacity ITMS (Integrated Greenhouse Gas Monitoring System).

 

183 Science communication: opportunities between Vivaldi and the Museum of Knowledge

Oral

Alexander Knohl1*, Franziska Koebsch1, Anne Klosterhalfen1, Christian Markwitz1, Ramona Dölling2, Karsten Heck2, Nina-Maria Knohl2, Sandra Potsch2, Antonius Adamske3, Mark Barden4

1University of Göttingen, Bioclimatology, Göttingen, Germany. 2University of Göttingen, Forum Wissen, Göttingen, Germany. 3Göttingen Baroque Orchestra, Göttingen, Germany. 4Detmold University of Music, Detmold, Germany

Session 15. Science communication and outreach to increase the impact of climate research

Communicating science to the wider public is not only about presenting scientific results, but also about explaining how research is done through the practices, perspectives and collaborations of researchers. Going beyond traditional science communication channels, for example by using museum exhibitions or music performances, offers exciting opportunities to share scientific work with a wider audience.

Here we present two case studies of science communication activities related to the ICOS ecosystem station Hainich (DE-Hai) in central Germany, which has been measuring CO2, H2O and energy exchange over an unmanaged old-growth forest for 25 years.

The special exhibition "Digital Forest" at the University of Göttingen&apos;s museum of knowledge Forum Wissen showcased a virtual reality installation that immersed visitors in the Hainich study site. Visitors virtually explored how drought conditions under a changing climate impact the exchange of CO2 and H2O, along with tree sap flux and forest structure. The exhibition was embedded in outreach activities with primary and secondary school pupils, workshops, guided tours and public policy debates. 

The science concert "Four seasons in (climate) change" was a collaboration between the University of Göttingen, the Göttingen Baroque Orchestra and the Detmold University of Music. In workshops, scientists and composers discussed the latest research on climate change. Inspired by the science, the composers recomposed Vivaldi&apos;s Four Seasons to reflect how climate change has altered the seasons expressed in the music.

Both activities were well received by the general public and stimulated intense discussions about climate change and its impact on forest ecosystems.

 

184 High emissions of CO2 and CH4 due to active-layer warming in Arctic tundra

Oral

Margaret Torn1,2*, Rose Abramoff3,4, Lydia Vaughn5, Oriana Chafe6, John Bryan Curtis7, Biao Zhu8

1Lawrence Berkeley National Laboratory, Berkeley, USA. 2University of California, Berkeley, Berkeley, USA. 3Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL, Gif-sur-Yvette, France. 4Ronin Institute, Montclair, USA. 5San Francisco Estuary Institute (SFEI), San Francisco, USA. 6University of Oregon, Eugene, USA. 7Eagle River Water & Sanitation District, Vail, USA. 8Peking University, Beijing, China

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Climate warming is expected to accelerate decomposition of arctic soil carbon, but controlled experiments as deep as the whole active layer are lacking. We deployed a novel experiment using heating rods inserted to the depth of permafrost in Utqiagvik (previously Barrow), Alaska to warm the whole active layer by roughly 3.5oC and measured the impact on soil-atmosphere fluxes of CO2 and CH4. We found that the magnitude of warming predicted to occur this century increased ecosystem respiration by ~30%, a temperature sensitivity (apparent Q10 of 2.8; n=79) much higher than that reported by experiments that warmed only the surface, and higher than the decomposition Q10 of 1.9-2 in most IPCC land models. A controlled shoulder-season warming experiment revealed that rapid melt of snow and ice, events which are becoming more common from rain-on-snow, can result in large emissions of methane that would otherwise be oxidized to CO2 before emission. Thus, warming promotes greenhouse gas emissions from the deepening active layer and longer talik (thawed layer under a frozen surface) season, portends arctic amplification of climate change.

 

185 A Review of Open Fire GHG Emissions in the Mediterranean Region Across Major Inventories

Poster

Rabia Ali Hundal1,2,3*, Saurabh Annadate1,2,3, Paolo Cristofanelli3, Michela Maione2,3, Rita Cesari4, Alessio Collalti5,6

1Scuola Superiore unversitaria Pavia (IUSS), Piazza della Vittoria 15, I-27100, pavia, Italy. 2University of Urbino, Urbino, Italy. 3Institute of Atmospheric Sciences and Climate, National Research Council, 40129, Bologna, Italy. 4Institute of Atmospheric Sciences and Climate, National Research Council, 73100, Lecce, Italy. 5National Research Council of Italy–Institute for Agriculture and Forestry Systems in the Mediterranean (CNR-ISAFOM), 06128, Perugia, Italy. 6National Biodiversity Future Center (NBFC), 90133, Palermo, Italy

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The increasing concern about greenhouse gas (GHG) emissions from open fires in the Mediterranean requires a thorough evaluation of the estimate approaches especially for carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and black carbon (BC). We analyzed emissions data from key inventories as CAMS, GFED and EDGAR (2003-2020 period). We found significant differences in emissions between datasets, mostly between GFED and CAMS, which account for both anthropogenic and natural fires, and EDGAR, which focuses only on anthropogenic fires from agriculture and waste burning (AWB).Differences are highlighted by contrasting estimates, with EDGAR’s AWB emissions for CO2 and CH4 in certain years exceeding GFED’ and CAMS’ ones. Results show continuous interannual variability with significant emission peaks in 2007, 2012, and 2017 corresponding with strong La Niña events, underlining the impact of climatic variability on wildfire activity. The major contributors to the emissions varied over time, with Italy, Algeria and Greece frequently dominating. Large differences for e.g. Italy, Algeria, and Greece, as well as uncertainties for France and Egypt, highlight the problems of accurately accounting for GHG emissions in these countries. For example, in 2012, GFED recognized 35% of CH4 emissions for Italy, while for CAMS Algeria was the highest with the same percentage. The difference in the data, particularly in the attribution of emissions to specific countries and the identification of top contributors, highlights the crucial need for consistent techniques based on atmospheric in situ observations to untangle discrepancies in the existing inventories. 

 

186 Assimilating Mid-Cost CO2 Sensor Measurements into WRF-Chem Eulerian and WRF-STILT Lagrangian Inverse Modeling for Quantifying CO2 Emissions in Paris

Oral

Jinghui Lian1,2*, Olivier Laurent2, Thomas Lauvaux3, Hervé Utard1, Grégoire Broquet2, Mali Chariot2, Michel Ramonet2, Hassan Bazzi4, Luc Lienhardt3, François-Marie Bréon2, Laurent Millair1, Philippe Ciais2

1Origins.earth, SUEZ Group, Paris La Défense Cedex, France. 2Laboratoire des Sciences du Climat et de l&apos;Environnement (LSCE), IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif sur Yvette Cedex, France. 3Groupe de Spectrométrie Moléculaire et Atmosphérique (GSMA), Université de Reims-Champagne Ardenne, UMR CNRS 7331, Reims, France. 4Université Paris-Saclay, AgroParisTech, INRAE, UMR 518 MIA Paris-Saclay, Palaiseau, France

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Since the early 2000s, many cities have pledged and implemented policies to achieve net-zero emissions by 2050. While most cities’ climate plans have been designed from inventories, new approaches relying on emission estimates from atmospheric observations are now being tested in several metropolitan areas. But to effectively monitor highly heterogeneous urban CO2 emissions using atmospheric observations, dense networks of CO2 sensors are needed, possibly with cost-effective sensors that have sufficient accuracy and precision. Here, we designed a mid-cost CO2 instrument for continuous atmospheric measurements in urban areas, targeting an accuracy of 1 ppm on an hourly basis. Since July 2020, nine mid-cost instruments have been deployed within Paris and its vicinity, remaining operational for over three years, with data coverage varying from 52% to 83% across stations. The data acquisition and calibration procedure have been automated by a newly implemented data processing system. Colocation periods with high-precision instruments show that mid-cost instruments achieve accuracies of 1.0 to 2.4 ppm for hourly afternoon data. We assimilate both mid-cost data and high-precision CO2 measurements into the WRF-Chem Eulerian and WRF-STILT Lagrangian inverse modeling systems, respectively. Our inversion framework also benefits from the use of an hourly fossil fuel CO2 emission inventory (Origins.earth) at a spatial resolution of 300 meters. Additionally, it utilizes biogenic fluxes derived from a modified VPRM model that integrates Sentinel-2 data and soil water content. This enables us to conduct a comparative analysis of different measurements and models, and to increase the robustness of quantifying CO2 emissions in Paris.

 

187 Urban Emission Assessment based on High-Resolution Dispersion Simulations and Bayesian Inversion

Poster

Junwei Li1*, Jia Chen1, Dominik Brunner2, Dietmar Öttl3, Maximilian May4, Sanam N. Vardag4, Andreas Luther1, Christopher Claus Holst5, Haoyue Tang1

1Environmental Sensing and Modelling, School of Computation, Information and Technology, Technical University of Munich, Munich, Germany. 2Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland. 3Air Quality Control, Regional Government of Styria, Graz, Austria. 4Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany. 5Institute of Meteorology and Climate Research Atmospheric Environmental Research, Karlsruhe Institute of Technology, Garmisch-Partenkirchen, Germany

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

City emission assessment is limited by the underlying model resolution if the model fails to reproduce the emission dispersion within urban terrains. Based on the ICOS Cities project, we established a high-resolution building scale modelling framework for Munich using the computational fluid dynamics (CFD) based model GRAMM-SCI/GRAL-ST-ROG for urban air dispersion simulation. In addition, Bayesian inversion was applied to refine estimates of urban emissions.

We used the GRAMM-SCI model to simulate mesoscale wind fields and take larger area wind situations into account by nesting simulation results at different domains and resolutions. GRAL-ST-ROG model then utilized these mesoscale wind fields to simulate the 10-meter spatial resolution wind field, which considered high-resolution land cover information, namely, topography, 3D building, and a self-developed tree cover dataset. To reduce the high computation demands of CFD, we only simulated 2880 selected wind situations and employ a newly developed Match-to-Observation (MTO) algorithm to match the simulated wind field to the wind observation data at each hour of the year. Doppler wind lidar vertical profile data are also used to validate and improve simulated wind fields. Based on Bayesian inversion framework, we optimize the annual total value and the temporal profile of emission inventories.

The development of the model so far focused on NOx simulations but is starting to be extended to CO2 simulations as first CO2 observation data become available in Munich. This study provides more detailed understanding of urban emissions and can help environmental management and policy-making to achieve respective environmental standards.

 

188 An autonomous in situ total alkalinity sensor

Poster

Allison Schaap*, Stathys Papadimitriou, Socratis Loucaides

National Oceanography Centre, Southampton, United Kingdom

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

Total alkalinity (TA) is one of the four measurable parameters used to characterize the oceanic carbonate system. TA data with higher spatial coverage and temporal frequency will contribute to better measurements, modelling, and understanding of the aquatic carbon cycle, providing insights into problems from global climate change to ecosystem functioning.  We present an autonomous sensor capable of providing this type of data via in situ TA measurements.

This sensor implements a single-point spectrophotometric titration TA assay and is based on a generic ocean chemical lab-on-chip hardware platform with fully integrated fluidic, optical, and electronic components.  The sensor samples seawater, adds in a titrant consisting of acid and pH indicator, degasses the resulting solution, and performs an optical measurement.  It can carry multiple calibration materials on board, allowing for routine re-calibration and quality checks in the field. The scientific applications of this sensor require reliable accuracy (~0.1%-0.5%) during deployments lasting months in harsh and varying conditions.  

This sensor has been tested and demonstrated both in the lab and in the field.   It has been deployed in several environments including a North Sea subsea carbon storage experiment, aquarium-grown and natural coral reefs, a Weddell Sea carbon uptake study, and an autonomous underwater vehicle.  The results from lab and sea trials show that the technology is in a strong position and regularly meets the scientific requirements for TA measurements. This presentation will highlight the development and evaluation of the instrument and show field data exemplifying its capabilities.

 

189 An effective machine learning approach for improving the global estimate of the land carbon sink

Oral

Félicien Meunier1*, Pascal Boeckx1, Marijn Bauters1, Stephen Sitch2, Hans Verbeeck1

1Ghent University, Ghent, Belgium. 2University of Exeter, Exeter, United Kingdom

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Ecosystems provide multiple services worldwide, e.g. storing tremendous amounts of carbon and mitigating global fossil fuel emissions thanks to photosynthesis. Present-day (and future) land carbon sinks are primarily estimated by land surface models (LSMs) which are mechanistic tools that simulate the processes occurring at the interface between the atmosphere and the biosphere. LSMs are therefore critical tools for understanding and predicting the dynamics of the land surface. However, LSMs have become increasingly complex and require heavy expert knowledge and computational tools to run. In this study, we showed that machine learning (black box) models could efficiently reproduce process-based (mechanistic) models. To do so, we trained gradient-boosted tree models (GBT models) with the outputs of TRENDYv12 that were initially generated to estimate the global land carbon sink. Data-driven models could successfully reproduce the long-term trends, the seasonality, and the spatial distribution of the global carbon sink and its components, with an average error (RMSE) of 10%. We then refined the global estimate of the land carbon sink by ranking and upscaling weighted averages of the individual TRENDYv12 model surrogates based on their capacity to reproduce fluxtower data from ICOS and other networks. As GBT models can also serve to make near-real time assessments of the carbon cycle of forests, we also investigated the contrasting impacts of last-year El-Nino on tropical forests: we show that the severe 2023/2024 drought in the Amazon caused the largest reduction of productivity in recent history, while the productivity of Congo Basin rainforests did not decline substantially. 

 

190 Methane exchange in the floodplain forest

Oral

Natalia Kowalska*

Global Change Research Institute CAS, Brno, Czech Republic

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

 

Floodplain forests play an important role in the exchange of methane (CH4) with the atmosphere. However, due to climate change and anthropogenic activities, main factors driving this exchange, such as ground water table and soil temperature, are constantly changing. The studied floodplain forest in Lanžhot, Czech Republic, represents nowadays relatively dry conditions.

The main aims of our study were to quantify the CH4 emission on the floodplain forest ecosystem level using the eddy covariance (EC) method, with special emphasis on environmental conditions, turbulence development and footprint, as well as to probe all potential CH4 sinks and sources within the studied ecosystem for arriving at a complete CH4 budget. The ecosystem-scale CH4 fluxes were analysed with regards to the CH4 emissions of water bodies within the EC footprint. CHfluxes from a stream located within the footprint of the EC tower were measured using floating chambers and bubble traps. Studies were complemented by the analysis of the contribution of trees to the CH4 exchange. For this purpose, stem chambers measured CH4 fluxes on hornbeam trees, one of the main tree species at the study site and in Central Europe. Additionally, CH4 fluxes from the soil were included in the analysis to capture all potential CHsources and sinks within the studied ecosystem.

We initially hypothesized that ecosystem-scale CH4 exchange will be negligible. Our results showed, however, that the whole ecosystem is a small but constant CH4 source.

 

191 Tracking methane emissions at the site-scale

Oral

Felix Vogel1*, Sebastien Ars1, Lawson Gillespie1,2, Timothy Khoo1,3, Siyar Urya3, John David Pomeroy4, Anthony Fabian1,5, Cassandra Worthy1, Meghan Flood1

1Environment and Climate Change Canada, Toronto, Canada. 2University of Toronto, Toronto, Canada. 3University of Waterloo, Waterloo, Canada. 4University of Guelph, Guelph, Canada. 5McMaster University, Hamilton, Canada

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

The Government of Canada has announced ambitious emission reduction targets for methane from the oil and gas sector of -75% and -45% for the waste sector by 2030 compared to 2020 levels. To date policy is solely based on emission reporting through inventories and industry-reporting, however, there is growing recognition that atmospheric observations can add important information to better constrain such estimates. In recent years, the subnational greenhouse gas monitoring team has deployed multiple platforms (vehicle-based, low-cost sensors, floating chamber) at different sites to quantify local methane enhancements, which were used in combination with modelling tools to derive emission estimate for industrial facilities (refineries, landfills, wastewater treatment plants) as well in natural areas (rivers, ponds). We will present results from the different campaigns, discussing how well atmospheric observations agree with existing reporting frameworks and what underlying drivers predict local methane emissions and their changes. We furthermore compare the results of different observational techniques from a yearlong deployment and measurements conducted during 41 controlled release experiments at a landfill site.

 

192 WMO IG3IS Integrated Global Greenhouse Gas Information System

Oral

Jocelyn Turnbull1,2*, Kimerbley Mueller3, Kevin Gurney4, Felix Vogel5, Bo Yao6, Timothy Hilton1, Alistair Manning7, Anita Ganesan8, Phil DeCola9, Oksana Tarasova10

1GNS Science, Lower Hutt, New Zealand. 2University of Colorado, Boulder, USA. 3NIST, Gaithersburg, USA. 4Northern Arizona University, Flagstaff, USA. 5Environment and Climate Change Canada, Toronto, Canada. 6China Meteorological Organisation, Beijing, China. 7Met Office, Exeter, United Kingdom. 8University of Bristol, Bristol, United Kingdom. 9University of Maryland, Washington DC, USA. 10World Meteorological Organisation, Geneva, Switzerland

Session 13. In situ data for climate and other environmental services and policy support

The WMO-sponsored Integrated Global Greenhouse Gas Information System (IG3IS) aims to further efforts to integrate activity-based emissions information with atmospheric observations  and modelling of greenhouse gasses.  Together these provide the best possible estimates of greenhouse gas emissions.  A critical component of IG3IS is to establish two-way linkages between scientific practitioners and stakeholders in the policy realm, tailoring the research actions to meet policy needs.  

To facilitate these efforts, IG3IS coordinates a variety of initiatives.  IG3IS leads the stakeholder engagement component of the recently initiated WMO Global Greenhouse Gas Watch (G3W) effort.   We host regular webinars and in-person Stakeholder Summits that bring together greenhouse gas scientists with policymakers and stakeholders.  We support establishment of new greenhouse gas observational networks and information systems through local feasibility studies, training events, summer schools and expert advice.  We work with other international organisations to achieve scientifically based greenhouse gas system development and stakeholder engagement.  An important effort is the establishment of good practice guidelines for greenhouse gas emissions information at the various scales of relevance to both researchers and policymakers.  In 2022, IG3IS released the first urban-scale good practice guidelines (WMO GAW Report 275), and are now drafting national-scale and forestry-scale guidelines along with a second edition of the urban-scale guidelines.   These guidelines can only be successful with strong community input and we will present current drafts of these documents and ways that the community can get involved.

 

193 Retrievals of CO2 and CH4 Maps from the EnMAP Satellite Using RemoTeC and Matched Filter

Poster

Leonie Olivia Scheidweiler1*, Ida Jandl2,3, André Butz1,4,5

1Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany. 2School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Melbourne, Australia. 3CSIRO Environment, Aspendale, Melbourne, Australia. 4Heidelberg Center for the Environment (HCE), Heidelberg University, Heidelberg, Germany. 5Interdisciplinary Center for Scientific Computing, Heidelberg University, Heidelberg, Germany

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

Satellite measurements are an important tool for the global monitoring of anthropogenic greenhouse gas emissions. While it is not a primary mission goal, the Environmental Mapping and Analysis Program (EnMAP) satellite is able to measure carbon dioxide and methane emission plumes from localized hotspot sources. We analyze observations of point and area sources of these gases taken by the EnMAP satellite, including a power plant in Riyadh, Saudi Arabia, an oil and gas facility in Turkmenistan, and the Pinto landfill in Madrid, Spain. We employ a physical retrieval (RemoTeC), which yields integrated column densities for the targeted greenhouse gas, and a statistical retrieval (matched filter), which outputs enhancements only, albeit being much faster and requiring less auxiliary data.
   First results indicate that the physical retrieval performs better at distinguishing surface albedo structures from the spectral signal of the target gas for some surfaces. The retrieved image contains a striping pattern caused by detector properties. The matched filter yields a smoother and destriped enhancement map, as it determines detector properties from the measurement statistics. It yields a lower total integrated mass enhancement for the emission plume than the physical retrieval. We aim to improve the retrieval tools, including by using the covariance matrix from the statistical retrieval as input information for the physical retrieval. A first analysis suggests that this combination method results in a smoothed and destriped image without sacrificing the accuracy of the physical retrieval.

 

194 Paris Mid-cost CO2 sensor network : performance assessment and suitability for city CO2 emission retrieval.

Poster

Olivier Laurent1*, Mali Chariot1, jinghui lian2, Herve Utard2, Michel Ramonet1

1LSCE, Gif sur Yvette, France. 2Origins.earth, SUEZ Group, Paris La Défense, France

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

A network of 26 Midcost CO2 sensors has been deployed at the roof level in the Paris urban and suburban area in the framework of the ICOS-Cities project. The purpose of such dense CO2 monitoring network is to feed an atmospheric inversion system for the quantification of CO2 emissions at the sub-city scale and/or discern specific sectors.

The presentation mainly deals with the sensor characterization and the appropriate calibration strategy. It focus on corresponding sensor performance in the field. Then it attempts to discuss the pertinence of such monitoring approach and its suitability for the city CO2 emission quantification.

 

195 Eddy Covariance measurements of CO2 fluxes at short and tall towers in the Paris area

Poster

Laura Bignotti1*, Jérémie Depuydt1, Pedro Henrique Herig Coimbra1, Alain Fortineau1, Anaïs Feron1, Carmen Kalalian1, Pauline Buysse2, Michel Ramonet3, Guillaume Nief3, Rainer Hilland4, Stavros Stagakis5, Andreas Christen4, Benjamin Loubet1

1ECOSYS, Université Paris-Saclay, INRAE, AgroParisTech, Palaiseau, France. 2INRAE-Institut Agro, UMR SAS, Rennes, France. 3LSCE, CEA, CNRS, Université Paris-Saclay, Ormes Les Merisiers, France. 4Environmental Meteorology, Institute of Earth and Environmental Sciences, University of Freiburg, Freiburg, Germany. 5Department of Environmental Sciences, University of Basel, Basel, Switzerland

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Cities are hotspots for greenhouse gas emissions, accounting for over 70% of global CO2 emissions (IEA, 2008). Accurate quantification of these emissions is crucial for developing and verifying effective mitigation strategies.

Within the ICOS Cities project, eddy covariance measurements of CO2 fluxes are currently running at two urban sites in Paris as part of a large pilot observatory for GHG emission estimation of the Paris region. The two sites, a short tower on a rooftop in the centre of Paris (Jussieu) and a tall tower on the NE periphery of the city (Romainville), exhibit different land cover composition within their footprint, with urban density decreasing from Jussieu to Romainville.

The analysis of one-year flux measurements (February 2023-January 2024) revealed seasonal variations in monthly diurnal patterns reflecting the interplay of anthropogenic and biogenic CO2 drivers at the two sites. 

During cooler months (October-March), anthropogenic emissions similarly dominated daily exchange patterns at both sites. Conversely, in May and June, only Jussieu displayed predominant CO2 emission during daylight hours, while Romainville showed traces of biogenic absorption, being closer to the diurnal CO2 flux patterns observed at ICOS ecosystem sites near Paris (FR-FON forest,FR-GRI crop). Throughout summer months (July-August), depopulation substantially decreased anthropogenic sources, resulting in slightly negative CO2 fluxes during daylight hours, even in Jussieu.

Weekends and weekdays patterns differed in Jussieu, showing an influence of people’s habits on diurnal fluxes in the city centre. This was not the case for Romainville, where more uniform flux cycles were observed throughout the week.   

 

196 Comparative Analysis of Prediction Models for CO2 Forecasting Across Diverse Ecosystems Using the ICOS Network

Poster

Pablo Catret Ruber1*, David García Rodríguez2, Ernesto López Baeza1,3, Domingo J. Iglesias Fuente4

1University of Valencia, Valencia, Spain. 2University Research Institute on Robotics and Information and Communication Technologies (IRTIC), University of Valencia, Paterna, Spain. 3Albavalor, Paterna, Spain. 4Valencian Institute of Agricultural Research (IVIA), Moncada, Spain

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The increasing trends of CO2 as a greenhouse gas are one of the strong threats to humankind, so that obtaining good forecasts of CO2 evolution is of crucial importance. In this study, a comparison of state-of-the-art prediction models for CO2 time series forecasting is made between over 30 CO2 measurement stations of the Integrated Carbon Observation System (ICOS). These stations correspond to different land covers and vegetation types. Furthermore, the stations are distributed across several climates of the Köppen Geiger climate classification. In the study, performance comparisons are made at each station between statistical, machine learning, deep learning, language models and mixed models. This work proves the usefulness of the data provided by ICOS, not only for studies of past behaviour but also as a solid basis for the development of forecasting models. The study provides model predictions with mean absolute percentage errors (MAPE) of less than 1% for daily observations one year ahead for over 20 stations and an error of less than 2% for all stations studied. Additionally, a comparative analysis of model performance at different measurement heights is carried out for the stations with available measurement heights.

 

197 A Near Real Time Framework for the Detection and Attribution of Carbon Flux Anomalies

Oral

Thomas Colligan1,2*, Colin Quinn1,2, Benjamin Poulter2, Eric Ward1,2, Brenden Fischer-Femal2

1University of Maryland, College Park, USA. 2NASA Goddard Space Flight Center, Greenbelt, USA

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Integrated greenhouse gas monitoring and verification systems require reliable information on surface-to-atmosphere fluxes of trace gases. In support of the US government&apos;s Greenhouse Gas Center (GHG), a workflow has been developed to provide near-real-time (NRT) land surface fluxes of carbon dioxide and methane and their uncertainties, using a cloud-based analysis framework. The flux products are generated via simulations of the LPJ-EOSIM dynamic global vegetation model, which has been used in the land surface ensembles for the Global Carbon and Methane Budgets of the Global Carbon Project for over a decade. Here, we extend the NRT framework to enable the rapid detection and quantification of the response of biospheric methane and carbon dioxide fluxes to extreme climate events on a global and regional scale. We discuss the mechanisms behind some of these regional anomalies and highlight long-term trends in increasing carbon flux anomalies with respect to the long-term mean. Our results demonstrate the need and value for more comprehensive monitoring and verification systems, along with fundamental research into the biospheric feedback loops driving the anomalies. 
 

198 Emissions of the oxides of nitrogen (N2O/HONO/NO) from fertilized soils

Poster

Syu-Ruei Jhang1*, Yo-Jin Shiau2, Yi-Ying Chen3, Charles C.-K. Chou3

1Department of Safety,Health and Environmental Engineering, National United University, Miaoli, Taiwan. 2Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, Taiwan. 3Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Nitrous oxide (N2O) is one of the mightiest greenhouse gas and HONO and NO play an important role in atmospheric photochemistry. However, the current situation of the emissions of the oxides of nitrogen (N2O/HONO/NO) is still remain unknown in Taiwan. In this study, field experiments were conducted to examine the emissions of oxides of nitrogen from two major crop types, which were determined by eddy covariance and gradient approaches. Our results revealed that oxides of nitrogen were significantly enhanced after soil fertilization and most of the estimated fluxes exhibited a clear diurnal patterns which were likely to be emitted during daytime, with a maximum value at noon (peak appearing at 11:00 to 12:00) and decreased at night. Seasonal variation in oxides of nitrogen emissions was significant across all treatments. Moreover, compare to upland crop (i.e., cabbages), oxides of nitrogen fluxes were performing a relative lower emissions during the wetland cultivation period, irrespective of N-fertilizer background. This implies that presence of fluxes emissions increased significantly during dry warmer seasons, but can be observed alleviated during cold seasons. Therefore, the impact of N-species emissions from the agricultural soil should focus on understanding the environmental drivers as well as field management (fertilization, irrigation, cropping systems etc.), as it can mitigate significant oxides of nitrogen emissions.

 

199 Five-year continuous measurements of CO₂ and CH₄ at the Atlas Mohammed V Atmospheric Research Station in Morocco.

Poster

Ibrahim Ouchen1*, Morgan Lopez2, Michel Ramonet2, Dro Tiemoko Touré3, Wahid Mellouki4

1Department of Geomorphology and Geomatics, Scientific Institute, Mohammed V University in Rabat, Rabat, Morocco. 2Laboratoire des Sciences du Climat et de l’Environnement (LSCE), IPSL, CEA-CNRS UVSQ, Université Paris-Saclay, Orme des Merisiers, Paris, France. 3Laboratory of Atmosphere Physic and Mechanic Fluids (LAPA-MF), University Felix Houphouet-Boigny, UFR SSMT, Abidjan, Ivory Coast, Abidjan, Côte d&apos;Ivoire. 4Institut de Combustion Aérothermique, Réactivité et Environnement, Centre National de la Recherche Scientifique (ICARE-CNRS), Orleans, France

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

An analysis of the long-term trends and temporal variations of the primary greenhouse gases (CO2, CH4) was conducted at the Atlas Mohammed V atmospheric research station in Northwest Africa. This study employed a complex sample setup and a Cavity Ring Down Spectrometer (Picarro G2301) from the Atlas Mohammed V atmospheric research station in North West Africa (33.4018N; 5.10489E). The measured mean values of CO2 and CH4 are 415.85 ± 0.25 (ppm) and 1947.26 ± 2.18 (ppb) respectively, which is correlated with the global concentration observations. The mean annual growth rates of CH4 (15.73 ± 3.23) ppb and CO2 (2.75 ± 0.24) ppm) closely align with the prevalent worldwide patterns. At the daily scale, the seasonal variation of CO2 does not exhibit any strong trends, except for a slight decrease during the daytime. However, for CH4, a significant increase is observed towards the end of the day. The concentration variations of both gases display significant seasonality, with peaks occurring during the spring and winter for the two gases, and minimum observed throughout the summer period spanning from June to September. Special focus was placed on the data collected during the intense Atlas 2019 campaign in Morocco, where the AMV station played a key role. Deploying an EM27/SUN instrument from September 17 to October 14, 2019, to measure the total column of XCO2, XCH4, and XCO. The data set generated during the Atlas campaign underscores the AMV station&apos;s ability to carry out continuous, long-term observations.

 

200 Intense transport of biomass burning products to the tropical Andes as witnessed by a unique station in Southern America

Poster

Laura Ticona1*, Marcos Andrade1, Michel Ramonet2, Olivier Laurent2, Fernando Velarde1, Mónica Pozadas1, Isabel Moreno1, Morgan Lopez2, Benoît Macquart2, Luis Blacutt1, Decker Guzmán1, Paolo Laj3

1Laboratory for Atmospheric Physics, Physics Research Institute, Universidad Mayor de San Andrés, La Paz, Bolivia, Plurinational State of. 2Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, 91191, Gif-sur-Yvette, France. 3Univ. Grenoble-Alpes, CNRS, IRD, Grenoble-INP, IGE, 38000, Grenoble, France

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

The 2023 Amazon fire season witnessed a record number of wildfires, likely exacerbated by the ongoing drought and the positive phase of ENSO. The lack of rain, and the consistently high temperatures, created conditions that allowed wildfires, usually man-made, to spread rapidly across the region. Bolivian Amazonia, covering 11% of the Amazon basin, was severely affected, with 180,000 hectares of forest burned by November. The smoke traveled long distances, affecting the air quality of large regions in the country, including some in the western highlands in the tropical Andes. During this period, the Chacaltaya GAW station (CHC, 16.3ºS, 68.1ºW, 5240 m a.s.l.), the highest in the world of this type, conducted measurements of atmospheric concentrations of greenhouse gases (CO2, CH4), reactive gases (CO, O3, SO2), and aerosols (eBC). This station, strategically located on the eastern branch of the Andean Cordillera, allows sampling air masses from the Altiplano, Amazon forest, Pacific Ocean, and the La Paz/El Alto urban area (~2 million inhabitants). In addition, measurements of the total atmospheric column abundance of CO2, CH4, CO, and H2O were made by the EM27/SUN FTIR spectrometer, installed in El Alto city (4100 m a.s.l.), the first of its kind in the Andean region. This work aims to analyze the concentrations of the surface GHG measurements, relying on other variables and analysis of back-trajectories for this purpose. Furthermore, it explores the relationship among satellite data (TROPOMI), the CAMS high-resolution forecast model, and ground-based measurements.

 

201 CarbonBridge - Connecting GHG satellite measurements with ground based measurements through vertical profiles.

Oral

Colm Sweeney1*, Britton Stevens2, Bianca Baier3, Kathryn McKain3, Jeff Peischl3

1Boulder, Boulder, USA. 2NCAR, Boulder, USA. 3NOAA, Boulder, USA

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

For several decades, aircraft, and now balloon, vertical profiles of greenhouse gases (GHGs) have provided a critical constraint for satellite retrievals, forward and inverse models, and for our basic understanding of the carbon cycle and GHG budgets. Despite the powerful constraint that vertical profiles provide, planned campaigns and routine profiling programs are globally sparse and insufficient, given the challenges of interpreting remote sensing measurements that depend on significant bias corrections and uncertain transport models.

Recent global aircraft campaigns, commercial aircraft measurements, routine light aircraft sampling, and balloon-based platforms provide us with robust measurement technologies that enable an operational, instead of research-based, approach for capturing profiles of GHGs. However, it will require significant effort and international collaboration to achieve the spatial and temporal coverage needed to bridge between surface and spaceborne GHG observations.  We propose a multi-national, multi-institutional and multi-platform approach, which seeks to use regular measurement campaigns,  routine sampling from flights of opportunity on high-use (e.g. commercial and government) aircraft, and operational balloon sites. The resulting network will enable validation of satellite measurements, improved understanding of variability in GHGs throughout the troposphere and better understanding of the role that vertical mixing has in vertically distributing GHGs. It is important that the global community recognizes this opportunity and acts together to leverage these new possibilities. 

 

202 Tussock Tundra CH4 Fluxes are Heterogeneous and Sensitive to Spring Conditions: An NGEE-Arctic Study at Council, Alaska

Poster

Sigrid Dengel*, Margaret Torn

Lawrence Berkeley National Laboratory, Berkeley, USA

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Arctic tussock tundra is often treated as one plant community for modeling and projecting greenhouse gas fluxes, but fine-scale heterogeneity in thaw, and thus hydrology, can have large impacts on greenhouse gas fluxes. We measured CH4 exchange and ecosystem properties between 2017-2023 near Council, Alaska (AmeriFlux site US-NGC), as part of the Next Generation Ecosystem Experiment (NGEE-Arctic). The flux tower’s northern footprint was moderately dry while the southern section contained inundated thermokarst features with different thaw depth, soil moisture, and temperature. Soil thawed earlier in spring in the non-thermokarst areas, but by July thermokarst features had a thaw depth of 1 m almost a month before those in the drier, upland areas. While there was little interannual variation in meteorological conditions in summer, variation in spring conditions dictated CH4 fluxes at the site. The highest CH4 fluxes occurred in 2019 [growing season average 20.1 nmol m-2s-1], which had a mild, wet spring (snowmelt 24 May). The lowest fluxes were in 2022 [growing season average 5.8 nmol m-2s-1], when spring was cooler and drier (snowmelt 29 April). In all years, the influence of thermokarst methane hot spots was clear in footprint-averaged fluxes. The tundra had heterogeneous CO2 and CH4 fluxes, in space, seasonally, and interannually. These were associated with wetland plants (model plant functional type under development) and with thermokarst and weather impacts on snow and subsurface moisture and temperature, pointing to the need for better representation of thermo-hydrology in land models.

 

203 Source attribution, scaling properties, and intensities of fossil fuel Scope 1 and Scope 2 CO2 emissions from all US cities

Poster

kevin gurney1*, Pawlok Dass1, Jose Lobo2, Shade Shutters2, anna kato1

1Northern Arizona University, Flagstaff, USA. 2Arizona State University, Tempe, USA

Session 12. Translating Scientific CO2 Emission Research into City Services

The Vulcan Project version 4.0 emissions data product has generated all fossil fuel CO2 emissions for the US landscape, every hour, from 2010-2021 down to the scale of neighborhoods. From this complex landscape, we have extracted FFCO2 emissions for every urban area, following multiple commonly used urban definitions. The information extracted includes both Scope 1 and Scope 2 emissions plus the newly produced anthropogenic heat with a wide array of “functional” attributes such as sector, fuel, vehicle class, building class, road class, and industrial sub-sector. Here, we analyze ~4000 US cities in terms of their source composition, typology (e.g., consumer versus producer), intensities (e.g., per capita, per floor area), and scaling properties. In particular, urban scaling properties provide novel insight into emergent properties such as the relationship between urban metabolism and urban size properties. These properties including the generation of a series of comparative metrics offers cities tools to both understand their emitting landscape and build a suite of “peer” cities to explore mitigation learning.

 

204 Assessment of the Climate Trace global powerplant CO2 emissions

Poster

kevin gurney1*, Pawlok Dass2, Bilal Aslam2, Lech Gawuc2, anna kato2

1northern Arizona University, Flagstaff, USA. 2Northern Arizona University, Flagstaff, USA

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

Accurate estimation of planetary greenhouse gas emissions at the scale of individual emitting activities is a critical need for both scientific and policy applications. Powerplants represent the single largest and most concentrated form of global GHG emissions. Climate Trace, co-founded and promoted by former Vice President Al Gore, is a new effort using, in part, artificial intelligence (AI) approaches to estimate asset-scale GHG emissions. Climate Trace recently released a database of global powerplant CO2 emissions at the facility-scale that uses both AI and non-AI estimation approaches. However, no independent peer-reviewed assessment has been made of this important global emissions database. Here, we compare the Climate Trace powerplant CO2 emissions to an atmospherically calibrated, multi-constraint estimate of powerplant CO2 emissions in the United States. The 3.7% (65) of compared facilities that used an AI-based approach show a mean relative difference of -1.1% (SD: 46.4%) in the year 2019. The 96.3% (1682) of the facilities that used a non-AI-based approach show a mean relative difference of -49.4% (SD: 117.7%). Of the non-AI estimated facilities, 150 (8.9%) facilities agree to within ±20%. The large differences between Climate Trace and Vulcan-power emission estimates for these facilities is primarily caused by Climate Trace’ use of a national-mean power plant capacity factor (CF) which poorly represents the reported power plant capacity factors of individual US facilities and leads to very large errors at those same 1682 facilities.

 

205 Investigation of CO2 sources, variability and trends in Mexico City

Oral

Michel Grutter1*, Michel Ramonet2, Thomas Lauvaux3, Ke Che2, Noemie Taquet1, Wolfgang Stremme1, Carlos Alberti4, Victor Almanza1, Alejandro Bezanilla1, Phillipe Ciais2, Agustín García-Reynoso1, Eugenia González1, Frank Hase4, Oliver Laurent2, Morgan Lopez2, Yi Liu3, Sandra Porras1, Yang Xu2

1Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico. 2Laboratoire des Sciences du Climat et de l’Environnement (LSCE), Paris, France. 3Université de Reims-Champagne Ardenne, Reims, France. 4Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

Efforts to reduce CO2 emissions from large urban centers, such as the Mexico City Metropolitan Area (MCMA) with its >22M inhabitants, will be crucial in reaching the needed goals for minimizing the impacts of climate change. Column-integrated concentrations of GHG have been performed in and around the city since 2012 with FTIR solar-tracking spectrometers, and an intensive field campaign (MERCI-CO2) that included 7 FTIR systems was carried out in 2020/21, as part of a fruitful French-Mexican collaboration, complementing the 2 in situ analyzers operated continuously in urban and background sites. A modeling system that includes inputs from weather parameters, local and global inventories and biogenic flux estimates was implemented. Data from ground observations and satellite instruments have been assimilated to quantify, with an analytical Bayesian technique, the emissions of CO2 in the MCMA. Results from our comparison between the simulated and observed concentrations and the urban-rural gradients obtained from OCO-3, FTIR ground-based and surface in-situ observations, as well as the corrected emissions after the inversion, will be presented. Independent studies using long-term FTIR data show that the CO/CO2 and HCl/CO2 ratios can be valuable parameters to estimate CO2 emissions from urban activities and volcanic emissions, respectively. We show how a detailed time- and space-resolved study linking observations to surface fluxes has the potential not only to improve our knowledge of the source’s magnitude and distribution, but also to capture the changes over time produced by extraordinary events (COVID-19, ENSO, etc.) and by the actions to reduce the emissions.

 

206 Quantifying the Total Water Available to trees through water fluxes measurements at 14 European forest sites

Poster

Nicolas Delpierre1,2*, Emilie Joetzjer3, Sébastien Lafont4, Daniel Berveiller5, Simon Carrière6, Arsène Druel7, Christophe François5, Nicolas Martin7, Guillaume Simioni7, Jean-Marc Limousin8

1Laboratoire ESE, Université Paris-Saclay, Gif-sur-Yvette, France. 2Institut Universitaire de France, Paris, France. 3UMR Silva, INRAE, Champenoux, France. 4UMR ISPA, INRAE, Villenave d&apos;Ornon, France. 5Laboratoire ESE, CNRS, Gif-sur-Yvette, France. 6UME METIS, Sorbonne Université, Paris, France. 7URFM, INRAE, Avignon, France. 8CEFE, CNRS, Montpellier, France

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Historically, eddy covariance (EC) measurements have been widely used to quantify the Net Ecosystem Productivity, i.e. the carbon balance, of ecosystems. Less attention has been paid to EC measurements of water vapour fluxes which quantify the Actual Evapotranspiration (AET). The latter have been used to assess the closure of the energy balance, or to estimate canopy conductance, but rarely to establish a water balance. Here we use AET and precipitation measurements to calculate the cumulative water deficit (CWD), i.e. the running difference between AET and precipitation, at 14 ICOS forest sites over the period 2016-2023. A negative CWD value indicates that water has been mobilised from the soil by the trees to ensure their transpiration. In case of strong drought, the maximum CWD value quantifies the total water extractable from the soil by trees, that we term the Total Available Water (TAW, in mm). TAW is a critical parameter in ecosystem and land surface models. We quantify TAW to reach 230 ± 115 mm at the 14 ICOS forest sites studied. In most sites, this is more than two times the soil water holding capacity calculated from pedotransfer functions applied to soil characteristics compiled in the European Soil Data Center (ESDAC). We discuss the implications of these new TAW estimates on the parameterization of ecosystem and land surface models used to simulate the water and carbon balances of forests.

 

207 Low CH4 emission level by Eddy Covariance observation in water-efficient paddy Rice practices in central Taiwan

Poster

Charles C.-K. Chou*, Yu-Ting Shih, Yi-Ying Chen, Chian-Yi Liu

Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Paddy rice, a key food and economic crop in East Asia, has been under scrutiny due to methane (CH4) emissions during flooding, a concern highlighted at COP28. To address this, water-efficient methods like spike-watering are being promoted. This study, conducted from February to June 2023 in Taichung City, Taiwan, examined CO2 and CH4 emissions, filled missing data, and calculated the carbon budget using the eddy covariance method. The findings revealed that CH4 flux is more heat-dependent during flooding but remains relatively stable with wind variations. Wind, however, is a significant factor during spike irrigation. The carbon budget showed a CO2 sink of -17,634 kg-CO2 per hectare, comparable to the carbon sequestered after rice harvest (16.5 tons CO2 equivalent). The net CO2 sinks were -6,573 kg-CO2 per hectare, with a CH4 emission of 21.4 kg-CH4 per hectare (equivalent to 1,647.8 kg-CO2). Given these results, CH4 emissions cannot be overlooked when considering the carbon sink and its components. The study found that CH4 emissions peak (0.04 μmol/m2/s) during flooding and field drying, both of which are water management-related. However, in water-efficient operations, CH4 levels are low according to some paddy rice reports. Therefore, water-efficient practices not only conserve water but also reduce CH4 emissions. Peak phases among GHGs, CH4, CO2, and latent heat fluxes, were analisied to understanding  the process of the surpressed CH4 emission in the field.

 

208 Revisit the theories for below-canopy eddy covariance measurements in a karst forest in southwest China

Poster

Hanshu Wang*, Jinshu Chi

HKUST(GZ), Guangzhou, China

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

The karst region occupies about 20% of the global terrestrial area and typically consists of complex and various carbon cycling processes. Because of the geomorphological and hydrogeological characteristics, it is still challenging to estimate the carbon budgets of the heterogeneous karst ecosystems. The below-canopy eddy covariance (EC) system can provide a unique opportunity to directly measure the net CO2 exchange between the forest floor and the atmosphere. However, due to a lack of theoretical understanding of the fluid dynamics in the trunk space, application of the below-canopy EC technique requires more profound theories especially for forests situated in a complex terrain, such as the karst forests.

In this study, we will revisit the micrometeorological theories for the below-canopy EC measurements based on mass conservation, footprint theories, turbulent structures and (co)spectra analyses. With these theoretical understandings and validations, we will present some preliminary results on the one-year EC flux data collected from our site located in a karst primary forest in southwest China. Our study will provide some insights into measuring the forest floor CO2 fluxes in a complex forest site using the below-canopy EC approach and a baseline estimate of the forest floor contribution to the karst forest carbon budget.

 

209 Net Ecosystem Productivity of a mature temperate deciduous oak forest: comparing flux and biometric estimates

Poster

Daniel Berveiller1, Alexandre Morfin1, Gaëlle Vincent1, Laure Barthes2, Stéphane Bazot2, Timothé Guillot2, Christophe François1, Kamel Soudani2, Nicolas Delpierre2,3

1Laboratoire ESE, CNRS, Gif-sur-Yvette, France. 2Laboratoire ESE, Université Paris-Saclay, Gif-sur-Yvette, France. 3Institut Universitaire de France, Paris, France

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

The eddy covariance (EC) technique provides an estimate of the net ecosystem productivity (NEP). Since its inception, questions have emerged regarding the ability of EC to accurately measure NEP. Here we compare NEP estimates of a mature, 150-yr old temperate oak forest (Fontainebleau-Barbeau, ICOS FR-Fon), established over 2007-2021. The NEP_EC of this 150-yr old forest is of 494±72 gC m-2 yr-1 (i.e. 6920 gC m-2 over 2007-2021), which places it in the high range of data for mature temperate deciduous forests. Over the same period, carbon stock increased by 3250 gC m-2 in woody tissues and 1440 gC m-2 in soil organic carbon. The biometric estimate of NEP in this forest thus reaches 67% (= (3250+1440)/6920) of NEP_EC. Reasons for this discrepancy may be : (1) the FR-Fon flux tower underestimates ecosystem respiration, as suggested by measurements of soil respiration and below-canopy EC fluxes, probably in relation to the site location at the edge of a plateau overlooking a river 50-m below ; (2) the fine root carbon stocks has increased and should be added to the biometric estimate of NEP. Our biometric estimate of NEP shows that though 80% of long-term carbon storage occurred in woody biomass, 20% ended in the accretion of the soil organic carbon stock. This is equivalent to 10 per mil increase of the SOC stock per year, coherent with trends reported for forest soils in France, Germany and Finland.

 

210 From Monoculture to Diversity: Spontaneous tree growth and carbon dynamics after Coniferous removal at a humid temperate forest site

Poster

Marius Schmidt1*, Alexander Graf1, Anna Hofer2, Laura Müller3, Michael Leuchner3, Gunnar Ketzler3, Partrizia Ney4, Clemens Drüe5, Harry Vereecken1, Thomas Pütz1

1Institute of Bio- and Geosciences: Agrosphere (IBG-3), Research Centre Jülich, Jülich, Germany. 2Water and Emvironmental Engineering, Faculty of Civil Engineering, RWTH Aachen University, Aachen, Germany. 3Physical Geography and Climatology, Institute of Geography, RWTH Aachen University, Aachen, Germany. 4Department of Safety and Radiation Protection, Environmental monitoring: Meteorology (S-UM), Research Centre Jülich, Jülich, Germany. 5Department of Environmental Meteorology, University of Trier, Trier, Germany

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

In September 2013, 8.6 hectares of Norway spruce (Picea abies) monoculture were cleared in the Eifel National Park, Germany, and left to spontaneous regrowth of the expected deciduous forest matching the site’s climate and soil conditions. The area is located within the 38.5 hectare experimental catchment “Wüstebach” (50° 30’N, 6° 19’E, 595 to 630 m a.s.l.), one of the core investigation sites of TERENO (TERrestrial ENvironmental Observatories, https://www.tereno.net). Here, the exchange of energy and matter fluxes between spruce forest and atmosphere were monitored by an ICOS-associated eddy-covariace tower (DE-RuW) since 2010. A second station was installed within the newly established clearcut in 2013. Due to game (boar and deer) pressure, 2 hectares of the clearcut were additionally fenced. Over the first ten growing periods (2014-2023), the area notably shifted from a CO2 source to a sink within eight years. The analysis focuses on the flux components, gross primary productivity, season length and peak fluxes and compares the spruce forest with the regrowth of the clearcut. Data on species, height, and diameter of regrowing trees, collected inside and outside the fence, show dominance by rowan (Sorbus aucuparia), propagated by birds, followed by wind-dispersed spruce and birch (Betula pendula). Rowan and birch grow twice as fast as spruce, with growth notably enhanced inside the fence, especially for rowan. This study provides rare insights into the dynamics of forest regeneration and the associated changes in carbon exchange.

 

211 A multifaceted approach for urban methane sources identification in Melbourne, Australia

Poster

Jhonathan Ramirez Gamboa*, Zoe M. Loh, Christopher G. R. Caldow, Nasimeh Shahrokhi, Cathy M. Trudinger, Elise-Andre Guerette, Ann Stavert, Ray Langenfelds, Blagoj Mitrevski, Darren Spencer, Christopher T. Roulston, Paul Krummel

CSIRO, Aspendale, Australia

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Methane (CH₄) is a potent greenhouse gas, and Australia&apos;s commitment to the Global Methane Pledge aims for a 30% reduction in emissions by 2030 (relative to 2020 levels). To achieve this ambitious goal, a deeper understanding of urban and regional methane sources is critical. Recent work highlighted the need for an improved emission inventory for Melbourne. Essential to this is the expansion of the urban observational network, to better detect emissions and attribute sources.

We have recently increased the density of our in-situ network (from one site to four) and deployed methane isotope analysers at three key locations. These will be used to characterise emission plumes from potential large emission sources including water treatment plants and oil and gas refineries.

Besides expanding the in situ observation network our approach includes complementary mobile surveys targeting major known methane sources. These surveys utilise isotopic signatures and ethane measurements to refine source attribution. Alongside this, flask sampling for further discriminating tracers, such as nitrous oxide (N2O) and synthetic greenhouse gases, will be deployed to identify emissions from wastewater treatment and landfills. This strategy provides a rich data set for source characterization and attribution. Additionally, analysis of historical observations of methane and other tracers measured at our primary site over the last decade will offer insights into how local emission sources have changed over time.

Here we present preliminary results of the network expansion, mobile surveys, and tracer exploration approaches to improve our understanding of urban methane in Melbourne, Australia.

 

212 Data-driven modeling of carbon fluxes across the Arctic-boreal region: recent achievements and future opportunities

Poster

Anna-Maria Virkkala1,2*, McKenzie Kuhn1, Jacob Nelson3, Olli Peltola4, Gerard Rocher-Ros5, Sophia Walther3, Kyle Arndt1, Annett Bartsch6, David Bastviken7, Grant Falvo8, Alexandra Hamm2, Joshua Hashemi9, Ludda Ludwig10, David Olefeldt11, Martijn Pallandt2, Frans-Jan Parmentier12, Edward A. G. Schuur13, Claire Treat9, Judith Vogt3, Carolina Voigt14, Jennifer D Watts1, Isabel Wargowsky1, Birgit Wild2, Yili Yang1, Amanda H. Armstrong15, Logan Berner13, Valeria Briones1, Mathias Göeckede3, Elchin Jafarov1, Susan M. Natali1, Kathleen Ornldahl13, Benjamin Poulter15, Brendan M. Rogers1, Gustaf Hugelius2

1Woodwell Climate Research Center, Falmouth, USA. 2Stockholm University, Stockholm, Sweden. 3Max Planck Institute Biogeochemistry, Jena, Germany. 4Natural Resources Institute Finland, Helsinki, Finland. 5Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden. 6b.geos GmbH, Korneuburg, Austria. 7Department of Thematic Studies - Environmental Change, Linköping University, Linköping, Sweden. 8Department of Plant, Soil and Microbial Sciences, Michigan State University, Michigan, USA. 9Alfred Wegener Institute, Potsdam, Germany. 10Department of Earth and Environmental Science, Columbia University, New York, USA. 11University of Alberta, Edmonton, Canada. 12Centre for Biogeochemistry in the Anthropocene, Department of Geosciences, Oslo, Norway. 13Center for Ecosystem Science and Society, and Department of Biological Sciences, Northern Arizona University, Flagstaff, USA. 14University of Hamburg, Hamburg, Germany. 15University of Maryland Baltimore County - GESTAR 2, Baltimore, USA

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Arctic-boreal regions contain globally significant carbon reservoirs, which are vulnerable to release into the atmosphere due to climate change and permafrost thaw. However, despite intense measurements across Arctic-boreal ecosystems in the last decades, estimating carbon dioxide and methane budgets across the entire domain has remained a challenge. Recent flux synthesis efforts in combination with new remote sensing products, as well as statistical and machine learning models have opened novel approaches to increase our modeling capability and understanding of carbon dynamics. These data-driven modeling approaches capture complex relationships, often have a good predictive performance, and have a lower computational cost compared to other modeling approaches. Yet, carbon flux and geospatial predictor data describing processes related to wetland and aquatic ecosystems, permafrost, and disturbances are limited. Furthermore, due to the correlative nature of data-driven models (i.e., they are not based on mathematical functions of key processes), these models struggle with extrapolation. Consequently, modeled Arctic-boreal carbon budget estimates can vary significantly. For example, average terrestrial CO2 flux estimates of net ecosystem exchange for roughly 2001-2020 range between -1000 to -250 Tg C yr-1 and wetland CH4 emissions between 15 and 35 Tg CH4 yr-1. To reduce uncertainties in terrestrial and aquatic carbon budgets and improve global emissions targets, we present a review on recent advancements, remaining challenges, and novel insights of data-driven Arctic-boreal carbon flux modeling.

 

213 Urban-scale inversions of methane emissions for Melbourne, Australia

Oral

Nasimeh Shahrokhi1*, Cathy Trudinger1, Peter Rayner2, Zoe Loh1, Jhonathan Ramirez-Gamboa1, Christopher Caldow1, Paul Krummel1, Paul Fraser1, David Etheridge1, Bronwyn Dunse1, Ashok Luhar1

1CSIRO Environment, Aspendale, Australia. 2The Superpower Institute, Melbourne, Australia

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Understanding methane emissions is essential for prioritising mitigation efforts and tracking progress in emissions reduction. However, methane emissions remain highly uncertain, particularly in urban areas. Methane emissions from several sectors, including waste management, energy and nearby agriculture, give urban emissions a particularly complex spatial structure. In this study, we focus on methane emission estimates for Melbourne, Australia. There are no national gridded methane inventories for Australia, so we explored global datasets, including the Emissions Database for Global Atmospheric Research (EDGAR), to estimate prior emissions. We also distributed national emission estimates using regional information on landfills, wastewater treatment plants and livestock; this appears to give a better representation of emission patterns than the EDGAR dataset. 

To create more comprehensive and accurate emission inventories for Melbourne, observational data on methane mixing ratios in the region are essential. This study has initiated the expansion of the methane monitoring network in Melbourne, from one to four in-situ stations, complemented by drive-around surveys. We ran a chemical transport model forced with prior emissions and compared the resulting modelled mixing ratios with observations. The comparison suggests that further improvements are required to reduce the model mismatch with observations. We used a synthesis inversion to infer scaling factors for the different emission sectors from observations at the four stations. We also used a four-dimensional variational data assimilation inversion system to infer the spatial pattern of emissions. We will present results from these two inversion approaches

 

214 Building-resolved CO2 simulations to estimate emissions of the city of Zurich

Oral

Leonie Bernet*, Lionel Constantin, Lukas Emmenegger, Stuart K. Grange, Christoph Hüglin, Nikolai Ponomarev, Pascal Rubli, Dominik Brunner

Empa, Laboratory for Air Pollution / Environmental Technology, Dübendorf, Switzerland

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Urban areas significantly contribute to global greenhouse gas (GHG) emissions and play an important role in emission reduction strategies. Monitoring urban GHG emissions is therefore essential for optimizing mitigation efforts and supporting city climate action plans. The emissions are typically quantified using "bottom-up" annual emission inventories. Although this concept is well established, it should be complemented by an observation based "top-down" approach employing high-resolution models to trace measured concentrations back to their sources.  
   
   In Zurich, a city-wide monitoring network comprising around 80 sites with mid- or low-cost CO2 sensors was installed to test measurement setups and their role in the top-down evaluation of emissions. To simulate COconcentrations and transport, we use the building-resolved GRAMM-GRAL model system (Graz mesoscale and Lagrangian Model). Our COsimulations at 10 m resolution help to better understand COemissions and sinks in the city of Zurich.
   
   We compare the COsimulations with observations from the urban sensor network and evaluate the network&apos;s efficiency in capturing city-scale gradients, as well as the utility of the low-cost versus mid-cost sensors. Furthermore, we combine the observed COconcentrations with the model using a Bayesian inversion approach to trace measured concentrations back to the different emission sectors. This approach helps to verify and optimize the city&apos;s emission inventory and supports its path towards net-zero emissions by 2040.

 

215 The variability of terrestrial CO2 fluxes in semi-arid regions of the Southern hemisphere as seen by GOSAT

Oral

Sanam N. Vardag1,2*, Eva-Marie Metz1, Lukas Artelt1, Sourish Basu3,4, Martin Jung5, André Butz1,2,6

1Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany. 2Heidelberg Center for the Environment, Heidelberg University, Heidelberg, Germany. 3Goddard Space Flight Center, NASA, Greenbelt, Maryland, USA. 4Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, USA. 5Department of Biogeochemical Integration, Max Planck Institute for Biogeochemistry, Jena, Germany. 6Interdisciplinary Center for Scientific Computing, Heidelberg University, Heidelberg, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Terrestrial carbon fluxes in the southern hemisphere still exhibit large uncertainties due to limited in-situ measurements and a lack of comprehensive process understanding. Greenhouse Gases Observing Satellite (GOSAT) measurements of XCO2 can be used in an atmospheric inversion using the model TM5-4DVAR to obtain net CO2 fluxes in remote areas. To understand the drivers of the CO2 variability, Dynamic Global Vegetation Model (DGVM) models such as TRENDY v.9 provide gross fluxes and offer additional insight. 

We here discuss monthly net CO2 fluxes from 2009-2018 from three different semi-arid regions in the southern hemisphere, i.e. Australia, South American Temperate region and South Africa. For all three regions we find that the DGVMs are not consistent suggesting different carbon dynamics. Despite similar landuse types, the DGVMs best matching the inversion results, differ across the regions.

 However, we find that in all three semi-arid regions the seasonal increase in net ecosystem exchange (NEE) occurs shortly after the onset of rainfall. NEE is driven by an early increase in heterotrophic respiration, whereas the autotrophic respiration remains in phase with the GPP and is delayed with respect to heterotrophic respiration. This process strongly shapes the seasonal cycle in the semi-arid regions, and in Australia, dominates the interannual variation. Our findings suggest that soil rewetting processes in semi-arid areas play an important role in constraining the global carbon budget and should be represented more accurately in global carbon cycle models to improve the estimation of the global carbon budget.  

 

216 Is urban carbon sequestration a myth or a fact?

Poster

Erik Velasco*

Molina Center for Energy and the Environment, Boston, USA

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Limited knowledge on urban biogeochemistry and a lack of holistic assessments that include every component of urban forestry jeopardize the effectiveness of policies that promote vegetation as a means of mitigating climate change. Integral assessments that include plants and soil, as well as carbon emissions associated with irrigation and gardening activities for maintaining aesthetic grounds, are required to determine the capability of urban greenery to offset anthropogenic emissions of carbon dioxide (CO2). Plants remove CO2 by photosynthesis; a large fraction is consumed in biomass production, especially by young trees; mature trees do so to a lesser extent. The rest is transferred belowground. Once there, much of it returns to the atmosphere by soil respiration, leaving only a small fraction in the soil that may later be lost through leaching. Only a tiny fraction makes it through the mineralization process, which takes hundreds to thousands of years. Also, do not forget about the gardening waste fate. In this context, this talk will explain how trees, turfgrass, and soil regulate carbon exchange in sidewalks, parks, gardens, and lawns, based on a series of unique field experiments conducted in Singapore and Mexico City. These included eddy covariance flux measurements, tree surveys, the development and application of allometric models, turfgrass sampling, and continuous soil respiration measurements. It is important to identify and implement gardening practices that promote carbon storage while reducing the impact of maintenance activities. Bear in mind that cities are disturbed ecosystems, thus urban vegetation cannot respond as a natural ecosystem does.

 

217 Comparing the Environmental Response of Carbon Dioxide and Methane Flux Dynamics in a Boreal Bog and Fen

Poster

Eyrún Gyða Gunnlaugsdóttir1*, Eeva-Stina Tuittila2, Angelika Kübert1, Aino Korrensalo3,4, Elisa Männistö2, Xuefei Li1, Timo Vesala1, Ivan Mammarella1

1University of Helsinki, INAR/Physics, Helsinki, Finland. 2Peatland and soil ecology research group, School of Forest Sciences, University of Eastern Finland, Joensuu, Finland. 3Department of Environmental Sciences and Biology, University of Eastern Finland, Kuopio, Finland. 4Luke, Joensuu, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Peatlands store a large part of the global soil carbon. These carbon stocks are at risk of being released into the atmosphere, due to warming temperatures and lowered water table levels.
   Peatlands can be classified as bogs and fens, depending on their water supply. Fens tend to be more nutrient-rich and less acidic. Because of these different environmental factors, different types of vegetation thrive in these ecosystems, with Sphagnum mosses being more abundant in bogs and aerenchymatous vascular plants in fens.
   This research focuses on comparing carbon dioxide (CO2) and methane (CH4) flux response under different environmental circumstances at Siikaneva bog and fen, located in the boreal zone in Southern Finland. They share the same climate due to their close vicinity, being 1.3 km apart. Eddy Covariance data of CO2 and CH4 fluxes during the growing season from the years 2011-2016 was used in this research. Our preliminary results indicate that the bog shows milder temporal variability and is less responsive to changes in temperature. The emission peak of CH4 happens later in the fen and lasts longer. Further, the CHflux response of soil temperature is highest for the fen at 35 cm depth but at 20 cm depth for the bog. 
   Our further analysis aims to isolate weather anomalies and identify the difference in flux response to extreme weather events between the bog and the fen. We will answer further questions about the future responses of COand CH4 fluxes in a changing climate for bogs and fens.

 

218 Quality control and annual uncertainty of direct flux measurements to address greenhouse gas emissions and land subsidence in Dutch peatlands

Poster

Alexander Buzacott1*, Quint van Giersbergen2, Laurent Bataille3, Jan Biermann4, Wietse Franssen3, Christian Fritz2, Ype van der Velde1, Bart Kruijt3

1Vrije Universiteit Amsterdam, Amsterdam, Netherlands. 2Radboud University, Nijmegen, Netherlands. 3Wageningen University, Wageningen, Netherlands. 4Wageningen, Wageningen, Netherlands

Session 14. Leveraging Direct Flux Measurements Beyond Academia for Real-World Applications

Flux measurements by the eddy covariance method have been crucial to advance our understanding of the exchange of energy and greenhouse gases (GHG). The declining costs of equipment and increased power efficiency of fast trace gas analysers has enabled the use of the eddy covariance method to address nation specific GHG challenges and to develop emission mitigation strategies. Peatlands are impressive stores of soil carbon and account for 30% of storage globally, despite only covering 3% of the land surface. The Dutch peatlands have been drained for centuries to create more arable land and were exploited as a fuel source. Drainage of peatlands causes in aerobic microbial peat oxidation, resulting in high CO2 emissions and land subsidence. To meet emission goals, the Dutch government made a climate agreement to reduce peatland emissions by 1 Mton CO2 by 2030. The NOBV project was set up to understand peatland GHG emissions and to determine optimal strategies to reduce GHG emissions. In this presentation, we introduce our EC network monitoring fluxes on Dutch peatlands and explore some of the challenges that nation scale flux networks have with data quality and control, with a focus on the effect on annual flux totals of CO2 and methane (CH4). We examine the balance between filtering of the data for quality and increasing statistical power for more certainty in the annual totals. Annual totals are important in our case to estimate peat oxidation, and real management and policy decisions depend upon the outcome of these totals.

 

219 Spatially comprehensive modelling of methane emissions in northern latitude peatlands

Poster

Koffi Dodji Noumonvi1*, Joshua L. Ratcliffe1,2, Mats G. Öquist1, Natascha Kljun3, Johan E. S. Fransson4, Mats B. Nilsson1, Matthias Peichl1

1Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden. 2Unit for Field-Based Forest Research, Swedish University of Agricultural Sciences, 922 91 Vindeln, Sweden. 3Centre for Environmental and Climate Science, Lund University, 223 62 Lund, Sweden. 4Department of Forestry and Wood Technology, Linnaeus University, 351 95 Växjö, Sweden

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Wetlands in general and specifically northern peatlands are an important natural source of atmospheric methane. This is particularly true for high latitudes since they are undergoing the fastest climatic changes, potentially affecting methane emissions from these ecosystems. Methane flux measurements are conducted across various northern latitude peatland sites using the eddy covariance (EC) technique, providing reliable estimates of ecosystem-scale methane fluxes for these ecosystems. However, these measurements generally originate from single sites, raising uncertainties on their spatial representativeness, considering that northern peatlands can occur as large heterogeneous units termed as peatland complexes. This further introduces uncertainties in global models benchmarked with these data, and the need for replicated ecosystem level methane measurements. Leveraging a network of four adjacent sites within the Kulbäcksliden peatland complex in Northern Sweden, half-hourly flux estimates based on EC measurements are related to environmental properties within the footprints from which they originate. These include high-resolution vegetation indices from Sentinel-2 satellite and unmanned aerial vehicle (UAV) images, peatland surface microtopography, spatially modelled water table depth, soil temperature, and site peat characteristics like C:N ratio or bulk density. Machine learning algorithms such as XGBoost or Random Forest are employed to disentangle the spatial complexities of the relationship between measured methane fluxes and their drivers. Results from this work provide a better insight on the contribution of different components of a peatland complex to methane fluxes and pave the way for more spatially and temporally comprehensive modelling of methane emissions from peatlands, particularly large peatlands or peatland complexes.

 

220 Influence of Atmospheric Transport in Inversions using Greenhouse Gas Column measurements: A Study with MUCCnet in Munich

Oral

Haoyue Tang1*, Jia Chen1, Andreas Luther1, Junwei Li1, Moritz Makowski1, Christopher Holst2, Changxing Lan2, Christoph Knote3

1Environmental Sensing and Modeling (ESM), Technical University of Munich, München, Germany. 2Institute of Meteorology and Climate Research—Atmospheric Environmental Research, Karlsruhe Institute of Technology, Garmisch-Partenkirchen, Germany. 3Model-based Environmental Exposure Science, Faculty of Medicine, University of Augsburg, Augsburg, Germany

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Quantification of greenhouse gas (GHG) emissions is crucial for shaping climate action plans. The assessment of urban GHG emissions through the Bayesian inversion of column measurement data offers an effective method. Within this Bayesian inversion process, the quality of the emission estimates is dominated by the quality of the transport model. Understanding the impacts of various transport models can enhance the accuracy of emission inversion results.

This research utilizes EM27/SUN column measurements for Bayesian inversion in Munich, spotlighting the influence of varying meteorological fields. We employ the European Centre for Medium-Range Weather Forecasts Reanalysis 5 (ERA5) and the Weather Research and Forecasting (WRF) model with distinct setups to drive the Stochastic Time-Inverted Lagrangian Transport (STILT) model, generating backward trajectories of particles and a background influence matrix. Various wind observations, including Doppler Lidar wind profiles, are utilized to assess and amend transport errors, quantifying the diverse transport inaccuracies inherent in Bayesian inversion. Moreover, the study incorporates WRF-Chem for forward modeling of greenhouse gases, using optimized emission inventory from the inversion to generate a greenhouse gas flux field for Munich. This approach allows for the evaluation of inversion effectiveness through comparison with actual flux measurements. This comprehensive assessment sheds light on the substantial impact of transport models on greenhouse gas Bayesian inversion, providing valuable insights that could inform future environmental policies and research in urban GHG monitoring.

 

221 Scientist’s toolkit: How to get media visibility for your research?

Oral

Karlina Ozolina*, Maria Luhtaniemi

ICOS ERIC, Helsinki, Finland

Session 15. Science communication and outreach to increase the impact of climate research

Climate science is vital to communicate to society, but far too many impactful research papers never break through to national or international media. While lack of resources is a known challenge in science communications, there are ways in which all of us can become better science communicators. 

The purpose of this presentation is to share practical tips with scientists on how to use their own social media skills and presence to gain visibility for their research, for example, by using their personality and storytelling to showcase the heart behind their research project. Furthermore, this presentation highlights how to best make use of the resources available in scientific institutes or wider research networks. The practical session moves from sharing inspiring examples of science communications on social media to tips on how to shape an engaging narrative for your press release. To illustrate this, the session presents some successful communications, facilitated by the ICOS Head Office communications team, that brought visibility to studies from the ICOS community.  

The purpose of this presentation is to provide ICOS scientists with more confidence, tools and inspiration for increasing the visibility of their research, either through their own networks or through utilising the skills and expertise of the communications teams of their institutions.  

 

222 Implementing shrub plant functional types to improve the representation of high latitude vegetation in ORCHIDEE

Poster

Anna Kirchner1*, Efrén López-Blanco2, Philippe Peylin3, Sebastiaan Luyssaert4, Vladislav Bastrikov5, Anne Sofie Lansø1

1Department of Environmental Science, Aarhus University, Roskilde, Denmark. 2Department of Ecoscience, Aarhus University, Roskilde, Denmark. 3Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France. 4Department of Ecological Science, Vrije Universiteit Amsterdam, Amsterdam, Netherlands. 5Science Partners, Paris, France

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Under amplified global warming, high-latitude terrestrial regions are already experiencing observable changes in vegetation dynamics, including an Arctic greening linked to an increase in productivity and an expansion of shrubs across tundra ecosystems. Since these dynamics alter the local-to-regional carbon cycle and hold potential for global climate change feedbacks, it is important to capture such changes in plant traits and species distribution in global land surface models (LSMs) to improve their capability to represent current and future climate changes. However, the LSM ORCHIDEE, like several other LSMs, is lacking high-latitude plant functional types (PFTs), including shrubs, limiting its ability to capture these changes and their impacts on carbon and surface energy balances. To improve the representation of high-latitude vegetation and the model’s ability to capture and project high-latitude greenhouse gas fluxes, we introduce several types of Arctic shrubs into the latest version of ORCHIDEE. The shrub PFTs differ from the model’s boreal tree PFTs in their carbon allocation and resistance to harsher climatic conditions and have higher biomass stocks and carbon fluxes than boreal grasses, which dominate high-latitude regions in the current model version. We use observations of carbon fluxes, biomass and other plant traits to calibrate the model, by identifying shrub-dominated sites across the circumpolar region in the ICOS, FluxNet and other databases. This work lays the foundation to model important changes in high-latitude vegetation dynamics, such as shrubification, their interactions with snow and permafrost dynamics and their climate feedback potential in ORCHIDEE.

 

223 Capabilities of CH4 source apportionment using atmospheric 14CH4 measurements: Switzerland as a case study

Oral

Thomas Laemmel1,2*, Dylan Geissbühler1,2, Stephan Henne3, Dominik Brunner3, Negar Haghipour4, Markus Leuenberger5,2, Sönke Szidat1,2

1Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland. 2OCCR - University of Bern, Bern, Switzerland. 3Laboratory for Air Pollution/Environmental Technology, Empa, Dübendorf, Switzerland. 4Laboratory for Ion Beam Physics, Department of Physics, ETH Zurich, Zürich, Switzerland. 5Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland

Session 1. Isotopes and other tracers for studies of methane sources and sinks

CH4 is the second most important anthropogenic greenhouse gas after CO2. While biogenic emissions of CH4 (from agriculture, waste management or wetlands) contain present-day atmospheric radiocarbon (14C) levels, CH4 derived from fossil sources is 14C-free so that 14CH4 measurements can be used for source apportionment. A dedicated setup to analyze 14CH4 was developed at the Laboratory for the Analysis of Radiocarbon with AMS (LARA), University of Bern. Typical samples are 60L of atmospheric air collected in bags, which, after extraction result in about 60µg carbon in CH4-derived CO2 form, enough for a 14C gas measurement on an accelerator mass spectrometer equipped with a gas interface system.

 Since 2019, biweekly air samples have been collected at six sites in Switzerland: the high-altitude research station Jungfraujoch considered as a European continental background station, four tall towers distributed across the Swiss plateau, and an urban site in Bern. In parallel, an atmospheric 14CH4 transport model was developed to simulate 14CH4 values for each sample. It is based on the Lagrangian particle dispersion model FLEXPART, CH4 emission inventories, a priori 14CH4 signatures for each emission type and the regional weather model COSMO. 14CH4 emissions from European nuclear power plants (NPPs) are also taken into consideration.

 This contribution will present the in situ 14CH4 measurements as well as corresponding simulations and emphasize that the emissions and transport of 14CH4 emitted from European NPPs are greatly influencing the overall signal measured over the Swiss plateau, making CH4 source apportionment very challenging.
 

224 In-situ NOx observations using the German ICOS tall tower setup

Poster

Tobias Kneuer1*, Robert Holla1, Jennifer Mueller-Williams1, Matthias Lindauer1, Jia Chen2, Dagmar Kubistin1

1Deutscher Wetterdienst, Meteorological Observatory Hohenpeissenberg, Hohenpeissenberg, Germany. 2Environmental Sensing and Modeling, Technical University of Munich, Munich, Germany

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

In-situ greenhouse gas (GHG) measurements on ICOS tall towers continuously provide high-quality and high temporal resolution data on atmospheric dry mole fraction in the lowest few hundred meters of the atmosphere. Supplementary measurements of species that are co-emitted by anthropogenic activities, such as nitric oxide (NO) and nitrogen dioxide (NO2), could aid in attributing these GHG observations to specific emission sectors such as transportation, industry and energy production. These short-lived trace gases are observed within the European Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS).

Expanding ICOS GHG observations with ACTRIS NOx (NO + NO2) measurements will provide valuable insights into emissions from different sectors. At ICOS tall tower sites, long in-take lines extending up to a few hundred meters, are used to draw ambient air into a temperature-controlled container, housing the GHG analyzers. Utilizing the existing infrastructure for NOx observations demands a thorough characterization of the sampling setup, particularly considering the reactivity of NO and NO2 and surface reactions in the inlet line. 

Here, we present a potential configuration for conducting in-situ NOx observations at German ICOS tall tower sites and its associated uncertainties using the Cavity Attenuated Phase Shift (CAPS) technique. Our theoretical and experimental analysis considers potential inlet line effects, including chemical reactions occurring during long residence times in the sample line. Furthermore, we will present ambient air NOx measurements obtained from a setup used at German ICOS tall towers.

 

225 Luke GHG flux network on northern managed ecosystems

Poster

Janne Rinne1*, Samuli Launiainen1, Maarit Liimatainen2, Raisa Mäkipää1, Aleksi Lehtonen1, Perttu Virkajärvi3, Narasinha Shurpali3, Tero Toivonen3, Anssi Liikanen1, Juho Kinnunen4, Petri Salovaara1, Anne Ojala1, Sanna Sorvari Sundet1, Olli Peltola1

1Natural Resources Institute Finland, Helsinki, Finland. 2Natural Resources Institute Finland, Oulu, Finland. 3Natural Resources Institute Finland, Maaninka, Finland. 4Natural Resources Institute Finland, Ruukki, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Nordic countries are commonly seen as countries of wild boreal forests, wetlands and lakes. However, majority of forests in Finland and Sweden are managed for forestry and both countries have significant agricultural sectors that provide self-sufficiency in basic agricultural products. Agricultural land covers 7-8 % of land area, and with the potential decline in agricultural conditions in Southern Europe, there may be a pressure to increase agricultural production in the future. Of forest land, more than 90 % is under economically driven management, as forestry is a major economic sector in both countries.

High-level data is prerequisite for quantification and understanding the GHG balances of the managed ecosystems. To contribute to these needs, Luke operates five eddy covariance flux sites in agricultural systems and one at a recently clear-cut and seeded drained peatland forest. The agricultural sites consist of both mineral and organic soils. Maaninka-Anttila (FI-Ant) forage grass site on mineral soil is undergoing the ICOS labeling process to become a Class 2 ecosystem station. The forest site provides data on GHG exchange of a clear-cut forest on drained nutrient rich peatland to compare, adjacent to a flux site measuring GHG-balance of a continuous cover forestry. 

All the sites measure the fluxes of the three major GHGs (CO2, CH4, N2O) in identical set-ups. The data is processed centrally with ICOS compliant data processing pipeline. We will present the Luke flux measurement network, data pipeline, and provide examples of the means and variability of GHG fluxes across our managed ecosystems.

 

227 Story on the attempt to industrialize low-cost eddy-covariance measurements

Poster

Timo Vesala1*, Ivan Mammarella1, Üllar Rannik1, Mika Korkiakoski2, Hilkka Heiskari-Tuohiniemi3, Pirkko Väkimies3

1University of Helsinki, Helsinki, Finland. 2Finnish Meteorological Institute, Helsinki, Finland. 3Vaisala Oyj, Vantaa, Finland

Session 14. Leveraging Direct Flux Measurements Beyond Academia for Real-World Applications

Greenhouse gas flux measurements start to play increasingly important role outside academia in assessing carbon sinks of different ecosystems and land-use types. In order to monetize and deploy dense carbon assesment solutions in future carbon markets, more low-powered and low-cost flux systems should be deployed. Low-cost sensors fulfilling the requirements for scientific applications are increasingly needed.

We present a case study where Vaisala company in collaboration with the University of Helsinki combined their industrial and academic expertise to create an operational eddy covariance (EC) setup with a low-cost gas analyser. The setup was intended to be affordable, low-powered, easy-to-use, and require minimal maintenance. Created prototype EC station represented a compromise in terms of accuracy, reliability, and affordability. We secured joint funding for a post-doctoral researcher from the Finnish Research Impact Foundation. The project lasted two years and involved significant in-kind contributions from both Vaisala and university.

A working prototype was co-developed, and field tested against a scientific reference EC set-up. The project had special emphasis on response time, reduced sampling frequency, simultaneous measurement of water vapor, and temperature-related autocalibration. The results achieved at the end of the project were very promising, leading to plans for continued work both at Vaisala and university.

However, a deeper market analysis revealed that the market in the year 2022 was not sufficiently large to justify Vaisala&apos;s investments. Therefore, Vaisala halted further development of the sensor.

 

228 Biogenic CO2 fluxes in different urban vegetation types in Helsinki, Finland

Oral

Liisa Kulmala1*, Laura Thölix1, Leif Backman1, Minttu Havu2,3, Esko Karvinen1, Jesse Soininen2, Leena Järvi2

1Finnish Meteorological Institute, Helsinki, Finland. 2Universiy of Helsinki, Helsinki, Finland. 3CNRM/Meteo-France, Toulouse, France

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Many cities aim for carbon neutrality, prompting interest in the potential of urban vegetation as carbon sinks. In addition, accurate estimation of emission reductions requires understanding the size and dynamics of natural carbon fluxes. However, the heterogeneous nature of urban vegetation and environmental conditions poses challenges for comprehensive measurement efforts and thus sets expectations for carbon cycle modelling. This study evaluates the performance of three models - JSBACH, LPJ-GUESS, and SUEWS - in estimating biogenic CO2 fluxes and carbon sequestration rates across various urban vegetation types in Helsinki, Finland, including irrigated and non-irrigated lawns, park trees, and urban forests. Environmental parameters such as soil moisture, temperature, sap flow, leaf area index, instantaneous photosynthesis, soil respiration, and net ecosystem exchange were analyzed. Additionally, JSBACH was tested for dry and mesic urban meadows.  Results indicate that the models effectively simulate seasonal variations and weather event effects on carbon fluxes and related factors. However, validating absolute fluxes proved challenging due to observational limitations, especially for mature trees and net ecosystem exchange measurements, which also include some anthropogenic emissions in urban areas. Despite these challenges, irrigation emerged as a key factor, usually enhancing carbon sequestration, with tree-covered areas exhibiting higher rates compared to grass types on an annual scale.

 

229 Diurnal profiles of volatile organic compounds emitted from an agricultural area

Poster

Stanislav Juran1*, Thomas Karl2, Otmar Urban1

1Global Change Research Institute CAS, Brno, Czech Republic. 2University of Innsbruck, Department of Atmospheric and Cryospheric Sciences, Innsbruck, Austria

Session 2. Exchange of reactive gases and aerosols between the land surface and the atmosphere in natural and managed ecosystems

Biogenic (BVOCs) and anthropogenic (AVOCs) volatile organic compounds play pivotal roles in atmospheric chemistry due to their fast reactivity and high potential for tropospheric ozone formation. Diurnal courses of BVOCs and AVOCs over an agricultural site were measured using the PTR-TOF technique from spring to autumn of 2023. The site, Křešín u Pacova (CZ; 49.572N, 15.08E), forms a part of the ICOS station network (atmosphere station, class 1) and is covered by arable land with patches of forests. Here we present diurnal courses of monoterpenes, isoprene, and 2-methyl-3-buten-2-ol (232MBO). The results show that the hot summer period in July is associated with high nighttime concentrations of monoterpenes due to boundary layer shrinking. In contrast, concentrations of other BVOCs (e.g., 232MBO, isoprene) peak during the central hours of the day, suggesting that their emissions are likely sunlight-driven. 

To identify pollution related to the operation of the research infrastructure, the ratio of toluene and benzene concentrations was also investigated. Typically, the ratio is high (>1.5) at polluted sites and close to one at clean locations. Here, overnight maxima amounted to 1.6, indicating that fresh AVOC emissions are close to the sampling point. Oil drops and leakage from diesel engine of the atmospheric tower elevator was identified as a likely source of such emissions.

Acknowledgements

We acknowledge support from AdAgriF - Advanced methods of greenhouse gases emission reduction and sequestration in agriculture and forest landscape for climate change mitigation (CZ.02.01.01/00/22_008/0004635).
 

230 Quantification of Hotspot Emissions Using Ground-Based Spectral Imaging of Methane and Carbon Dioxide

Poster

Lennart Resch1*, Marvin Knapp1, Häffner Lukas1,2, Lousia-Marie Rüther1, Alberto Alvaro-Diaz3, Cristina Prados-Roman3, André Butz1,4,5

1Institute of Environmental Physics, Heidelberg, Germany. 2German Environment Agency, Dessau-Rosslau, Germany. 3Dept. Earth Observation and Space Science, National Institute for Aerospace Technology (INTA), Madrid, Spain. 4Heidelberg Center for the Environment (HCE), Heidelberg, Germany. 5Interdisciplinary Center for Scientific Computing (IWR), Heidelberg, Germany

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Spectroscopic imaging of greenhouse gases (GHG) from satellites and planes is an emerging tool for quantifying GHG emissions occurring in urban contexts. Particularly hotspot sources of carbon dioxide (CO2) and methane (CH4), such as coal-fired power plants, landfills, and oil & gas facilities, are accessible by remote sensing methods. Precise quantification of these hotspots is essential to discriminate their contribution to area-wide budgets from other source sectors.

We operate a ground-based spectral camera in a stationary viewing geometry, enabling repeated observations of a source over prolonged periods under km-scale distances. An adapted matched filter retrieval quantifies column enhancements of CO2 and CH4 from the recorded solar absorption spectra in the 2.0 µm and 2.3 µm regions, respectively. Our precursor studies demonstrate our ability to quantify enhancements in emission plumes from strong point sources, like CH4 from underground coal mining (Knapp et al., 2023) or CO2 from coal-fired power plants (Knapp et al., 2024). High-frequency plume imaging enables emission estimation with sub-hourly (CH4) to hourly (CO2) temporal resolution for emission hotspots, complementing existing monitoring capacities.

We will operate the camera at the Pinto landfill in Madrid, Spain, during the Madrid Methane Remote Sensing (M-MRS 2024) field campaign in summer 2024. Landfills are intermittent and diffuse sources of CH4 with significant uncertainties and mitigation potential. This proof-of-concept campaign aims to evaluate our methodology for landfills, and we intend to present initial findings regarding methane plume observations and emission estimates.

Knapp et al., 2023 (doi: 10.1088/1748- 9326/acc346)

Knapp et al., 2024, (doi: 10.5194/egusphere-2023-1857)

 

231 Provisional title :Modelling N2O emissions from cropland in clay soils

Poster

Puginier Thomas*, Ceschia Eric, Jarosz-Pelle Nathalie, Tallec Tiphaine

CESBIO, Toulouse, France

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Provisional abstract :

Cultivated soils are a major source of global anthropogenic N2O emissions due to the use of N fertilizers. The two main processes responsible for these fluxes are (1) nitrification, the oxidation of ammonium into nitrite and nitrate, and (2) denitrification, anaerobic microbial respiration. These fluxes are still poorly understood because they are difficult to measure and model due to their sporadic nature. They depend on numerous factors that are strongly influenced by the nature of the soil and so far few studies have focused on clay soils. 

Therefore, the aim of this study is to test two process-based modules, NOE and NOE2, in their ability to simulate N2O fluxes on highly clayey cropland soils.  For this we have used   fluxes measured during 3 years with automatic chambers at two ICOS sites (FR-AUR and FR-LAM) located in South-West France.

Preliminary results show that the N2O fluxes dynamics are simulated correctly with default parameters for both models (RMSE of 7.68 and 5.15   , for NOE and NOE2 respectively). Yet we consider that a specific parametrisation for clayey soils of those models could improve their performances, in particular for the denitrification potential parameter. Therefore, the results of a site-specific bayesian calibration of these parameters will be presented and evaluated.  In the future, NOE or NOE2 will be coupled to the SAFYE-CO2  model, which enables the spatialized simulation of biomass, water and carbon cycle at intra-plot scale, in order to simulate spatialized N2O fluxes.

 

232 The CDRatlas: A platform to visualize the potential of CDR

Oral

Steffen Swoboda*, Viola Schaber, Andreas Oschlies

GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany

Session 13. In situ data for climate and other environmental services and policy support

The repercussions of climate change and measures for its mitigation are among the most pressing challenges of modern society. Emission reduction scenarios indicate that negative emissions, i.e. “carbon dioxide removal” (CDR), are a necessity to reach the goals of the Paris Agreement. However, the development and implementation of CDR is constrained by limited accessibility of relevant information. To overcome this, we build an open access web tool, termed the CDRatlas, that provides relevant information on the implementation and potential of commonly considered marine and terrestrial CDR approaches. The information is presented on an intuitive and interactive web-platform by a combination of (1) process chain assessments, (2) geospatial data visualization and (3) additional text-based information. The process chains identify the relevant steps for the implementation of a respective CDR approach. Based on these steps, data is gathered and presented in form of map layers or as text-based information. This will allow decision makers to identify the ecological and technological readiness and capacities along the relevant steps for the implementation of the depicted CDR measures. This enables the identification of measures for the direct implementation and strategic development of CDR. In addition, all information and data are openly accessible and either harvested from existing platforms or stored in data repositories. Further, displayed information is presented in an easily understandable manner, allowing non-experts to get an overview of the subject. As a result, the CDRatlas will serve as a knowledge interface from the scientific community to members and actors within society.

 

233 Global CO2 inversions with chemical production from CO

Oral

Remco de Kok1*, Ingrid Luijkx1, Bo Zheng2, Anne-Wil van den Berg1, Wouter Peters1

1Wageningen University and Research, Wageningen, Netherlands. 2Tsinghua Shenzhen International Graduate School, Shenzhen, China

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Every year, a top-down estimate of the global carbon budget using atmospheric inversions is performed as part of the Global Carbon Project (Friedlngstein et al., 2023). Furthermore, other initiatives, such as OCO-2MIP (e.g Crowell et al., 2019), provide a similar ensemble of top-down estimates of global CO2 fluxes. A common assumption in these inversions is that all CO2 that is measured in the atmosphere is also emitted to the atmosphere in the form of CO2. In reality, part of the atmospheric carbon is emitted in a more reduced form (e.g. CO or CH4) and is later oxidised in the atmosphere to form CO2. This effect is expected to influence the CO2 flux estimates from inversions (e.g. Enting & Mansbridge, 1989; Sunthatalingam et al., 2005; Wang et al, 2020). Here, we present the results from atmospheric inversions that include the atmospheric chemical production of CO2 from CO, which is constrained by an independent atmospheric inversion based on satellite CO column retrievals. Our long timeseries results (2000-2021) allow for the assessment of robust seasonal cycles and trends in the effect of the atmospheric CO2 production on the global and regional CO2 inversions Furthermore, we investigated the effect of two different data sampling strategies.

 

References:

Crowell et al., 2019, doi: 10.5194/acp-19-9797-2019

Enting & Mansbridge 1989, doi: 10.3402/tellusb.v41i2.15056

Friedlingstein et al., 2023, doi: 10.5194/essd-15-5301-2023

Suntharalingam et al., 2005, doi: 10.1029/2005GB002466

Wang et al., 2020, doi: 10.1088/1748-9326/ab9795

 

234 Atmospheric methane behavior in an Atlantic coastal environment in the Southwestern Europe.

Poster

Rubén Padilla1*, José Antonio Adame1, Pablo Hidalgo2, Juan Pedro Bolívar2, Margarita Yela3

1Atmospheric Sounding Station. El Arenosillo. National Institute for Aerospace Technology (INTA), Mazagón - Huelva, Spain. 2Department of Integrated Sciences. Center for Natural Resources, Earth and Environment (RENSMA). University of Huelva, Huelva, Spain. 3Department of Earth Observation and Space Science. National Institute for Aerospace Technology (INTA), Torrejón de Ardoz - Madrid, Spain

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Atmospheric methane (CH4) was registered in an Atlantic coastal area of Southwestern Europe, El Arenosillo observatory. The study covered a four-year period (September 2019 – December 2023).  Based on daily averages a short-term trend of 12.1 ± 1.1 nmol mol-1 year-1 was found. Regarding the monthly evolution, the maximum was measured in winter (~1994 nmol mol-1) while the minimum was found in summer (~1961 nmol mol-1). A seasonal diurnal cycle was also observed, with peaks at 7:00 – 8:00 UTC and minima registered at 18:00 – 19:00 UTC. To investigate its dynamics, we studied CH4 in an atmosphere governed by synoptic scale. Atmospheric dynamic was analysed with the wind fields from ERA5 data reanalysis and the air masses pathways with the back-trajectories computed with the HYSPLIT model. While the CH4 horizontal distribution was explored with the TROPOMI observations. Baseline CH4 levels (~1960 nmol mol-1) were collected under the influence of Atlantic air, while an increase from 20 to 80 nmol mol-1 was found under the influence of continental airflows, coming from the inland Guadalquivir valley. 

During the development of mesoscale processes (such as sea-land breezes), frequent in this coastal area, no increase in CH4 was observed. However, the horizontal distribution from TROPOMI showed an accumulation over the marine area of the Gulf of Cádiz. Among other objectives, the ongoing CH4 observations will be used in future studies, to identify potential changes in its trend, as well as to understand the potential contribution of the CH4 transported from the Western Mediterranean Basin and other areas.

 

235 Combined CO2 and O2 measurements for process-specific partitioning and carbon budgeting

Poster

Markus Leuenberger1,2*, Peter Nyfeler1,2, Rüdiger Schanda1,2, Vasileios Mandrakis1,2, Stephan Räss1,2, Michael Schibig3,1,2

1Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland. 2Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland. 3Federal Office for the Environment, Bern, Switzerland

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

We measured combined CO2 and O2 measurements at different locations in Switzerland. On the roof of our laboratory at the University of Bern, we installed an aspirated intake and are able to distinguish urban combustion from biogenic signals based on their differences in oxidation ratios (OR). At the tall tower Beromünster, we have installed five inlet systems at different heights. This allows us to observe differences of biogenic OR values during night (respiration) and day (combination of photosynthesis and respiration) as well as follow the dilution process of biosphere signals originating from the soil and surface due to mixing with atmospheric air at different intake heights. Additionally, at Jungfraujoch combined CO2 and O2 measurements allow us to partition the CO2 emissions due to its main sink reservoirs, i.e. the ocean, land and the atmosphere. The presentation will highlight the potential of combined CO2 and O2 measurements for the quantification of OR values and CO2 emission partitioning.

 

236 Impact of climate extremes on air-sea CO2 exchanges in the North Western Mediterranean Sea: A study based on the MOOSE network

Oral

Anthony Bosse1, Gaëlle Capitaine1,2, Laurent Coppola3, Dominique Lefevre1, Pierre Testor4, Caroline Ulses5, Thibaut Wagener1*, Cathy Wimart-Rousseau6,7

1Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France. 2Laboratoire National de Métrologie et d’Essais (LNE), Paris, France. 3Sorbonne Université, CNRS, OSU Station Marines, STAMAR, Paris, France. 4Sorbonne Université, CNRS, IRD, MNHN, Laboratoire d’Océanographie et de Climatologie (LOCEAN), Paris, France. 5Université de Toulouse, LEGOS (CNES, CNRS, IRD, UT3), Toulouse, France. 6GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany. 7National Oceanography Centre (NOC), Southampton, United Kingdom

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

The Mediterranean Sea is considered to be a “hotspot” for climate change with effects occurring on faster time scales than the global ocean. It is particularly affected by extreme climatic events with very high temperatures at the sea surface during summer and reduced ventilation of intermediate and deep water masses by winter convection as observed by moored time series. In the framework of the MOOSE sustained observing network (CNRS-INSU), observations of inorganic carbon chemistry based on discrete sampling from the surface to the bottom have been collected since 2010 in the North-Western Mediterranean Sea during monthly oceanographic cruises at fixed stations and every year during a basin scale cruise (MOOSE-GE, https://doi.org/10.18142/235).

In this study, the main results on the seasonal variability of CO2 exchanges between the atmosphere and the surface, intermediate and deep ocean and on long-term changes (decadal trends) in inorganic carbon chemistry will be presented. The main objectives of this study are to assess (1) the effect of extremely hot summer temperatures on the air-sea CO2 exchanges at a seasonal scale and (2) the effect of reduced winter convection on the inorganic carbon content of the upper water column at the scale of decadal trends from individual stations to the entire N.W. Med. Sea. In conclusion, we propose improvements of the MOOSE network’s inorganic carbon chemistry observation strategy to better monitor and understand the effect of climate extremes on CO2 fluxes. 

 

237 A MRV system implemented as fully automated reproducible self-documenting workflow

Poster

Arndt Meier1,2, Guillaume Monteil2,3, Ute Karstens1,2, Marko Scholze2, Alex Vermeulen1,2*

1ICOS ERIC - Carbon Portal, Lund, Sweden. 2Lund University, Lund, Sweden. 3Now at: Barcelona Supercomputing Centre, Barcelona, Spain

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The ICOS research infrastructure collects, maintains and supports a large range of high quality and long-term greenhouse gas observations in its FAIR data repository Carbon Portal (CP), together with inventory, modelled surface fluxes and ancillary data. All of these receive unique persistent identifiers as key pre-requisite for achieving reproducible scientific workflows. 

Here we present a self-documenting, fully reproducible workflow for our inverse carbon model system LUMIA that builds on the CP infrastructure and methods. The Lund University Modular Inversion Algorithm (LUMIA) has been developed at the Lund University hosting department of CP for inverse modelling of carbon dioxide and (isotope resolved) methane. The model uses as input observational and prior flux data like those mentioned before. The overarching goal of this so called top-down inverse method is to provide optimised emission fields based on observations. Next to common and scientific interest, the method also can inform policy makers on the progress in reaching the goals of the 2015 Paris agreement, through independent estimates of emissions and natural fluxes. For this purpose an open, flexible, transparent, modular and reproducible system like presented here is needed. 

The design goals include using the system as demonstrator of the general principle of the use of inverse modelling tools based on simplified and reduced datasets, to perform network design for observational systems based on real and synthetic data sets, up to full blown regional inversions in a MRV (Measurement, Reporting and Verification) system based on all available data, including an analysis of uncertainties. 

 

238 Evaluation of Ground-Based PAR Quantum Sensors for fAPAR Estimation: Quality Control and Uncertainty Assessment

Poster

Rémi Grousset1*, Gabriele Bai2, Christophe Lerebourg2, Somnath Paramanik3, Finn James3, Jadu Dash3, Ernesto Lopez-Baeza4, Ana Perez-Hoyos4, Alexander Knohl5, Anne Klosterhalfen5, Frank Tiedemann5, Nadine Gobron6, Marco Clerici6

1ACRI-ST, Toulouse, France. 2ACRI-ST, Sophia Antipolis, France. 3University of Southampton, Southampton, United Kingdom. 4Albavalor, Valencia, Spain. 5University of Goettingen, Goettingen, Germany. 6JRC, Ispra, Italy

Session 13. In situ data for climate and other environmental services and policy support

Long term ground-based measurements are of prime importance for the validation of remote sensing methods for vegetation variables retrieval. While Digital Hemispherical Photography (DHP) measurements have traditionally been employed, Photosynthetically Active Radiation (PAR) quantum sensors have sparsely been evaluated as ground-based sensors for estimating fraction of Absorbed Photosynthetically Active Radiation (fAPAR). To leverage PAR data effectively, stringent quality control (QC) procedures and end-to-end uncertainty propagation are imperative. QC is crucial due to potential disturbances, including device variations, vegetation shadows, and cloud cover (especially under scattered clouds environment). We investigate four QC methods: comparison between above-canopy and below-canopy sensors, intensity prediction based on solar zenith angle, consistency of above-canopy sensor readings, and hull methods. Performance evaluation of these methods is conducted using a manually controlled dataset spanning fifty days. A first estimate of uncertainty budget is quantified following the principles outlined in the Guide to the Expression of Uncertainty in Measurement (GUM).

The Ground-Based Observations for Validation (GBOV, https://land.copernicus.eu/global/gbov), under the Copernicus Global Land Service, aims to establish a comprehensive database of ground-based land products and reference measurements. Evaluation and validation of the QC and uncertainty processing methods are performed within two GBOV PAR quantum sensor networks. The first network, situated in Hainich National Park, Germany, within an old-growth beech forest, comprises a single above-canopy node. The second network, located at the Valencia Anchor Station, Spain, within a Mediterranean vineyard, incorporates multiple above-canopy sensors.

We anticipate presenting the outcomes of our investigation during the forthcoming conference.

 

239 The African Greenhouse Gas Budget (2010-2019): a synthesis of the most recent data and models

Oral

Yolandi Ernst1*, Sally Archibald1, Heiko Balzter2, Frederic Chevallier3, Philippe Ciais3, Carlos G Fischer4, Benjamin Gaubert5, Thomas Higginbottom6,7, Steven Higgins8, Shakirudeen Lawal9, Fabrice Lacroix10, Ronny Lauerwald11, Mauro Lourenco1,12, Carola Martens13,14, Anteneh G Mengistu15, Lutz Merbold16, Edward Mitchard17, Mthokozisi Moyo1, Hannah Nguyen18, Michael O&apos;Sullivan19, Pedro Rodriguez-Veiga20,2, Thais Rosan19, Judith Rosentreter21, Casey Ryan17, Simon Scheiter13, Stephen Sitch19, Nicola Stevens1,22, Torbern Tagesson23,24, Hanqin Tian25, Mengjia Wang26,27, Joel S Woon28, Bo Zheng29, Yong Zhou30, Robert J Scholes1

1University of the Witwatersrand, Johannesburg, South Africa. 2University of Leicester, Leicester, United Kingdom. 3Université Paris-Saclay, Gif-sur-Yvette, France. 4Cornell University, NY, USA. 5NSF National Center for Atmospheric Research (NCAR), Boulder, CO, USA. 6Airbus Defence and Space, Surrey, United Kingdom. 7University of Manchester, Manchester, United Kingdom. 8University of Bayreuth, Bayreuth, Germany. 9North Carolina State University, NC, USA. 10University of Bern, Bern, Switzerland. 11Université Paris-Saclay, Palaiseau, France. 12Wild bird trust, Johannesburg, South Africa. 13Senckenberg Biodiversity and Climate Research Centre (SBiK-F), Frankfurt am Main, Germany. 14Goethe University Frankfurt am Main, Frankfurt am Main, Germany. 15Finnish Meteorological Institute, Helsinki, Finland. 16Integrative Agroecology Group, Agroscope, Zurich, Switzerland. 17University of Edinburgh, Edinburgh, United Kingdom. 18King&apos;s College London Strand, London, United Kingdom. 19University of Exeter, Exeter, United Kingdom. 20Sylvera Ltd, London, United Kingdom. 21Southern Cross University, Lismore, NSW, Australia. 22University of Oxford, Oxford, United Kingdom. 23Lund University, Lund, Sweden. 24University of Copenhagen, Copenhagen, Denmark. 25Boston College, Chestnut Hill, MA, USA. 26Zhengzhou University, Zhengzhou, China. 27Universit´e de Bordeaux, Villenave d&apos;Ornon, France. 28University of Liverpool, Liverpool, United Kingdom. 29Tsinghua University, Beijing, China. 30Utah State University, Logan, UT, USA

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

We developed a comprehensive African greenhouse gas (GHG) budget over the 2010-2019 time period as part of the REgional Carbon Cycle Assessment and Processes Phase 2 (RECCAP2). We incorporated bottom-up process-based models, data-driven remotely sensed products, and national GHG inventories in comparison with top-down atmospheric inversions, inclusive of lateral fluxes. For fluxes of particular importance in Africa (e.g. termites, herbivores and fire), we derived emission estimates from novel methodologies. We further constrained global woody biomass change products with high-quality regional observations. Net ecosystem exchange switched from a small sink of −0.61 ± 0.58 PgCyr−1 in RECCAP1 (1985-2009) to a small source in RECCAP2 at 0.16 (-0.52/1.36) PgCyr-1. Net bottom-up estimates of CO2 emissions were 1.6 (-0.9/5.8) PgCO2yr-1, net CH4 were 77 (56.4/93.9) TgCH4yr-1 and net N2O were 2.9 (1.4/4.9) TgN2Oyr-1, showing similar trends to top-down atmospheric inversions. Land use change emissions (0.5 PgCyr-1) are still higher than fossil fuel emissions (0.4 PgCyr-1), and both are increasing. Africa still contributes ~4% of the global fossil fuel emissions, but emits nearly 40% of the global emissions from land use. Overall, the continent contributes 3-5% of the growing amount of GHGs in the atmosphere. Uncertainty remains high despite improved methodology, highlighting the need for increased efforts to address Africa-specific data gaps and develop models that integrate Africa-specific processes. Nevertheless, this budget provides a baseline against which to assess policy and intervention effectiveness, and a tool to identify sectors and regions that should be prioritised for improving livelihoods and increasing carbon storage.

 

240 GAW-qc: A data science-based dashboard to promote near-realtime quality control of atmospheric composition measurements

Oral

Yuri Brugnara*, Martin Steinbacher, Lukas Emmenegger

Empa, Dübendorf, Switzerland

Session 16. Continuous Learning in a changing world - Teaching and learning novel tools & methods used for measurement techniques’, data & policy

The Global Atmosphere Watch (GAW) Programme of the World Meteorological Organization coordinates a worldwide network of ground-based in-situ monitoring stations that provide reliable scientific data on the chemical composition of the atmosphere. In the framework of the GAW Programme, the Quality Assurance/Scientific Activity Centre at Empa has developed an interactive dashboard based on data science to support station operators in timely detecting issues in their in-situ measurements of carbon dioxide, carbon monoxide, methane, and ozone concentration.

The application (GAW-qc), currently in beta testing, makes use of a mixture of purely data-driven and hybrid anomaly detection techniques. It exploits historical measurements as well as the archive of physics-based numerical forecasts by the Copernicus Atmosphere Monitoring Service (CAMS). The representativeness of the latter is improved through machine learning, resulting in more reliable predictions for the target station.

GAW-qc allows station operators to upload their latest measurements, visualize the data with different temporal aggregations, and easily detect anomalous values using just their internet browser. First case studies indicate that this process can facilitate the timely detection of malfunctionings in the analytical setup and reduce the ingestion of erroneous data into the international data repositories. It may become a game-changer towards reliable, comparable and traceable world-wide datasets in the field of air quality and greenhouse gases.

 
 241 Do N2O fluxes and N2O production processes differ under different grassland management (overseeding legumes vs. organic fertilization)?

Oral

Iris Feigenwinter1*, Lukas Hörtnagl1, Elizabeth Verhoeven2, Charlotte Decock3, Paul Magyar4, Roland A. Werner1, Moritz F. Lehmann5, Nina Buchmann1

1ETH Zurich, Zurich, Switzerland. 2Oregon State University, Corvallis, USA. 3Cal Poly, San Luis Obispo, USA. 4Empa, Dübendorf, Switzerland. 5University of Basel, Basel, Switzerland

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Nitrous oxide (N2O) is an important greenhouse gas, and agriculture is the main contributor to anthropogenic N2O emissions. To mitigate N2O fluxes from agricultural areas, the underlying N2O production processes and their environmental constraints need to be better understood, and the effects of different management strategies on N2O production need to be tested.
 Thus, our aims were 1) to investigate the effect of overseeding legumes versus slurry N fertilization on N2O fluxes and 2) to compare N2O production processes under the two grassland N fertilization strategies. We conducted a N2O-mitigation experiment at a temperate grassland over five years, replacing N inputs via organic N fertilization (slurry) with biological N2 fixation via overseeding legumes (clover). N2O fluxes were measured with eddy covariance, while N2O production processes were assessed using a stable isotope approach. The site preference (SP, intramolecular distribution of 15N within N2O) served as indicator for nitrification and denitrification. N2O fluxes showed net N2O emissions on the annual scale, which were lower in the oversown legume parcel (3.2 kg N2O-N ha-1 yr-1) compared to the parcel fertilized with slurry (5.8 kg N2O-N ha-1 yr-1; 4-year average). SP values (7.5±4.9‰; average±SD, n=111) did not differ between parcels, and indicated denitrification as the main N2O production process, independent of grassland management. Replacing organic fertilization with overseeding legumes proved to be a suitable N2O mitigation measure, with further environmental benefits such as reduced nitrogen leaching, albeit with a trade-off for carbon sequestration.


242 A high-resolution atmospheric inversion framework for CO2 observations in Paris using GRAMM/GRAL

Oral

Robert Maiwald1*, Anna Sommani1, Jani Strömberg2, Leena Järvi2, Michel Ramonet3, Olivier Laurent3, Carla D'Angeli3,4, Thomas Lauvaux3,4, Sanam N. Vardag1,5

1Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany. 2Institute for Atmospheric and Earth System Research, Faculty of Science, University of Helsinki, Helsinki, Finland. 3Laboratoire des Sciences du Climat et de l’Environnement, LSCE, UMR CNRS-CEA-UVSQ, IPSL, Gif-sur-Yvette, France. 4Groupe de Spectrométrie Moléculaire et Atmosphérique GSMA, Université de Reims-Champagne Ardenne, UMR CNRS, Reims, France. 5Heidelberg Center for the Environment (HCE), Heidelberg University, Heidelberg, Germany

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Cities are carbon dioxide (CO2) emission hotspots and exhibit multiple different CO2 sources from various sectors in close vicinity. For a city to implement effective mitigation measures, the sector-specific emissions need to be known and changes in the emissions must be monitored on highest possible resolution.  

We present a framework to estimate the emissions of urban areas. Atmospheric transport of CO2 is simulated on high resolution using the model GRAMM/GRAL. By assuming hourly steady-state conditions and applying a match-to-observation algorithm, the model can simulate atmospheric transport with a horizontal resolution of 10m x 10m for cities. Conducting a Bayesian inversion approach described in Vardag and Maiwald, 2024, urban CO2 emission can be estimated.  

We apply the framework in Paris, France. The city is a European CO2 emission hotspot and has set-up an ambitious climate plan with the goal to become completely carbon neutral by 2050. For the framework, prior information about the emissions is taken from inventories (TNO) and atmospheric CO2 measurements are provided by ICOS Cities (Horizon Europe, PAUL project). We compare measured and simulated CO2 enhancements and discuss implications for CO2 emission estimation. We give an outlook on current limitations and further development of emission estimates.  

Vardag, S. N. and Maiwald, R.: Optimising urban measurement networks for CO2 flux estimation: a high-resolution observing system simulation experiment using GRAMM/GRAL, Geosci. Model Dev., 17, 1885–1902, https://doi.org/10.5194/gmd-17-1885-2024, 2024.


243 Three years of Eddy covariance measurements of a tropical forest in the Congo Basin.

Poster

Roxanne Daelman1*, Marijn Bauters1, Lodewijk Lefevre1, Thomas Sibret1, José Mbifo2, Hans Verbeeck1, Pascal Boeckx1

1Ghent University, Ghent, Belgium. 2INERA, Yangambi, Congo, the Democratic Republic of the

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

The CongoFlux climate site in the Yangambi UNESCO biosphere reserve (0°48’52.0N, 24°30’08.9”E) hosts the first Eddy Covariance (EC) flux tower in the central Congo Basin. The site, recently labeled as an ICOS associated ecosystem station, was built in 2020 to address the lack of observations of the tropical forest ecosystems in Central Africa. We aim to quantify the net ecosystem exchange (NEE) and the water use efficiency (WUE) of the tropical forest in the footprint of the tower. A set of meteorological and hydrological data is recorded that could explain the seasonal patterns of NEE and WUE. In addition also soil respiration, stem respiration and gas exchange on leaf level scale are measured. Processing EC data still remains a challenge in the tropics. Tall vegetation and frequent low turbulent conditions call for attention to the storage correction term. Multiple set ups on the site were used to study the best way to handle the nighttime buildup of CO2 in the canopy. The threshold for the friction velocity filtering, needs to be selected with care to minimize the influence of the frequent low turbulent conditions, while at the same time minimizing the amount of data that needs to be filtered out. Power cuts and data filtering result in many and sometimes large data gaps, which increase the importance of accurate gap filling techniques. We here present three years of processed EC data together with the challenges of an EC station in the tropical forest of the Congo basin.


244 Soil CO2 emission from different agricultural management practices

Poster

MANUEL ACOSTA*, Lukáš Kokrda, Marian Pavelka

Global Change Research Institute, CAS, Brno, Czech Republic

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

In agricultural cropping systems, the larger part of the carbon is stored in the soil. Improving agricultural practices has great potential to increase the amount of carbon sequestered in cropland soil. Promising approaches in recent years are changes in management practices and biochar application. We conducted soil CO2 emissions (SCO2) measurements on a maize (Zea mays L.) plantation using the chamber technique during three vegetation seasons (2021-2023) with different management practices (conventional tillage, no-tillage, biochar application and no-biochar application). Our preliminary results showed that In all the investigated management, SCO2 showed a good correlation with soil temperature but not with soil water content. The highest SCO2 (7.6 mmolCO2m-2s-1) was measured at the no-till management while the lowest measured SCO2 (0.7 mmolCO2m-2s-1) was at the conventional management. Regarding biochar management practices the highest SCO2 was measured at the conventional management without biochar application while the lowest measured SCO2 was on no-till with biochar application. The variances of the random effects determined by a model showed that there was more variance among positions at different management than between measurement campaigns. Furthermore, a mixed-effect model was used to assess the driving ecosystem factors of SCO2. The model shows that no-tillage management has significantly higher SCO2 emissions than conventional tillage management. Nevertheless, in our study on maize plantation, the conventional tillage without biochar application management showed a higher averaged SCO2 over the whole experiment period, indicating that this kind of soil agricultural management is not appropriate when SCO2 is taken into account.    


245 ICOS Norway – a tool to verify Norwegian emission reduction

Poster

Siv K Lauvset*

NORCE, Bergen, Norway

Session 13. In situ data for climate and other environmental services and policy support

ICOS-Norway brings together the leading Norwegian institutes for greenhouse gas observations in the three Earth system domains atmosphere, ocean, and terrestrial ecosystems, providing world-leading competence, which is integrated into one jointly operated infrastructure. This provides Norway with a state-of-the-art research infrastructure embedded in European and global efforts. This allows us to provide accurate and accessible data on the Norwegian carbon balance, as well as operate an inverse modelling system to provide integrated top-down assessments at regional scale, across the land, ocean, and atmosphere. ICOS-Norway thus improves our understanding of how greenhouse gas emissions move in the Earth system, and is an essential element in the knowledge base underpinning the Norwegian path towards a net-zero emission society. Here we present the main products provided by ICOS-Norway, as well as future plans.  


246 A deep learning approach for extracting coal power plant and industrial sector operations using satellite images for GHG and pollutant emissions estimation in India

Poster

Clément Goldmann1*, Chuanlong Zhou1, Philippe Ciais1, Martin Brandt2, Kushal Tibrewal1, Sugandha Arora3, Fabian Gieseke3, Anthony Rey-Pommier1, Harish Phuleria4, Arnab Jana4

1Laboratoire des Sciences du Climat et de l’Environnement, IPSL CEA CNRS UVSQ, Gif-sur-Yvette, France. 2University of Copenhagen, Copenhagen, Denmark. 3University of Münster, Münster, Germany. 4Indian Institute of Technology Bombay, Mumbai, India

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

Monitoring  facility-level activity for power plants and industrial sites is critical for pollutant and greenhouse gas emission management and mitigating, as well as climate change impacts. India is one of the largest country with coal-powered plants, which contributed approximately 71% of the country's total CO2 emissions in 2021, roughly 1627.306 Mt CO2, according to the International Energy Agency (IEA). Industrial Processes and Product Uses represent 263 Mt CO2 in 2019, mostly drive by cement and steel production. 

By harnessing real-time, high-resolution data our approach uniquely merges diverse datasets to deliver unparalleled detail in monitoring emissions at the facility level.We automatically extract coal plant-level activity based on water vapor and smoke plumes detected at individual chimneys or condensation towers from high-resolution satellite imagery (Sentinel-2 and the PLANET constellation), based on deep learning models. The power, cement and steel plants location data is collected from the Global Energy Monitor (GEM). Additional annotations on chimney locations are collected from the Open Street Map. We then validate the extracted activity with energy production reports from the Indian National Power Portal (NPP). Activity detection will be compared with NOx emissions from power plants based on Sentinel-5P TROPOMI data.

Our methodology also seeks to extend its application to the broader industrial sector, including cement and steel plants, or numerous brick kilns across India, a notable source of emissions. This approach creates new datasets for environmental monitoring and detailed temporal emissions profiles of energy and industry sectors emission.


247 Characterizing background errors in IFS greenhouse gas emission inversions

Oral

Auke Visser1*, Nicolas Bousserez1, Anna Agusti-Panareda2, Luca Cantarello1, Ernest Koffi1, Panagiotis Kountouris1, Marc Guevara3, Thomas Kaminski4, Ingrid Super5, Tilman Hohenberger5, Michael Voßbeck4, Peter Rayner4, Marko Scholze6, Carlos Gomez6, Richard Engelen1

1European Centre for Medium-Range Weather Forecasts, Bonn, Germany. 2European Centre for Medium-Range Weather Forecasts, Reading, United Kingdom. 3Barcelona Supercomputing Center, Barcelona, Spain. 4The Inversion Lab, Hamburg, Germany. 5Netherlands Organization for Applied Scientific Research, Utrecht, Netherlands. 6Lund University, Lund, Sweden

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The provision of timely and reliable anthropogenic greenhouse gas (GHG) emission estimates is crucial to monitor compliance with emission reduction targets set in international climate agreements. To prepare for a new Copernicus service focused on operational monitoring of anthropogenic GHG emissions (entitled the CO2 Monitoring and Verification Support system, or CO2MVS), the Integrated Forecasting System (IFS) is currently being extended to allow for inverse modelling of CO2 emissions and co-emitted species (CO, NOx). A critical step in this development is the definition of the prior error covariance matrix (B matrix) for GHG fluxes, which enables the propagation of information in space, time and across species within this emission inversion system. 

In this presentation, we will introduce developments in the IFS B matrix for the CO2MVS and discuss a methodology to derive B matrix parameters (spatial and temporal error correlation scales), focusing on two examples. First, we will show the derivation of B matrix parameters for biogenic CO2 fluxes (gross primary production and ecosystem respiration), obtained from a pseudo-climatology of residuals between IFS simulations and an observational product upscaled using remote sensing data and machine learning (FLUXCOM). We will highlight the impact of B matrix modifications on derived biogenic fluxes, and show an evaluation based on atmospheric CO2 observations. Second, we will discuss preliminary results for the derivation of B matrix parameters for anthropogenic emissions, based on an ensemble of global, daily COemissions obtained by propagating parameter uncertainties in an emission model, and a dataset of cross-species emission error correlations. 


248 Recent Developments in Satellite and Airborne Remote Sensing of Methane Emissions

Oral

Hartmut Boesch*, Jakob Borchardt, Heinrich Bovensmann, Michael Buchwitz, John Burrows, Konstantin Gerilowski, Michael Hilker, Sven Krautwurst, Stefan Noël, Max Reuter, Oliver Schneising, Streffen Vanselow

University of Bremen, Bremen, Germany

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

The use of satellite remote sensing of methane columns for constraining the global distribution and trends of methane sources and sinks is now well established with more than two decades of satellite observations from SCIAMACHY, GOSAT/-2 and TROPOMI. The impact of satellites has been particular noticeable for regions poorly observed by surface networks such as the Tropics. Satellite observations are also a playing an increasingly important role for identification and quantification of anthropogenic emission sources. TROPOMI data has been successfully used to highlight previously unknown or poorly characterised emission sources thanks to its global mapping capabilities albeit with only km- resolution. This is complemented by observations from a fleet of hyper/multispectral satellite instruments and aircraft imaging instruments that can observe emission plumes with resolutions of tens to hundreds of meters but with limited coverage.  

In this presentation, we will give an overview over the IUP-Bremen TROPOMI retrieval of methane and its recent improvements. We will discuss how TROPOMI is used to identify persistent emission sources and to obtain estimates of their emission. TROPOMI observations also provides guidance for detailed aircraft campaigns and targeted observations by high-resolution satellites. As example we will show the recent deployment of the IUP-Bremen aircraft imaging spectrometer MAMAP-2DL to Eastern Australia as part of the UNEP-IMEO Programme to determine methane emissions from coal mining. We will also discuss how we use high-resolution satellite instruments such as PRISMA, ENMAP and EMITS to observe and quantify methane point source emission and highlight limitations of the  retrieval methods.


249 Set-up of the first EM27/SUN measurement site in the Po Valley (Italy)

Poster

Elisa Castelli1*, Andrè Achilli1,2, Claudio Campenni1, Francescopiero Calzolari1

1CNR-ISAC, Bologna, Italy. 2University of Bologna, Bologna, Italy

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

The Po Valley is one of the most important economic regions in Italy. Most of the Italian industries are located here and it is also the Italian agricultural heartland. However, due to its peculiar conformation, it is also known as one of the most polluted regions in Europe. Greenhouse Gases  (GHG) monitoring in the Po Valley is thus of strategic importance.

GHG can be monitored from ground with both in-situ and remote sensing techniques. In particular, ground-based remote sensing measurements can provide valuable total column datasets for the study of atmospheric phenomena and satellite validation.

In recent years, a network of portable FTIR spectrometers, the COCCON (Collaborative Carbon Column Observing Network), has been developed to complement measurements from high resolution FTIR compliant with TCCON (Total Carbon Column Observing Network) and NDACC (Network for the Detection of Atmospheric Composition Change) networks. The instrument used in the COCCON network is the Bruker EM27/SUN.

In the frame of the EMM project, we recently acquired an EM27/SUN instrument. Here, we show the first results we get from the portable spectrometer located in Bologna (Italy) at CNR-ISAC premises, in the Po Valley, and describe its set-up. 

we thank the support of the Next Generation EU funds within the National Recovery and Resilience Plan (PNRR), Mission 4 - Education and Research, Component 2 - From Research to Business (M4C2), Investment Line 3.1 - Strengthening and creation of Research Infrastructures, Project IR0000038 – “Earth Moon Mars (EMM)”. EMM is led by INAF in partnership with ASI and CNR
 

250 Climate change communication in a time of information abundance

Oral

Fran Laurik*

University of Antwerp, Antwerp, Belgium

Session 15. Science communication and outreach to increase the impact of climate research

Climate change is most likely one of the research fields that both requires and benefits most from science communication. Despite today’s information abundance on the topic, it has never been more difficult for a non-expert to differentiate relevant data from political stunts. Funding agencies and society itself are therefore actively demanding for reliable, accessible and understandable communication from researchers.

Despite the sense of urgency, researchers often lack time, expertise and a platform hindering them to communicate to a general audience. Also University of Antwerp (Belgium) faces these challenges. In order to facilitate science communication, three trajectories were developed. First trajectory focuses on the low hanging communication fruits, i.e. participation at science fairs and on site communication. Second trajectory aims for active interaction with local policy organizations. More often than not these organizations face similar challenges researchers aim to tackle. Engaging with policy makers allows to combine research and policy questions and streamline experiments so they can offer benefits on local scale. The third trajectory aims for the integration of climate research in primary and secondary schools. With the startup KlimaatLINK, University of Antwerp established a dedicated climate education project. KlimaatLINK focusses on combining and translating knowledge from state-of-the-art research projects to educational packages that can directly be implemented in the classroom.

 

251 High-Resolution Regional Atmospheric CO2 Inversion: Integrating Data and Models for Carbon Budgets

Oral

Carla D'angeli1*, Thomas Lauvaux1, Charbel Abdallah1, Ke Che2, Michel Ramonet2, Morgan Lopez2, Hassan Bazzi3,4, Philippe Ciais2, Léonard Rivier2

1GSMA, Université de Reims Champagne-Ardenne, Reims, France. 2Laboratoire des Sciences du Climat et de l’Environnement (LSCE) / IPSL / CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France. 3Université Paris-Saclay, AgroParisTech, INRAE, UMR 518 MIA Paris-Saclay, Palaiseau, France. 4Atos France, Technical Services, 80 Quai Voltaire, Bezons, France

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Effective mitigation strategies hinge on the accurate assessment of carbon dioxide sources and sinks, the largest greenhouse gas contributing to human-made climate change. Leveraging information from atmospheric concentration observations in combination with inventories and biogeochemical models can provide national-scale estimates of biogenic fluxes and fossil fuel emissions, but current systems do not provide robust estimates over space and time. By integrating the ICOS atmospheric station network within a high-resolution atmospheric model via an inverse approach, we present here a high-resolution inversion system able to quantify CO2 fluxes across continental France, illustrating the methodology and its performances for the year 2022.

Our inversion system aims to optimize CO2 flux estimates at higher spatiotemporal resolutions over France (3km, hourly). The Lagrangian Particle Dispersion Model (LPDM) developed running in backward-in-time model, driven by meteorological inputs from a 3-km run of the Weather Research Forecast Model (WRF), establishes the transport of CO2 molecules. Employing a Bayesian inversion technique, we optimize prior CO2 flux estimates by integrating tower footprints and ICOS atmospheric measurements into a newly-developed inversion framework.

We present the model performance with the evaluation of the inverse flux anomalies for 2022. We assess the capacity of the inversion on leveraging information from atmospheric measurements to enhance our understanding of regional carbon cycling processes, particularly the biogenic component during an intense summer heat wave. We propose to constrain the fluxes by including the incorporation of carbon-14 flask measurements to distinguish fossil emissions from biogenic fluxes and an optimal deployment of ICOS stations.
 

252 Nitrous oxide emissions following organic-based soil amendments in comparison with mineral fertilizer in walnut orchard (Juglans regia L.)

Poster

Camilla Chieco1*, Daniela Famulari1, Lorenzo Fiorini1, Elena Baldi2, Maurizio Quartieri2, Lorenzo Brilli3, Federico Carotenuto1, Vasileio Voulgaridis2, Moreno Toselli2, Marianna Nardino1

1CNR-IBE, Bologna, Italy. 2University of Bologna, Bologna, Italy. 3CNR-IBE, Florence, Italy

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Among the non-CO2 greenhouse gases, nitrous oxide (N2O) is one of the most important, with the agricultural sectors represents its largest source worldwide. Understanding how different type and amount of fertilizers can determine different N2O emission patterns and magnitude may help to improve agronomic management in the perspective of both agricultural production optimization (i.e., reduction of N input costs) and climate mitigation (i.e., emissions reduction). In this context, an experimental field campaign to evaluate N2O emissions from soil based on different type and amount of fertilizers is currently ongoing in a walnut trees (Juglans regia L.) plantation in Bondeno (Emilia Romagna, Italy). Specifically,  mineral fertilizer (1) municipal organic waste compost (2), sewage sludge compost from agro-food waste (3), and biochar (4) were tested. Soil amendments were added at the beginning of the season within the row, while mineral fertilizer was added twice 30 days apart. Soil N2O fluxes were measured using a portable N2O trace gas analyzer (LI-7820 N2O /H2O, Li-Cor) connected with an automated soil chamber (LI-8200-01S Smart Chamber, Li-Cor) along the whole growing season. Furthermore, monthly data of soil TKN, mineral N (NH4+ and NO3-) and moisture were also measured. Despite the experiment is still running, preliminary results suggested as different fertilization treatments provided differences in magnitude of cumulated soil N2O emissions.
 

253 Limitations on the accuracy of point-source emission estimation due to atmospheric turbulence

Poster

Michał Gałkowski1,2*, Julia Marshall3, Blanca Fuentes Andrade4, Christoph Gerbig1

1Max Planck Institute for Biogeochemistry, Jena, Germany. 2AGH University of Kraków, Kraków, Poland. 3Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germany. 4University of Bremen, Bremen, Germany

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

Monitoring of greenhouse gas emissions is a critical part of climate mitigation. Without timely, accurate and precise information on the policy implementation status, potential diversions from the plan cannot be identified and acted upon in time. Emission estimation methods based on direct space- or airborne observations hold much promise for the provision of relevant data across policy-relevant scales, especially when applied to the strongest sources of greenhouse gases, like coal power plants, megacities or industrial sites. 

Using the high-resolution WRF-GHG framework set over the largest point-like CO2 emitter in Europe, we demonstrate how atmospheric turbulence affects the plume structure, limiting the accuracy of estimated emissions using the cross-sectional mass-flux method. Through a novel application of temporally-tagged tracers, we show that the apparent CO2 emission variability is due to turbulence at the point of emission and then propagated across distances significantly longer than PBL turbulent scales.

Unless the discussed effects can be taken into account when planning, executing and interpreting measurements, they will have detrimental consequences for emission monitoring. It is worth noting that the presented results are of general nature and will affect attempts to quantify emissions of any pollutant for which similar estimation techniques are applied, including CO2, CH4, NOx and others.


254 A paired flux tower-dendrometer network to investigate forest carbon from assimilation to allocation to tree growth

Oral

Mukund Rao1*, Troy Magney2, Ivan Janssens3, Josep Peñuelas1

1CREAF, Barcelona, Spain. 2UC Davis, Davis, USA. 3Universiteit Antwerpen, Antwerpen, Belgium

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Carbon assimilated through photosynthesis is distributed among various plant processes with only a fraction allocated to tree secondary growth. This woody biomass constitutes a long-term carbon pool on the landscape. The allocation of carbon to tree growth, respiration, and reproduction is not constant but highly dynamic. Understanding the post-assimilation dynamics of carbon, particularly its allocation to tree growth, is crucial to comprehending the potential of forests as long-term carbon sinks. To address this, we propose the utilization of dendrometers, which are sensors mounted on tree trunks and capable of monitoring micrometer-scale changes in tree radius due to growth and hydration. In this presentation, we introduce a collaborative paired flux-tower dendrometer network comprising 20 locations across 14 countries, encompassing tropical sites in Costa Rica and Mexico, as well as temperate and boreal sites in Europe and North America. At each site, tree dendrometers are co-located within the footprint of eddy covariance tower-based ecosystem carbon fluxes and tower-based remote sensing measurements (e.g. PhenoCams, hyperspectral and SIF). We will share preliminary results from diverse ecosystems, focusing on the timing and manner in which forests assimilate carbon through photosynthesis, allocate it to above-ground growth, thus creating a long-term carbon sink, and elucidate the influence of climate and water availability on these processes. As ICOS formalises its plans to install dendrometers across all forested sies, we extend an invitation to community members who currently have or wish to establish paired flux towers and dendrometers at their sites to join, collaborate, and contribute to this synthesis.


255 Understanding High Arctic Tundra vegetation dynamics: Insights from a multi-year study on carbon fluxes and carbon isotope composition

Poster

Carlotta Volterrani1,2*, Olga Gavrichkova1,3, Emanuele Pallozzi4,3, Enrico Brugnoli1, Angela Augusti1

1Institute of Research on Terrestrial Ecosystems (IRET), National Research Council of Italy (CNR), Porano, Italy. 2Cà Foscari University of Venice, Venezia, Italy. 3National Biodiversity Future Center (NBFC), Palermo, Italy. 4Institute of Research on Terrestrial Ecosystems (IRET), National Research Council of Italy (CNR), Monterotondo, Italy

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Arctic terrestrial ecosystems undergo serious alterations due to climate change, with both arctic greening and browning being reported as potential response trends. In order to improve knowledge on high arctic tundra vegetation dynamics and evaluate its consequences for the C balance, Dryas octopetala and Salix polaris were considered during 3 years of measurements, being among the most abundant and representative species in Svalbard Islands. Experimental design was based on measurements of CO2 fluxes - ecosystem respiration (Reco), gross primary production (GPP) and net ecosystem exchange (NEE) - environmental parameters (soil temperature, moisture, photosynthetically active radiation (PAR)) and plant stable isotope composition (δ13C). A common response patterns for C fluxes, could be highlighted across years, for both species. They were acting as C sink, which strength grew across years. Moreover, leaf δ13C showed a more negative value for D. octopetala compared to S. Polaris (-30,48‰ versus -28,71‰, respectively, as 3-years-avarage). NEE was most sensitive to PAR variation rather than to temperature and soil humidity changes. Reco instead increased with soil temperature and correlated with vegetation δ13C highlighting substantial impact of vegetation to this flux. Changes in cloudiness and soil temperature will be the primary factors affecting the C balance of high arctic tundra communities, although the impact of plant species dynamics should be considered.


256 Bottom-up evaluation of greenhouse gases (CO2, CH4, N2O) at regional scale

Poster

Akihiko Ito*

University of Tokyo, Tokyo, Japan

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Comprehensive budget evaluations of greenhouse gases (CO2, CH4, N2O) are unequivocally important for the accomplishment of the mitigation goal of the Paris Agreement. In addition to atmospheric monitoring using satellite-to-ground platforms (top-down), independent assessment using a bottom-up approach, which aggregates ground-level sinks and sources, is necessary to give an independent validation. This study demonstrates a bottom-up evaluation system of greenhouse gas budgets at the country to global scales, which is developed for the Environmental Research Fund “S-22: Comprehensive Study and Monitoring of Long-lived Greenhouse Gases and Short-lived Climate Forcers toward Mitigation of Climate Change”, funded by the Ministry of the Environment, Japan. For each gas, natural and anthropogenic greenhouse gas sources and sinks are evaluated using geographic data, emission inventories (e.g., EDGAR), biogeochemical models (e.g., VISIT), and satellite products (e.g., GFED). For example, total CO2 budget is evaluated for net ecosystem production (photosynthesis – respiration) of natural ecosystems, land-use emissions, wildfire, fossil fuel mining, industrial and municipal sectors, waste management, and agricultural sectors. The method was successfully applied to the CH4 budget of Asia region (Ito et al., 2023, 10.1029/2023GB007723) and to the N2O budget (Ito and Nishina, submitted). The method clarifies spatial distribution and temporal variation of individual and combined sources and sinks, enabling us to specify emission hot spots and remarkable sectors for the mitigation target. This presentation shows the results of the Asian greenhouse gas budget during 1970–2022 using the updated bottom-up approach.


257 Complex spatial and temporal patterns of greenhouse gas emissions central London, UK: hotspots and long-term trends.

Oral

Carole Helfter1*, Neil Mullinger1, Karen Yeung1, Janet Barlow2, Eiko Nemitz1

1UKCEH, Edinburgh, United Kingdom. 2University of Reading, Reading, United Kingdom

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

We report on over a decade of measurements of greenhouse gas (GHG) fluxes from a tall tower in central London, UK. Measurements of carbon dioxide (CO2) and methane (CH4) by eddy-covariance from atop the 190 m BT Tower (51°31’17.4 N, 0°8’20.04 W) began in late 2011; nitrous oxide (N2O), carbon monoxide (CO), nitrogen dioxide (NO2) and ethane (C2H6) have been measured since 2021. Land-use is very diverse within the flux footprint of the tower, with a juxtaposition of commercial and residential areas, transport hubs as well as extensive green spaces. This results in spatially heterogenous activity levels with distinct temporal dynamics, which modulate the fluxes at timescales ranging from hourly to inter-seasonal.  

The measured CO2 (2012-2019 mean +/- standard deviation: 41.0 +/- 2.4 kton.km-2.y-1) budget validates the bottom-up estimates from the London Atmospheric Emissions Inventory (LAEI; 38.7 kton.km-2.y-1 for CO2), demonstrating that urban sources of this gas are well known. In contrast, our measurements reveal that CH4 emissions are underestimated by ca. a factor of 2 (measured: 69.9 +/- 3.3 ton.km-2.y-1; LAEI: 29.0 ton.km-2.y-1). We attribute this discrepancy in part to an underestimation by the inventory of leaks in the natural gas distribution network, but observed hotspots of CH4 in areas of low C2H6 (a tracer for fossil fuel CH4 emissions) fluxes could indicate emissions of biogenic origin. Finally, despite a decrease in emissions in 2020 and 2021 due to Covid-19 restrictions and the introduction of an ultra-low emissions zone in 2019, we observed little inter-annual variability in CO2 and CH4.


258 Mapping CO2 fluxes of drained fen meadows in the Netherlands with machine learning

Poster

Laura van der Poel*, Laurent Bataille, Ronald Hutjes, Bart Kruijt, Wietse Franssen, Jan Biermann, Hong Zhao, Ruchita Ingle

Wageningen University, Wageningen, Netherlands

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

In the Netherlands, emissions from drained organic soils amount to around 3% of all national greenhouse gas emissions. Following the 2019 mitigation target, the Netherlands Research Progamme on Greenhouse gas dynamics in Peatlands and organic soils (NOBV) investigates the efficiency of proposed mitigation measures, and aims to enhance the understanding and quantification of drivers of regional peatland emissions. Our study is in line with NOBV’s objectives and aims to provide regional CO2 balances for the three main fen meadow areas in the Netherlands.

As part of the NOBV campaigns, Eddy Covariance (EC) measurements are taken from a low-flying aircraft since 2020. Additionally, a large EC tower network has been established with both stationary and mobile systems, encompassing 25 measurement sites. 

In this study, we combine airborne and tower CO2 flux data, to make use of their different strengths: spatial heterogeneity and temporal continuity, respectively. We use footprint analysis to extract the corresponding spatial information from maps, remote sensing, and outputs of several soil and water models. Using this data, we train a boosted regression tree (BRT) machine learning algorithm. Feature selection and hyperparameter tuning are applied as model optimization techniques, and subsequently Shapley values are used to interpret the model’s outputs. We will present the found relationships with e.g. groundwater level, as well as high resolution modelled CO2 flux maps from which we estimate daily, monthly and yearly CO2 balances. 


259 Eddy covariance GHG fluxes from grasslands on mineral and drained organic soils in eastern Finland

Oral

Narasinha Shurpali1*, Olli Peltola2, Tero Toivonen1, Samuli Launiainen2, Janne Rinne2, Mikko Järvinen1, Perttu Virkajärvi1

1Natural Resources Institute Finland, Kuopio, Finland. 2Natural Resources Institute Finland, Helsinki, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Finland, with a predominantly boreal climate, is known for its milk production with an average yield of 8888 kg per cow in 2022. Grass-based production could be the key to sustainable milk and beef production. In Finland, grass is the main feed for milk and beef cattle. As a perennial plant, grass is almost the only crop plant that has the potential of preserving soil carbon. Milk and beef production are tightly connected, and nearly 80% of the Finnish beef production originates from the milk chain. The Finnish soils can be roughly categorized into two categories: mineral and organic soils. Mineral soils are typically well-drained and have a low organic matter content, whereas organic soils are characterized by high organic matter content and high-water retention capacity and these differences have a pivotal role in ecosystem-atmosphere greenhouse gas (GHG) exchange. With this in view, the Natural Research Institute Finland has initiated a long-term GHG flux monitoring framework for a sustainable grassland management and agriculture across several agricultural research clusters in Finland. Continuous data on GHG fluxes from managed grasslands on different soil types are being collected using the eddy covariance technique since 2020. Here, we present seasonal and annual variability in GHG fluxes and their short-term responses on management and environmental variability from three grassland sites in eastern Finland during two complete study years (2022 and 2023).  


260 X-ray CT scanning for intra-seasonal tree biomass assessment: potential application for carbon allocation in forests

Poster

Kobe Happaerts1*, Bert Gielen1, Jan Van den Bulcke Van den Bulcke2, Matteo Campioli1

1University of Antwerp, Antwerp, Belgium. 2Universiteit Gent, Gent, Belgium

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Recent studies have questioned the general assumption of a strict correlation between seasonal wood growth vs. diameter the temporal decoupling of cell enlargement and cell wall thickening. However, studying these formerly named growth phases has proven to be challenging due to technical limitations especially for angiosperms. 

A new cutting edge technique (Lehnebach et al., 2021), High-resolution X-ray Computed Tomography (XμCT), has proven to enhance accurate estimating of relevant tree xylogenesis parameters in a range of tree species, wood anatomies and wood structures. In addition it, also enhances the of quantification of intra-annual biomass production dynamics was proven by Lehnebach et al. (2021). 

Seasonality of carbon uptake and biomass growth since carbon makes up a large part of biomass building blocks. Hence the potential of using XμCT to perform detailed studies on carbon allocation in trees and forest ecosystems. There is a direct link between XμCT-date and the density of scanned material. Seasonal stem circumference data and seasonal carbon fluxes can be assessed in parallel to seasonal stem biomass production based on XμCT-data. 

There is a great potential to disentangle the incorrectly assumed correlation between seasonality of wood growth (and C sequestration (GPP/NPP)) vs. seasonality of diameter increase with the knowledge gaps that will hopefully be filled using these new methodologies.  

After initial results have been verified a study across several ICOS sites will be setup to further investigate the effects of tree species, climatic conditions and forest management on carbon allocation in forests. 


261 Monitoring a pine stand by means of automated drone surveys

Poster

Maarten Op de Beeck*, Joke Van den Berge, Tim De Meulder, Jan Segers, Ivan Janssens

University of Antwerp, Antwerp, Belgium

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

In an upcoming project, the ICOS Class 1 forest station of Brasschaat (BE-Bra) will be monitored on a semi-continuous basis by means of automated drone surveys. A drone is being custom build for this purpose and will be equipped with a SIF sensor, a thermal camera and multiple hyperspectral cameras. The drone will carry out repeated, automated flights over the pine stand throughout the entire growing season. The data collected with the drone will be used for quantifying stand productivity, monitoring tree health, ground truthing of satellite data, and evaluating measurements from the fixed eddy covariance tower. At the time of writing this abstract, the drone is not yet operational. Test flights are expected to take place in the second half of 2024 and routine flights are expected to start at the beginning of the 2025 growing season.


262 Cyprus Atmospheric Observatory: Insights into Greenhouse Gas Monitoring in the Eastern Mediterranean and Middle East

Poster

Pierre-Yves QUEHE1*, Jean-Daniel Paris2,1, Mihalis Vrekoussis3, Constantina Rousogenous1, Michel Ramonet2, Michael Pikridas1, Jean Sciare1

1The Cyprus Institute, Climate and Atmosphere Research Center (CARE-C), Nicosia, Cyprus. 2Laboratoire des Sciences du Climat et de l’Environnement (LSCE), Gif sur Yvette, France. 3University of Bremen,Institute of Environmental Physics and Remote Sensing (IUP) & Center of Marine Environmental Sciences (MARUM), Bremen, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Cyprus, an island located in the Eastern Mediterranean and Middle East (EMME) region, stands as a natural laboratory for studying local and regional pollution characteristics, due to its proximity to three continents: Europe, Asia, and Africa. This is particularly important given that increasing anthropogenic greenhouse gas (GHG) emissions over the last decades in the EMME region, led to regional warming at a rate twice that of the global average. 

In response to the imperativeness of monitoring GHG’ spatial and temporal variability, the Cyprus Atmospheric Observatory inaugurated a GHG station in Ineia (INE), within the remote and natural Akamas peninsula located on the western coast of the island. INE aims to be integrated into the ICOS atmosphere network as a class 2 station. Analysis of air masses origin conducted with the Lagrangian FLEXPART model, denoted the predominant influence of the Eastern Mediterranean Sea, complemented by contributions from Turkey and Europe, with additional influences from Middle East and Africa, subject to seasonal shifts in wind patterns. The INE quartiles (Q1, Q2, and Q3) of the last year for CO2, CO, and CH4 are respectively: [418.5, 423, 426], [112.6, 123, 136] and [1988.5, 2002, and 2014]. Our measurements are compared with other GHG monitoring stations in the region, such as Finokalia and Lampedusa.

Across the island, various ICOS class instruments conduct short-term, campaign-based, and long-term measurements of GHG. Additionally, ongoing since 2019, long-term total-column GHG observations (XGHG) from the TCCON Nicosia serve as a satellite and model validation site.


263 Assessing the variations of Atmospheric Methane concentration across the state of Gujarat, India during 2020-22 using satellite data

Poster

Anurag Kandya*, Viral Patel, Shubham Kela

Pandit Deendayal Energy University, Gandhinagar, India

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Methane is a potent green house gas that has a warming potential far higher than Carbon dioxide. Despite its high warming potential compared to carbon dioxide, methane emissions, particularly from urban areas worldwide, are poorly understood. To partially address this gap, the present study utilizes a space-based remote sensing approach, employing data from the TROPOMI instrument aboard the Sentinel-5 precursor satellite. Over a three-year period from January 2020 to December 2022, the study assessed atmospheric methane concentrations across the state of Gujarat which is the 5th largest Indian state having a geographical area of 196,000 km2.

Findings reveal an average annual concentration increase of 0.69% during this period. Specifically, methane levels rose by 4.1 parts per billion (ppb) from 2020 to 2021 and by 21.9 ppb from 2021 to 2022. In 2021, methane levels increased in 77.1% of Gujarat, ranging from 0-20 ppb, while decreasing in the remaining 22.9%. However, in 2022, levels increased across the state, predominantly ranging from 10-35 ppb compared to 2021.Notably, the Dang district consistently exhibited the lowest methane concentration, attributed to its dense forest cover. Conversely, central Gujarat, including districts like Ahmedabad, Gandhinagar, Patan, and Kheda, displayed the highest concentrations. Junagadh, Botad, and Anand districts showed the highest annual increase rates. Overall, these findings are crucial for informing and enhancing the Methane Emissions Reduction Action Plan in Gujarat, aiding in climate change mitigation efforts.


264 Groundwater level control as GHG emission reduction option tested using eddy covariance for peatland in the Netherlands

Poster

Pascal Wintjen*, Arnoud Frumau, Pim van den Bulk, Harmen van Mansom, Arjan Hensen

TNO, Petten, Netherlands

Session 14. Leveraging Direct Flux Measurements Beyond Academia for Real-World Applications

In this work, the annual CO2 and N2O balance and analysis of the drivers for fertilized grassland on peat for a dairy farm under three groundwater level control options will be presented. 

This experiment is conducted in the context of the Dutch NOBV project (National Research program on GHG for peatland areas) as part of the Dutch Climate Agreement which has a chapter to reduce GHG emissions from peatland areas by 1 MtCO2-eq annually. 

The groundwater level control options applied are the conventional ditch water level control system, nowadays often being replaced by drainage and ditch level control, and finally drainage and pressure control. Several fields of the Zegveld experimental farm are divided in three segments each which a control option applied and a such allow study under comparable conditions.

The GHG fluxes reported are measured in parallel using one closed-path Aerodyne system switching inlet line each half hour using three small towers equipped with a Gill sonic anemometer at 1.75 m height in the middle of the largest elongated farm field. The location and low measurement height maximize the representation of the field in the flux measured from all wind directions. Flux loss tests and corrections, both using ogive analysis and comparison with an open-path COsystem installed at one location, as well as gap-filling methods are applied.


265 Strategy developed at the Regional Space Observatory to monitor carbon budget components on cropland in southwestern France

Poster

Rémy Fieuzal*, Ahmad Al Bitar, Veronica Antonenko, Ludovic Arnaud, Philippe Baillion, Aurore Brut, Nicole Claverie, Jean François Dejoux, Andrea Geraud, Herve Gibrin, Franck Granouillac, Ainhoa Ihasusta, Claire Marais Sicre, Tiphaine Tallec, Taeken Wijmer, Bartosz Zawilski, Eric Ceschia

Centre d’Études de la BIOsphère (CESBIO), Université de Toulouse, CNES/CNRS/INRAE/IRD/UT3, Toulouse, France

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

A coherent database is essential for the development, calibration, and validation of methods allowing to monitor the effect of carbon farming practices on SOC stock changes and carbon budget components (biomass, yield, CO2 fluxes). As a pilot site for the launch of Sentinel satellite missions, our predominantly agricultural study region in south-western France has regular long-term monitoring of carbon-related variables. The database combines in situ measurements (on two agricultural plots, flux towers and meteorological stations ensure since 2005 continuous acquisition of CO2, water and energy fluxes) and optical satellite images (acquisitions by Formosat-2, Spot-2/4/5, Landsat-5/8 and Sentinel-2), together with data and/or information on farming practices collected from various partners. This presentation provides an overview of the experimental carbon monitoring systems implemented as part of the RSO SO (Regional Space Observatory Sud-Ouest).

The transposition of the approaches developed on the study site on regions with contrasting conditions would increase the impact of the research work. The provision of comparable databases (via a device such as the Environmental Information System on our study site) on networks such as ICOS is an opportunity to study the transposability of the proposed models (Pique et al. 2000a, Pique et al. 2000b, Wijmer et al. 2023).


266 Contribution of soil organic carbon variations to the carbon footprint of a farm

Poster

Andrea Di Maria*, Bernard Heinesch

Gembloux Agro BioTech - University of Liege, Gembloux, Belgium

Session 13. In situ data for climate and other environmental services and policy support

Agricultural systems are confronted with the dual challenge of meeting the nutritional need of the population while mitigating their environmental impacts. Livestock production, responsible for 13% of global greenhouse gas (GHG) emissions, contributes to methane emissions from enteric fermentation and manure management, and nitrous oxide emissions from nitrogenous fertilizers application. 

Increasing soil organic carbon (SOC) content in farms ‘grasslands and croplands has been suggested as a strategy to mitigate the carbon footprint of livestock production. However, there is currently a lack of consensus on how to effectively include SOC variation into carbon footprint assessment methods, such as Life Cycle Assessment (LCA). 

This study conducts an LCA of a crop-livestock farm located in southern Wallonia, Belgium, to estimate the carbon footprint of the entire farm’s production in 2021. Furthermore, the study assesses the range of SOC variation in farm’s grasslands and croplands by combining data from successive regional SOC inventories and flux approach on two ICOS stations, located in the farm (for grasslands) or nearby (for croplands). 

The results reveal that the carbon footprint of the farm’s animal production in 2021 amounted to 10,2 kg of CO2-equivalent per kg of liveweight. Furthermore, SOC variation ranges from potentially augmenting this footprint by 2% to offsetting it by -22%, depending on the methodology used for SOC calculation.

This research highlights the complexities associated with integrating SOC variation into agricultural LCAs and emphasizes the need for further investigation in this area. 


267 New progress in the development of laser heterodyne radiometer for remote sensing of greenhouse gases from ground

Poster

Tingting Wei1, Marie-Therese Kattar1, Aditya Saxena Saxena1, Hervé Herbin2, Weidong Chen1*

1Université du Littoral Côte d'Opale, Dunkerque, France. 2Université de Lille, Lille, France

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

Measurement of vertical concentration profiles of atmospheric trace gases is of great interest to understand the physical-chemistry, dynamics, radiation budget of the atmosphere and to validate the results provided from chemical models and satellite observations. Compared to the currently used Fourier transform spectrometer for ground-based measurement of trace gases in the atmospheric column, the laser heterodyne radiometer (LHR) [1] offers unique advantages in terms of spectral resolution, sensitivity, spatial resolution, and instrumental dimension.

An all-fiber coupled LHR, using a wideband tunable external cavity diode laser (1500–1640 nm) as local oscillator, was developed for remote sensing of CO2 from ground. A field campaign was performed in Dunkerque [2]. The measured LHR spectra in the atmospheric column are compared, in good agreement, with referenced Fourier-transform infrared spectra from the TCCON observation network and with the simulation spectra resulting from an atmospheric transmission modeling. Experimental details will be discussed and presented.

Acknowledgments

This work was supported by the projects of LABEX CaPPA (ANR-10-LABX005), CPER ECRIN and EU H2020-ATMOS (Marie Skłodowska-Curie grant No 872081).

References

[1]  D. Weidmann, "Atmospheric trace gas measurements using laser heterodyne spectroscopy", Ch. 4, pp. 159-223, in Advances in Spectroscopic Monitoring of the Atmosphere, eds. by Weidong Chen, Dean S. Venables, Markus W. Sigrist, ISBN: 978-0-12-815014-6, Elsevier (2021)

[2] J. Wang, T. Tu, F. Zhang, F. Shen, J. Xu, Z. Cao, X. Gao, S. Plus, and W. Chen, "An external-cavity diode laser-based near-infrared broadband laser heterodyne radiometer for remote sensing of atmospheric CO2", Optics Express 31 (2023) 9251-9263


268 High uncertainty in ocean afforestation efficiency due to stoichiometric variability and iron limitation

Poster

Manon Berger1*, Lester Kwiatkowski2, David Ho3, Laurent Bopp1

1LMD/ENS/IPSL, Paris, France. 2LOCEAN/IPSL, Sorbonne Université, CNRS, IRD/MNHN, Paris, France. 3University of Hawaiʻi at Mānoa, Honolulu, USA

Session 8. Enhancing the ocean carbon sink: the science, verification, and governance of marine-based carbon dioxide removal (mCDR)

Carbon dioxide removal (CDR) has emerged as a crucial component of climate change mitigation strategies. Among the various CDR approaches, ocean afforestation via macroalgae cultivation shows promise due to its high productivity and carbon-to-nutrient ratio. Macroalgae cultivation shifts production from phytoplankton to macroalgae. The CDR efficiency is closely related to the comparative ability of macroalgae and phytoplankton to fix carbon with a given nutrient pool according to their stoichiometry. The carbon-to-nitrogen (C:N) and carbon-to-phosphorus (C:P) ratios in seaweed tissue exhibit significant variability, influenced by environmental factors. However, current modeling efforts have overlooked the variability of stoichiometry, as well as the critical role of iron limitation and consumption by macroalgae. 

Using the NEMO-PISCES ocean biogeochemical model, we explore the spectrum of stoichiometric variability observed in macroalgae, along with a range of half-saturation constants. Under a prescribed macroalgal production rate of 0.5 PgC yr−1, stoichiometry is found to be the primary driver of CDR efficiency, with efficiencies ranging from -50% to 91%. Notably, the largest uncertainty is introduced by C:P ratio variability. 

       In terms of global production potential, both stoichiometry and half-saturation constants are equally important, with iron being the most critical element. Furthermore, the iron consumption and limitation reduce macroalgal production potential by up to eightfold and CDR efficiency by 17% globally. This result underscores the need to consider this dependency in discussions surrounding afforestation strategies. 


269 From forest to atmosphere: towards a more comprehensive assessment of BVOC exchanges in a mixed temperate forest

Oral

Clément Dumont1*, Bert Verreyken1,2, Niels Schoon2, Crist Amelynck2,3, Bernard Heinesch1

1Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium. 2Belgian Institute for Space Aeronomy, Brussels, Belgium. 3Department of Chemistry, Ghent University, Ghent, Belgium

Session 2. Exchange of reactive gases and aerosols between the land surface and the atmosphere in natural and managed ecosystems

Forests are the primary global source of biogenic volatile organic compounds (BVOCs), pivotal in atmospheric chemistry. While emissions of isoprene and monoterpenes, the most emitted BVOCs at the global scale, are generally well-estimated, uncertainties persist regarding the diversity, magnitude, and temporal variability of other BVOC exchanges that impact the non-methane volatile organic compound (NMVOC) budget and atmospheric chemistry.

To address this, half-hourly net BVOC fluxes were measured at the Vielsalm ICOS station, a Belgian mixed temperate forest, during spring-autumn 2023, using a PTR-TOF-MS instrument (PTR-TOF-4000, Ionicon Analytik GmbH) and eddy covariance. In total, 33 VOC-related m/z values showed significant emissions or depositions.

Throughout the campaign, the net BVOC exchanges are positive, with the top 10 BVOCs accounting for 90% of observed BVOC emissions (in mass balance), led by monoterpenes, isoprene, and methanol. Isoprenoids and their derivates were emitted consistently, influenced by air temperature and solar radiation. Conversely, lighter oxygenated BVOCs like alcohols, organic acids, and aldehydes exhibited bidirectional net fluxes, sometimes favouring deposition, especially in lower photochemical and higher humidity conditions.

To investigate their impact on atmospheric reactivity, fluxes were multiplied by their corresponding reaction rate constants with OH radicals. Isoprene and monoterpenes were found to account for 70% and 22% of the total OH reactivity flux, respectively.

Further analysis will focus on bi-directional exchanges of VOCs between the forest canopy and the atmosphere. For this, we will start by comparing our results with existing emission models (e.g., MEGAN) and focus on deposition occurring in the canopy.


270 Quantification of carbon dioxide and methane emissions from a Chinese city based on eddy covariance measurements

Poster

Kai Wang1*, Yuting Zhang1, Yimeng Li1, Ting-Jung Lin2, Yin Wang3, Kai Wu1, Xunhua Zheng1

1Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China. 2Ningbo Institute of Digital Twin, Eastern Institute of Technology, Ningbo, China. 3HealthyPhoton Technology Co., Ltd, Ningbo, China

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Accurate quantification of greenhouse gas (GHG) emissions from cities is essential to support the local climate change mitigation actions. Eddy covariance (EC) technique provides the most direct and reliable data for estimating GHG emissions at local scale. So far, most GHG EC studies in urban area were reported in Europe and the United States. However, only a very limited number of reports are from China. Here, we present EC flux measurements of CO2 and CH4 in the urban area of Ningbo, a city in the eastern China with a population of near 4 million in its central urban area. Since the December of 2022, CO2 and CH4 fluxes have been simultaneously measured at 100 m height on a 140 m tall TV/radio transmitter tower in the city center. This is the first long-term EC flux dataset of both CO2 and CH4 from a Chinese city. The results show that the city was a net source of CO2 and CH4 during all seasons. The CO2 flux of Ningbo was lower than most European cities and the CH4 flux was lower than London and Florence. Significant increase in both CO2 and CH4 emissions were observed after the lift of COVID lockdown. In this presentation, we will discuss the temporal and spatial patterns of CO2 and CH4 fluxes, as well as comparison with inventory estimates. Such long-term EC measurements in Chinses cities are significant in the context of national policy of “coal-to-gas” and the increasing popularity of electric vehicles in China.


271 SCOUT: Street-Level Carbon Observatory for Urban Terrain

Oral

Daniel Kühbacher1*, Jia Chen1, Julian Baertschi1, Ali Ahmad Khan1, Adrian Wenzel1, Patrick Aigner1, Stuart Grange2, Pascal Rubli2, Lukas Emmenegger2

1Technical University of Munich (TUM), Munich, Germany. 2Swiss Federal Laboratories for Materials Science and Technology (Empa), Duebendorf, Switzerland

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

City governments worldwide are implementing climate protection strategies to reduce carbon emissions and adapt to the ever-increasing challenges of climate change. Measurement, Reporting, and Verification (MRV) capabilities are vital in guiding these efforts, aiding in developing targeted strategies, tracking their progress, and assessing the outcome. Utilizing urban atmospheric CO2 measurements to inform climate action plans provides vital information on direct carbon emissions and their spatial and temporal variability.

We introduce a street-level CO2 sensor network comprising 100 commercially available, battery-powered, low-cost nodes installed on lamp posts across Munich. The sensors are strategically positioned at locations with different emission characteristics and partly co-located with air quality sensors, traffic detectors, and more precise CO2 sensors to assess data correlations and quality. 

An accuracy improvement of factor 3 to 10 compared to the manufacturer’s accuracy (50 ppm) was achieved with our bias correction algorithm and individually trained sensor models. Each device includes additional temperature, humidity, and atmospheric pressure sensors that were used as predictors for machine learning algorithms. Additionally, we upgraded the systems with solar radiation shields to mitigate radiative heating effects and reduce temperature-induced sensor errors. Our sensor characterization process includes over four months of reference measurements using a PICARRO G2301 analyzer across three seasons. Furthermore, we performed climate chamber experiments following defined temperature, humidity, and CO2 concentration protocols. 

We will share insights from network operations, introduce our newly developed, automated data processing pipeline, and discuss initial findings and learnings gleaned from the sensor data.


272 Constraining a data-driven bottom-up CO2 flux model by ecosystem and atmospheric observations using atmospheric transport

Oral

Samuel Upton1*, Markus Reichstein1, Wouter Peters2,3, Santiago Botia4, Jacob Nelson1, Sophia Walther1, Fabian Gans1, Saqr Munassar4, Ana Bastos1

1Department of Biogeochemical Integration, Max Plank Institute of Biogeochemistry, Jena, Germany. 2Environmental Sciences Group, Wageningen University, Wageningen, Netherlands. 3University of Groningen, Centre for Isotope Research, Gronigen, Netherlands. 4Department of Biogeochemical Signals, Max Plank Institute of Biogeochemistry, Jena, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Globally, atmospheric stations measure CO2 concentration influenced by large-scale signals, while eddy-covariance towers measure the net flux of CO2 between the biosphere and the atmosphere (NEE) at the ecosystem level. Models used to derive the net flux of CO2 from these top-down and bottom-up data sources produce very different estimates of the global land CO2 sink and its spatio-temporal variability. This mismatch contributes to the overall uncertainty in the land sink.

This study aims to reduce this uncertainty by creating a bottom-up flux model and adding a constraint from atmospheric observations of CO2 concentration, combining the strengths of both approaches. To achieve this, we use the Stochastic Time Inverse Lagrangian Transport model to transform the fluxes inferred by the bottom-up data-driven model into concentrations, allowing for optimization using the observational data. This atmospheric term in the objective function allows the model to run for a large area not covered by eddy-covariance measurements, increasing the exposure of the bottom-up model to a range of biomes as the winds shift throughout the year, providing the system with a more complete view of the underlying distribution of the variables driving NEE.

This study demonstrates the beneficial impact of adding an atmospheric constraint to a bottom-up flux model. When compared with a bottom-up model, our model produces an interannual variability that is closer to estimates from top-down systems. And, unlike top-down approaches, our model creates an estimate of NEE which is linked to ecosystem-level data and directly comparable to the eddy-covariance record.
 

273 Demonstrating atmospheric O2/N2 measurements as a proxy for fossil fuel CO2 in the city of Heidelberg, Germany

Oral

Penelope Pickers1,2*, Susanne Preunkert3,4, Fabian Maier5,3, Ingeborg Levin3, Andrew Manning1, Maksym Gachkivskyi3,4, Christian Rödenbeck5, Julian Della Coletta3,4, Xochilt Gutiérrez6, Samuel Hammer3,4

1Centre for Ocean and Atmospheric Sciences, University of East Anglia, Norwich, United Kingdom. 2National Centre for Atmospheric Science, University of East Anglia, Norwich, United Kingdom. 3Institut für Umweltphysik, Heidelberg University, Heidelberg, Germany. 4ICOS Central Radiocarbon Laboratory, Heidelberg University, Heidelberg, Germany. 5Max Planck Institute for Biogeochemistry, Jena, Germany. 6ICOS Flask and Calibration Laboratory, Max Planck Institute for Biogeochemistry, Jena, Germany

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

The ability to isolate the fossil fuel CO2 (ffCO2) component of total atmospheric CO2 is a crucial part of top-down atmospheric ffCO2 verification efforts, owing to large non-fossil fluxes of CO2 in and out of the terrestrial biosphere. Atmospheric measurements of radiocarbon (14CO2) are the gold standard for this purpose, but the availability of such data is currently limited due to its high cost. Furthermore, continuous radiocarbon measurement capability, while promising, is not yet available with sufficient precision. 

            Here, we present an alternative observational approach for separating ffCO2 and non-fossil CO2 using continuous atmospheric measurements of O2/N2 and CO2 from the city of Heidelberg in Germany. The continuous O2/N2 and CO2 data are combined into the quantity “Atmospheric Potential Oxygen” (APO), a tracer that (by design) is invariant to CO2 and O2 fluxes from/to the terrestrial biosphere. We demonstrate that APO can be used as a continuously measurable proxy for ffCO2 in Heidelberg by comparing to 14CO2-based estimates of ffCO2 from over 500 flask samples, which were collected over a period of two and a half years from 2018-2021. We examine the variability in APO:ffCO2 ratios and quantify APO-based ffCO2 uncertainties during different seasons.


274 SOOP - Shaping an Ocean of Possibilities: Improving Ocean Observations through Science-Industry Collaboration

Poster

Tobias Steinhoff1*, Toste Tanhua1, Sören Krägefsky2, Klas Ove Möller3

1GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany. 2Alfred Wegener Institute Helmholtz-Center for Polar andMarine Research, Bremerhaven, Germany. 3Helmholtz Zentrum Hereon, Geesthacht, Germany

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

Vast parts of the ocean are not monitored at all and are widely unknown, and there is a significant need for more fit-for-purpose in-situ observations. At present, ocean observation systems are a bespoke market where standardisation and economies of scale are not always achievable. Here, we present the recently funded innovation platform of the German Helmholtz Association “Shaping an Ocean of Possibilities for science-industry collaboration (SOOP)”. We are going to harness the curiosity and creativity of our partners to sample essential ocean and climate variables including ocean carbon at unprecedented scales. SOOP aims to bring users, developers and manufacturers of sensors together around a set of key innovative projects. SOOP thus provides a platform of cooperation between industry, science and civil society to jointly build competencies and growth of ocean observations and technology. SOOP supports the growth of the “New Blue Economy” sector by actively enhancing the bi-directional knowledge and technology transfer between science and industry. 

We will present ongoing projects concentrating on marine carbon observations and a variety of platforms. The SOOP platform will grow (in terms of partners and EOVs) based on the experiences from diverse pilot projects. These projects are aimed at developing ocean observation equipment based on common protocols that can be fitted to a whole range of platforms, ranging from recreational vessels to global container fleets. SOOP aims to activate non-scientists to scale-up science-grade ocean observations for a more sustainable use of our oceans.


275 Locating the signal: mapping the carbon landscape of European cities to inform urban emission monitoring strategies

Poster

Ida Storm1,2,3*, Ute Karstens1,3, Alex Vermeulen3,1, Wouter Peters2, Theo Glauch4,5, Ingrid Super6

1ICOS Carbon Portal, Lund University, Physical Geography and Ecosystem Sciences, Lund, Sweden. 2Wageningen University, Environmental Sciences Group, Wageningen, Netherlands. 3ICOS ERIC, Carbon Portal, Lund, Sweden. 4University of Heidelberg, Institute of Environmental Physics, Heidelberg, Germany. 5German Aerospace Center (DLR), Institute for Atmospheric Physics, Weßling, Germany. 6Netherlands Organization for Applied Scientific Research, Utrecht, Netherlands

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Imagine a city in Europe. Does it have lots of parks and vegetation, or are its streets busy and filled with cars? Do you see plumes coming from chimneys of heavy industry or a coal-fired power plant? In this study, we collect such characteristics to improve our understanding of the so-called “carbon landscape” of 308 European cities. Understanding this landscape can guide decisions on emission mitigation and monitoring. Common traits across clusters of cities help identify the most effective monitoring strategies for each cluster. Our study collects, selects, clusters, and interprets these 308 carbon landscapes, and the resulting data and maps are made publicly available at the ICOS Carbon Portal.
 We will demonstrate the power of our clustering approach by showing how city-wide emissions compare to the net biogenic drawdown and how this helps us define a monitoring measurement strategy. In many of the cities, during summer daytime hours, the biogenic CO2 uptake exceeds fossil fuel emissions by a factor of 10. This indicates that measurements should be focused during winter when the emission signal is stronger. However, during winter daytime hours, the biosphere generally becomes a net source of carbon, contributing a significant (>30%) share to the carbon budget in half of the cities. Thus, these cities would benefit from a monitoring strategy that helps separate the biospheric component from fossil fuel emissions, using methods such as co-emitted species detection or radiocarbon analysis.


276 Gas exchange patterns of CAM plant Agave sisalana and photosynthetic plasticity as environmental response measured by eddy covariance

Poster

Angelika Kübert1*, Mikko Skogberg1, Kukka-Maria Kohonen2, Annalea Lohila1,3, Lutz Merbold4,5, Ilja Vuorinne1, Petri Pellikka1,6, Timo Vesala1

1University of Helsinki, Helsinki, Finland. 2ETH Zürich, Zürich, Switzerland. 3Finnish Meteorological Institute, Helsinki, Finland. 4Agroscope, Zürich, Switzerland. 5International Livestock Research Institute, Nairobi, Kenya. 6University of Nairobi, Kangemi, Kenya

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

The Crassulacean acid metabolism (CAM) is a special adaptation to dry conditions that enables plants to take up carbon during night. Only few studies assessed the gas exchange of CAM plants at the ecosystem level. Here, we measured the net CO2 exchange of the CAM plant Agave sisalana using the eddy-covariance method in an agricultural field in semi-arid Kenya. Our measurements spanned 65 days and started in a wet period that gradually turned into a dry period. We observed high productivity of A. sisalana during the wet period which was linked to significant day- and nighttime carbon uptake, suggesting direct CO2 fixation via the C3 pathway during daytime. In the dry period, daytime net CO2 exchange switched from carbon uptake to carbon release, suggesting a shift towards strict CAM photosynthesis in response to drier soils. Our results show the high photosynthetic plasticity of Agave sisalana in response to soil drying and its importance for the net CO2 exchange at the ecosystem level. 


277 Feedback between climate, land-atmosphere fluxes and structure in a forest ecosystem severely damaged by recent hot-droughts

Oral

Andreas Christen1*, Simon Haberstroh2, Florian Imbery3, Hans-Peter Kahle4, Jürgen Kreuzwieser2, Thomas Plapp1, Dirk Schindler1, Fabio Scarpa2, Thomas Seifert4, Markus Sulzer1, Christiane Werner2

1University of Freiburg, Environmental Meteorology, Freiburg, Germany. 2University of Freiburg, Ecosystem Physiology, Freiburg, Germany. 3German Meteorological Service, Offenbach, Germany. 4University of Freiburg, Forest Growth and Dendroecology, Freiburg, Germany

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Re-occurring dry and hot summers with high irradiance have caused irreversible damages in forest ecosystems across Central Europe, including the ICOS ecosystem associate site Hartheim (DE-Har). The site experienced irreversible damages to a Scots pine (Pinus sylvestris) plantation with a mortality of >50% of all P. sylvestris trees following the 2018 drought. Dead and fallen trees were generally not removed in the area surrounding the site. In the last 6 years, DE-Har has undergone a significant regime change in which increased light under the damaged/missing tree crowns has accelerated growth of deciduous understory trees. We use eddy covariance measurements from pre- and post-drought periods and combine them with ecophysiological measurements at the individual tree level to estimate effects on long-term carbon, energy and water fluxes. We find that CO2 uptake in summer is only about 40% of pre-drought uptake and that in the period 2019-2023 the site became an annual net carbon source, whereas 15 years ago the forest was a considerable COsink. Ecophysiological measurements show that understory trees have higher transpiration and ecophysiological activity compared to the previously dominant P. sylvestris canopy. On a decadal scale, annual transpiration decreased, most notably in winter, and the seasonality of fluxes was intensified, as can be seen on remote sensing products related to canopy greenness such as satellite-based vegetation indices and phenocams. The observed changes altogether provide information on how forests that reached tipping points transition functionally and structurally and how this affects interactions between land and atmosphere.


278 Application of in situ CO2 and CH4 concentrations measurements on-board UAV to monitor surface emissions on a grazed grassland, against ground-based Eddy Covariance

Poster

Jean-Louis Bonne1*, Delphine Combaz1, Sami Omrane1, Nicolas Dumelié1, Jérémie Burgalat1, Florian Parent1, Christophe Flechard2, Pauline Buysse2, Yannick Fauvel2, Lilian Joly1

1GSMA UMR 7331, Université de Reims Champagne-Ardenne, CNRS, Reims, France. 2INRAE, UMR SAS 1069, Institut Agro, Rennes, France

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

An open-path laser absorption spectrometer has been developed to measure in situ CO2 and CH4 concentrations on-board Uncrewed  Aircraft Vehicles (UAV). Associated with a mass balance model, it proved suitable to detect and quantify point-source emissions with fluxes down to 0.01 g/s in industrial contexts (Bonne et al., AMTD, 2023). New developments were conducted on the instrument, including a newly embarked 2D ultrasonic anemometer, together with sensitivity and stability improvements. 

To explore potential new applications of this instrument to diffuse surface emissions with low concentrations enhancements and benchmark it against an already established Eddy-Covariance flux tower, a monitoring campaign has been conducted in 2024 on the grazed grassland at the FR-Mej (Méjusseaume) flux tower site. 

The site is an ICOS-Ecosystems associated station over intensively managed grazed grassland, part of the INRAE-IEPL dairy experimental farm (180 dairy cows and 170 dairy goats) situated in NW France. The field is grazed by dairy cattle 4 to 6 times yearly, with a livestock density between 20 and 60 LSU/ha during grazing phases. Methane surface fluxes are monitored using the eddy covariance technique, with wind and turbulence measured by a Gill HS50 3-D ultrasonic anemometer and CH4 mixing ratios measured at 10 Hz by a MIRO MGA quantum cascade laser analyser. Half-hourly fluxes were derived using the Eddypro software. 

This experiment is part of an effort to apply these UAV-based measurement to various types of natural or anthropogenic sources including bogland or agricultural biogas digesters.


279 A new open‐path CH4/H2O analyzer for eddy covariance CH4 flux measurements with minimal temperature-related spectroscopic corrections

Poster

Wenru Yang1*, Huancheng Zhang1, Kai Wang2, Ting-Jung Lin3, Xunhua Zheng2, Yin Wang1

1HealthyPhoton Technology Co., Ltd, Ningbo, 315100, China. 2State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP-CAS), Beijing, 100029, China. 3Ningbo Institute of Digital Twin, Eastern Institute of Technology, Ningbo, 315100, China

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

Eddy covariance (EC) flux measurement based on open-path laser spectroscopic gas analyzers is widely used for CH4 flux measurements, but current commercial analyzers are subject to significant spectroscopic corrections for the in-situ temperature fluctuations, leading to large uncertainties in the measured background CH4 fluxes. The modified Webb‐Pearman‐Leuning (WPL) approach was introduced to help reduce errors in open‐path or temperature/pressure‐uncontrolled flux measurements due to spectroscopic effects.

This work presents an open-path CH4/H2O dual-component laser analyzer (Model: HT8600-Plus, HealthyPhoton Co., Ltd.) suitable for future EC CH4 flux measurements with minimal temperature-related flux corrections. HT8600-Plus utilizes an interband cascade laser (ICL) to simultaneously probe the mid-infrared transitions of CH4 at ~3221 nm and H2O at ~3223 nm. The CH4 absorption line was selected by considering spectroscopic effects that counteract density changes resulting from temperature fluctuations, thereby nearly mitigating the combined impact of density and spectroscopic effects. 

Field experiments are performed to compare fluxes measured from a single HT8600-Plus instrument against fluxes measured from a two-unit system with a commercial open-path CH4 analyzer and an NDIR CO2/H2O analyzer. Preliminary results showed that raw fluxes from HT8600-Plus achieved high consistency with the modified-WPL corrected fluxes from the commercial analyzers, indicating its versatility for field CH4 flux monitoring and the low temperature-related flux corrections as proposed.


280 Investigating high-latitude carbon cycle response using an EC-Earth framework

Poster

Rayanne Vitali1*, Peter Langen1, Anna Rutgersson2, Erik Jan Schaffernicht2, Lichuan Wu2, Minchao Wu2,3

1Aarhus University, Roskilde, Denmark. 2Uppsala University, Uppsala, Sweden. 3Lund University, Lund, Sweden

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

High latitude and Arctic regions are critical in understanding climate change dynamics: harbouring critical tipping points, storing vast carbon stocks, and experiencing accelerated warming rates surpassing those of any other region on the planet. However, the complexities of Arctic processes pose significant challenges for accurate prediction. Projections of changes in the Arctic regions have low confidence, primarily due to uncertainties associated with modeling multiple interacting drivers and ecosystem responses. Thus, enhancing our understanding of high latitude processes, their interactions, and associated feedbacks is crucial for comprehending the global response to future climate change.

Work presented here forms part of the GreenFeedBack project and aims to assess the strengths of high latitude terrestrial, freshwater and ocean processes, interactions, and their associated feedback using an Earth System Modelling framework. Using results from fieldwork and modelling studies, we implement changes to high latitudes into the EC-Earth model before conducting a series of sensitivity simulations spanning historic, present, and future scenarios. Simulations are then complimented by a budgeting framework, facilitating the assessment of greenhouse gas fluxes, and allowing an assessment of the different high latitude processes through a flux box model. 

While still in its early stages, this study demonstrates the potential of our framework methodology. Preliminary results showcase how our approach can illuminate key processes governing Arctic carbon cycle response and feedback under climate warming. By refining our understanding of high latitude dynamics, we aim to contribute to more accurate climate change predictions and mitigation strategies.


281 A new ICOS Class 1 station at CNR-IMAA: starting a new infrastructure in the hearth of Mediterranean basin.

Poster

Emilio Lapenna*, Francesco Cardellicchio, Teresa Laurita, Isabella Zaccardo, Serena Trippetta, Davide Amodio, Aldo Giunta, Antonella Buono, Alessandro Mauceri, Lucia Mona

CNR-IMAA, Potenza, Italy

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

At the Istituto di Metodologie per l’Analisi Ambientale of the Italian National Research Council (CNR-IMAA) we have completed the construction of the new ICOS-compliant Class 1 POT station tower and the implementation of the laboratory systems. In order to perform preliminary test of the entire system with the a first characterization of the site from the point of view of greenhouse gases, we plan to start the measurmentes within the next 4 months.

Our station will provide important measures within the ICOS network since in the Mediterranean basin there is only one Class 1 station. We recall that our site is located in Tito (Southern Italy, 40.60° N, 15.72° E, 760 m asl), close to Potenza City (~ 7km), in a plain surrounded by low mountains (below 1100 m asl), less than 150 km from the West, South and East coasts. It is characterized by a typical mountain weather strongly influenced by Mediterranean atmospheric circulation, resulting in generally dry, hot summers and cold winters.

The station is located close to the CNR-IMAA main premises which hosts an operative ACTRIS site providing atmospheric measurements since 2000, giving us the opportunity to study and characterize atmospheric circulation with an overarching approach, by performing synergistic investigation of GHGs and atmospheric aerosol, also considering the hints that can be derived by continuous measurements of isotopic mixture of carbon dioxide 14COin order to disentangle the anthropogenic pollution sources and their evolution with time.


283 Assessing LAKE 2.0 model performance in simulating thermal and greenhouse gases dynamics in a small boreal lake in southern Finland

Poster

Marta Fregona*, Joonatan Ala-Könni, Ivan Mammarella

Institute for Atmospheric and Earth System Research (INAR) / Physics, University of Helsinki, Helsinki, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Lakes are significant sources of carbon dioxide and methane to the atmosphere. In addition, the lake mixing regimes and carbon budget are changing rapidly in response to the influence of climate change. Being able to accurately simulate thermal and gas related dynamics thus turns out to be a relevant task because it enables the prediction of future shifts in temperature patterns and gas exchange rates between lakes and the atmosphere. Despite this, however, most field and modeling studies have focused on the open-water season or summer with limited consideration of seasonal and interannual variability.

Here, we use the one-dimensional model LAKE 2.0 to simulate profiles of temperature and dissolved gas concentration in Lake Kuivajärvi (southern Finland). Model’s performances are assessed by using high frequency and multiple years field measurements with special attention to shoulder seasons (spring and fall). 

Seasonal dynamics of water temperature and gases are effectively reproduced by the model (Root Mean Square Error for water temperature 1.8-2.4 °C over the entire column). Focusing on shoulder seasons, there are some shifts in gas accumulation amount and timing which are highly dependent on the model's ability to accurately simulate temperature dynamics. These biases are particularly evident in early warm winters when the presence of thin and intermittent ice cover prevents gas accumulation. As these conditions will likely occur more often in a warmer climate, models should be able to accurately simulate these dynamics as well.


284 Evaluation of Source and Sink Contributions to Urban Flux Tower Measurements Using Flux Footprint Modelling

Oral

Betty Molinier1*, Natascha Kljun1, Patrick Aigner2, Dominik Brunner3, Jia Chen2, Andreas Christen4, Lionel Constantin3, Hugo Denier van der Gon5, Rainer Hilland4, Daniel Kühbacher2, Stavros Stagakis6, Ingrid Super5

1Lund University, Lund, Sweden. 2Technical University of Munich, Munich, Germany. 3Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland. 4University of Freiburg, Freiburg, Germany. 5Netherlands Organisation for Applied Scientific Research, The Hague, Netherlands. 6University of Basel, Basel, Switzerland

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Greenhouse gas (GHG) emissions from cities are important due to the broad mixture of their sources, their magnitude, and the large percentage of humans working or residing in these environments. Therefore, targeted reduction of urban GHG emissions is highly relevant for climate change mitigation plans. As part of the ICOS Cities/PAUL project, GHG flux measurements using the eddy-covariance technique have been established in three pilot cities (Zurich, Paris, Munich) to understand how city size/structure and sink/source mixture affect GHG emissions. However, flux measurements alone cannot answer all questions concerning emission sources and paths for reduction. The relative importance of different sectors contributing to measured fluxes needs to be determined, e.g., by using a flux footprint model to describe the spatial extent and temporal variation of the sources contributing to the measured fluxes. 

We present footprints and land cover type contributions for the flux towers of the three ICOS pilot cities using the Flux Footprint Prediction (FFP) model (Kljun et al. 2015) to bridge the gap between emissions and source attribution. We show how the relative contributions of sources and sinks vary temporally by city. We also combine our footprint calculations with CO2 flux estimates and highly spatially- and temporally-resolved emission inventories in all three pilot cities. The presented first results are a valuable step forward in evaluating emission inventories and attributing emissions to various sectors. This enables us to identify disparities in our understanding of urban emissions and which sectors to target in local climate action plans.


285 Map-IO: atmospheric and oceanic observation program in the Southern Indian Ocean

Oral

Michel Ramonet1*, Marc Delmotte1, Morgan Lopez1, Christian Roedenbeck2, Frédéric Chevallier1, Lynn Hazan1, Laura Burlot1, Hippolyte Leuridan1, Massaer Kouyaté1, Pierre Tulet3

1Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France. 2Max Planck Institute for Biogeochemistry, Jena, Germany. 3LAERO, Laboratoire d’Aérologie, UMR 5560 CNRS, UT3, IRD, Toulouse, France

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Due to its remoteness, the Southern Ocean is one of the least studied areas in the world. The MAP-IO program (Marion Dusfresne Atmospheric Program - Indian Ocean) aims to compensate for the lack of observation in this region of the globe by equipping the Marion Dufresne ship with a set of in-situ and remote sensing instruments for the study of the atmosphere and ocean. MAP-IO does not organize specific campaigns, but operates several analyzers on all the ship's routes, most of which take place in the Southern Indian Ocean. As part of this full instrumental package, a complete greenhouse gases (GhG) equipment has been installed in November 2020, including a continuous high precision analyzer (providing CO2, CH4, CO measurements), a calibration and quality control setup and intake line and a GPS positioning system. El Yazidi et al. (2018) method to detect spikes is applied to filter the major contaminations from the ship's chimney, based on the CO variability. 

In this presentation, we will review the measurements obtained, their integration into the surface measurement network, and their comparison with different atmospheric model simulations (CAMS reanalysis, LMDz, TM3). Depending on the ship's positioning and the season, the gradients observed are more or less affected by air/sea CO2 fluxes, and by exports from southern African continent. A study of the various campaigns carried out since 2020 enables us to assess the contribution of this new observation program to a better understanding of CO2 gradients in this part of the world.


286 Long-term trend of anthropogenic emissions measured with eddy covariance in Firenze

Oral

Tommaso Giordano1,2*, Simone Putzolu1, Lorenzo Brilli1, Valentina Marchi1, Alessandro Zaldei1, Carolina Vagnoli1, Giovanni Gualtieri1, Beniamino Gioli1

1Consiglio Nazionale delle Ricerche - Istituto per la BioEconomia, Florence, Italy. 2University of Florence - Department of Civil and Environmental Engineering, Florence, Italy

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

The IT-OXm ICOS Associated site is located in the central area of Firenze, Italy, measuring fluxes on a footprint area made by >90% of anthropogenic land uses. The site has been operational since 2005 despite some data gaps, offering the opportunity to assess long-term trends of surface emissions. Fluxes were aggregated and gap-filled at a weekly scale and then subject to trend analysis using the Mann-Kendall test before and after the COVID outbreak. Yearly fluxes spanned from 17.5 (2015) to 35.2 (2023) kgCO2 m-2 y-1. A significant emission reduction of 1.42 kgCO2 m-2 y-1 was observed from 2006 to 2015, followed by a period (2016-2019) with an uncertain trend due to a data gap, while a significant increase of 4.30 kgCO2 m-2 y-1 was observed from 2020 to 2023. While the 2020 emissions are among the lowest due to the COVID restrictions effect, the 2023 emissions are the highest measured. Analyzing touristic flow data, a positive significant correlation between amounts of non-resident citizens and CO2 emissions in the last 3 years was observed. However, the sole official tourism inventorial data do not completely explain the observed emission increase, suggesting that emission sources are not entirely mapped by inventorial data. These data highlight that decarbonization policies to reach carbon neutrality (Firenze is among the 100 EU climate-neutral cities by 2030) under scenarios of an increasing number of citizens, both residential and touristic, remain challenging and call for structural investments in the decarbonization of buildings, services, and mobility.


287 Effects of management and temperature anomalies on grassland CO2 fluxes using a long-term eddy covariance dataset

Poster

Bruna Winck1,2, Juliette Bloor2, David Colosse2, Olivier Darsonville2, Luc Michaud2, Katja Klumpp2*

1INRAE-ECOSYS, Palaiseau, France. 2INRAE-UREP, Clermont-Ferrand, France

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Air temperature (Tair) anomalies and their extremes such heatwave cold spells have the potential to modify ecosystem functioning and delivered services. To date, few studies have investigated the combined effect of Tair anomalies and agricultural management on CO2 flux components using long-term data. Here, we analyzed long-term carbon fluxes and Tair data (2003-2021) for interactions between Tair anomalies and flux anomalies, for two upland grassland management treatments (low and high cattle grazing). The grassland site experienced on average a month of anomalous temperature (colder/warmer) and ~10 days of extreme events per year. CO2 fluxes were most affected by Tair anomalies at the start of the growing season, period during which the strongest increases of gross primary productivity (GPP) and ecosystem respiration (Reco) were observed. However, these effects were season and treatment-dependents.  GPP and Reco tend to increase in warmer days except in summer and autumn, where CO2 fluxes have been down-regulated under extreme warm conditions (> 6 days of anomalous Tair). CO2 fluxes were reduced likely due to the exceedance of Tair stress threshold, which here was identified at 20°C. Analyses suggest a greater sensitivity to Tair anomalies for high versus low grazing management, highlighting the importance of management x climate interactions. Our findings evidenced the use of long-term data at fine-scale improves our understanding on the importance of timing and the nature of Tair anomalies on CO2 fluxes.


288 Tools for Easy Analysis of ICOS data

Oral

Ida Storm1,2*, Ute Karstens1,2, Claudio D'onofrio1,2, Alex Vermeulen2,1, Klara Broman1,2, Jonathan Schenk1,2, Oleg Mirzov1,2, Zois Zogopoulos1,2, André Bjärby1,2

1ICOS Carbon Portal, Lund University, Physical Geography and Ecosystem Sciences, Lund, Sweden. 2ICOS ERIC, Carbon Portal, Lund, Sweden

Session 16. Continuous Learning in a changing world - Teaching and learning novel tools & methods used for measurement techniques’, data & policy

If you are looking for data on greenhouse gases, the ICOS data portal is an excellent starting point. A faceted search helps you to navigate an extensive data repository, with datasets from the ecosystem, ocean, and atmosphere. Many datasets can be previewed directly on the portal through interactive graphs. For further analysis, it is possible to download the data directly from the portal. However, there is another way. Join this session to let us show you! No need to download the data to your computer – instead, bring the computation to the data. Together, we will explore how to navigate from the ICOS data portal to our ICOS Jupyter service, a free virtual research environment (VRE) provided by ICOS. Here, the ICOS Python libraris will be showcased, and you can either just watch or choose to follow along on your own computer. For the latter all you need is an internet connection and a web browser. The VRE enables instant analysis and the creation of various types of graphs, without having to install fancy software on your local computer. The process is designed to be smooth and user-friendly, suitable for both beginners and experts.


289 Influence of deep stratosphere-to-troposphere transport to atmospheric carbon dioxide and methane at the Mt. Cimone WMO/GAW Global Station (2165 m a.s.l., Italy) over 2015 - 2022

Poster

Pamela Trisolino1, Davide Putero2, Paolo Cristofanelli1*, Jgor Arduini3, Michela Maione3, Francesca Marcucci4, Stefano Amendola4

1CNR - ISAC, Bologna, Italy. 2CNR - ISAC, Torino, Italy. 3Università di Urbino Carlo Bo, Urbino, Italy. 4Aeronautica Militare, CAMM, Sestola, Italy

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

This work was dedicated to provide a first systematic assessment of the role played by deep stratosphere-to-troposphere transport events (denoted as “stratospheric intrusions (SIs)”) in influencing the CO2 and CH4 variability at a high mountain site in Italy (Monte Cimone, CMN, 2165 m a.s.l.). To select SI events, we used a methodology based on the analysis of the temporal variability of in-situ observed stratospheric tracers (O3, CO and RH), modeled PV along 5-day back-trajectories starting at the measurement site, and satellite measurements of total column ozone (TCO). For 2015-2022, 9.8% of the hourly data were selected as influenced by SI events. The systematic analysis of the SI effect on CO2 revealed differences between vegetative and non-vegetative seasons: during May-September, air masses from the stratosphere were richer in CO2 (+1.2 ± 1.3 ppm, average ± 1σ). On the contrary, during the cold months, air masses from higher altitudes were characterized by a lower amount of CO2 (-1.2 ± 0.8 ppm). Furthermore, SI events were usually characterized by an overall decrease in the CH4 compared to the remaining data throughout the solar year (with averaged values ranging from -7.6 to -16.1 ppb as a function of the seasonal period). However, based on the analysis of seasonal anomalies of residuals, it looks that SI events did not play a major role in determining the interannual variability of CO2 and CH4 at CMN.


290 Forest and grassland potential response to changing climate conditions: quantifying carbon and water flux dynamics in Central Germany

Poster

Flávio Bastos Campos1*, Corinna Rebmann2, Felix Pohl1, Anke Hildebrandt1

1UFZ (Helmholtz-Zentrum für Umweltforschung), Leipzig, Germany. 2KIT (Karlsruher Institut für Technologie), Karlsruhe, Germany

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

In climate-change context, characterized by increasing temperatures and frequent drought events, understanding the response of ecosystems' carbon and water fluxes becomes essential. This study aims to evaluate the carbon (C) and water flux dynamics in two distinct ecosystems, mixed deciduous forest (Hohes Holz, DE-HoH) and extensively managed grassland on drained peatland (Am Großen Bruch, DE-GsB), in Central Germany. Here we aim to understand which environmental drivers influence fluxes, and identify potential C sinks, particularly under drought. Eddy covariance towers at both sites have monitored fluxes since 2015, revealing divergent carbon and water flux responses between ecosystems. The forest site was a consistent C sink throughout this period (-360 ± 71 gC a-1). However, the grassland transitioned from C source to sink in some years (+176 ± 191 gC a-1, excluding lateral flows, e.g, fertilization, harvests) with elevated net ecosystem exchange (NEE) in 2019 (+442 gC a-1). In terms of Evapotranspiration (ET), both sites presented stable sums, around 557 ± 23 mm a-1 in forest and 391 ± 19 mm a-1 in grassland. Air and soil temperature, VPD, and net radiation exerted significant influence on ET and carbon uptake. NEE was strongly related to meteorological drivers in forest compared to grassland. Differential responses of NEE and ET indicate distinct ecosystem water use efficiency. Further research incorporating structural attributes and additional data (e.g., leaf area, biomass), particularly during drought periods, is justified to enhance our understanding of ecosystem responses to climate change-induced stress events and the role of ecosystem structure therein.


291 Transparent Horizons: IMEO's Methane Data Empowering Global Action

Oral

Andreea Calcan1*, Daniel Zavala-Araiza2, Steven P. Hamburg2, Xuefei Li1, Stefan Schwietzke2, James L. France2, Cynthia Randles1, Marci R. Baranski1, Meghan Demeter1, Robert Field1, Manfredi Caltagirone1

1International Methane Emissions Observatory, United Nations Environment Program, Paris, France. 2Environmental Defense Fund, Office of the Chief Scientist, Utrecht, Netherlands

Session 13. In situ data for climate and other environmental services and policy support

Ambition on methane emissions reduction is growing, and open, reliable, measurement-based and actionable data is essential to track changes in emissions over time. The ability of countries and companies to meet their goals relies on their ability to target action at the speed and scale required, as well as being able to demonstrate progress towards these goals. 

As a core implementing partner of the Global Methane Pledge, the UN Environment Programme’s International Methane Emissions Observatory (IMEO) has been tasked with creating a sound scientific basis for methane emissions estimates and is providing reliable, public, policy-relevant data to facilitate actions to reduce methane emissions. IMEO is collecting and integrating diverse methane emissions data streams, including satellite remote sensing data, science studies, national inventories, and measurement-based industry reporting to establish a global, centralized public record of empirically verified methane emissions.

Here, we will show the progress of IMEO towards developing its global, public dataset of policy-relevant methane data, highlighting successful mitigation case studies from the pilot phase of IMEO’s Methane Alert and Response System (MARS), and from IMEO’s Methane Science Studies around the world across multiple anthropogenic methane emission sectors. We demonstrate how empirical data can drive real, tangible mitigation action in countries. We will also open the discussion on how IMEO could potentially collaborate with other research infrastructures such as ICOS.


292 Quantifying biogenic CO2 fluxes in urban areas using field observations

Poster

Stavros Stagakis1*, Sophie Emberger2, Laura Bignotti3, Junwei Li4, Benjamin Loubet3, Jia Chen4, Matthias Mauder5, Nina Buchmann2, Markus Kalberer1

1Department of Environmental Sciences, University of Basel, Basel, Switzerland. 2Department of Environmental Systems Science, ETH Zürich, Zurich, Switzerland. 3ECOSYS, Université Paris-Saclay, INRAE, AgroParisTech, Palaiseau, Université Paris-Saclay, Paris, France. 4Department of Electrical Engineering, Technical University of Munich, Munich, Germany. 5Institute of Hydrology and Meteorology, Technical University of Dresden, Dresden, Germany

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

The natural processes of photosynthetic CO2 uptake and plant-soil respiration, often described by the term biogenic CO2 fluxes, are seldomly considered in the annual urban greenhouse gas inventories, assuming minor contributions compared to the anthropogenic emissions. Nevertheless, the introduction of observation-based emission monitoring approaches requires high temporal resolution flux estimations (e.g. hourly) where urban biogenic CO2 fluxes can significantly affect the anthropogenic emissions (e.g. during summer daytime hours). Several ecosystem models have been recently used to simulate the urban biogenic CO2 fluxes in high spatiotemporal resolution, but their performance is mainly evaluated in natural ecosystems using eddy covariance flux observations. Their effectiveness in the urban environment remains largely unknown.
 This study presents a new approach for the estimation of hourly urban biogenic CO2 fluxes based mainly on field observations, designed for the ICOS-Cities project, and applied on several locations of Zurich, Munich and Paris. The approach depends on continuous observations of tree sap flow, soil temperature, soil water content, phenology imagery, and local meteorology, as well as regular field campaign measurements of tree leaf area index and soil-leaf gas exchanges. These observations are used to derive key ecophysiological parameters and calibrate empirical environmental response functions to estimate hourly biogenic CO2 fluxes representative of the measurement locations. The fluxes are compared between locations and cities to identify possible effects of urban surroundings and management practices on the urban biospheric processes. The potentials and limitations of the approach are discussed in the perspective of future applications in urban greenhouse gas observatories.


293 Evidence of ongoing SF6 emissions in Germany

Poster

Katharina Meixner1*, Andreas Engel1, Tanja Schuck1, Thomas Wagenhäuser1, Cedric Couret2, Kieran Stanley3, Alistair Manning4, Jordan Armin5, Xochilt Gutièrrez5, Tobias Kneuer6,7, Dagmar Kubistin6,7, Matthias Lindauer6,7, Jennifer Müller-Wiliams6,7

1Goethe University Frankfurt, Frankfurt am Main, Germany. 2Umweltbundesamt, Zugspitze / Schneefernerhaus, Germany. 3University of Bristol, Bristol, United Kingdom. 4UK Met Office, Bristol, United Kingdom. 5Max Planck Institute for Biogeochemistry, Jena, Germany. 6Hohenpeissenberg Observatory, Hohenpeissenberg, Germany. 7Deutscher Wetterdienst, Hohenpeissenberg, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Sulfur hexafluoride (SF6) is a potent greenhouse gas with a Global Warming Potential (GWP) of 24,700 over 100 years and is used mainly in electrical switchgear. Several global and regional measurement networks, including the AGAGE, NOAA, GAW and ICOS programmes, have been measuring surface-based SF6 for several years. These measurements and inverse modelling have shown that there are still significant SF6 emissions in Western Europe, with the largest source estimated to be in southern Germany. Time series of SF6 in Germany are available from the following stations: Taunus Observatory (AGAGE), Zugspitze / Schneefernerhaus (UBA Germany, GAW, ICOS), Karlsruhe (DWD, ICOS), Hohenpeissenberg (DWD, GAW, ICOS), Lindenberg (DWD, ICOS), Ochsenkopf (MPI-BGC, ICOS), Steinkimmen (ICOS) and Gartow (ICOS).

This distribution of observation sites provides good spatial and temporal resolution of the atmospheric SF6 dry mole fraction in Germany. The observation of persistently elevated mixing ratios is indicative of continuing local emissions in Germany. Depending on the wind direction, the highest levels of SF6 were measured at Zugspitze, Karlsruhe and the Taunus Observatory.  The Karlsruhe station stands out with maximum mixing ratios of over 70 ppt under easterly wind conditions.

In addition to the analysis of such pollution events, the observations are also used together with other ICOS and AGAGE sites in Europe in the top-down inverse model InTEM (Inversion Technique for Emission Modelling) coupled to the atmospheric transport model NAME (Numerical Atmospheric Dispersion Modelling Environment). The initial model results identify a source in Southwest Germany accounting for approximately 35% of German SF6 emissions.


294 Anthropogenic emissions measured with eddy covariance in two “climate-neutral by 2030” nearby italian cities

Poster

Simone Putzolu*, Tommaso Giordano, Lorenzo Brilli, Valentina Marchi, Alessandro Zaldei, Carolina Vagnoli, Giovanni Gualtieri, Beniamino Gioli

Consiglio Nazionale delle Ricerche, Firenze, Italy

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Eddy covariance flux measurements in urban environments are presented in two adjacent cities (Firenze and Prato, Italy) among the EU 100 climate-neutral cities by 2030, for the past three years. These cities have similar land use distribution and urban neighborhood morphology, with almost fully anthropized footprint surfaces but different pressures from residential, commercial and tourism sectors. Hourly diurnal cycles were well correlated between the two sites during the cold season (r = 0.94) while were not correlated during the warm season. Yearly seasonal patterns at weekly scale were also very well correlated (r >0.9), and showing peak to mean ratios of 0.75 and 0.93 in Firenze and Prato respectively. These patterns reflect a similar temporal distribution of natural gas heating usage. By contrast, total emissions were always higher in Firenze: while in 2021 emissions were 34% higher, they were 52% higher in 2023. The emission gap between the two cities increased in the last 3 years, mostly as a consequence of the increasing touristic pressure in Firenze, while they maintained basically stable at Prato, which was not subject to such pressure. This observed pattern poses a challenge in choosing pathways toward carbon neutrality, indicating that along with infrastructural interventions, also citizen pressure, both residential and touristic, should be carefully considered in designing emission reduction policies in many European cities.


295 GBOV (Copernicus Ground-Based Observation for Validation): an overview of the service.

Oral

Christophe Lerebourg*, Rémi Grousset

ACRI-ST, Sophia Antipolis, France

Session 13. In situ data for climate and other environmental services and policy support

GBOV (Copernicus Ground-Based Observation for Validation), is an element of CLMS (Copernicus Land Monitoring Service ; https://land.copernicus.eu). Its main purpose is to collect worldwide ground data to support Copernicus Land Service validation strategy. The Land service provides a wide range of bio-geophysical parameters including soil moisture, snow, temperature, reflectance, vegetation and water bodies. GBOV focuses on seven core land service products (TOC-R, Albedo, LAI, FAPAR, FCOVER, SSM and LST), five of whom are listed among GCOS Essential Climate Variables (ECV). 

ICOS is one of the main sources of ground data to GBOV together with other networks like BSRN, NEON, TERN, SurfRad etc. Ground measurements (the so-called “Reference Measurements”) cannot be directly used for satellite data validation mostly because of ground heterogeneity: the footprint of a ground sensor is generally not comparable to a satellite pixel. Up-scaling procedures have to be applied to these ground measurements in order to generate a measurement comparable to a satellite pixel, the so-called “Land Products”. GBOV service is freely accessible on https://land.copernicus.eu/global/gbov and provides Land Products over 112 sites. 

GBOV additionally deploys its own instruments as part of collaborations with the existing networks. Seven ground stations have been upgraded with additional instrumentation since 2018. In 2024, a vegetation station has been installed over Fontainebleau research station (France). Fuji Hokuroku (Japan) and Litchfield (TERN network Australia) will receive a GBOV LST station in 2024. 

 

296 Measurements and calibration for high precision continuous monitoring of stable isotope ratios in atmospheric methane

Oral

Christopher Rennick1*, Emmal Safi1, Cameron Yeo1, Emily Hopkinson1, Ruth Pearce1, Tim Arnold1,2

1NPL, Teddington, United Kingdom. 2University of Edinburgh, Edinburgh, United Kingdom

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Uptake of continuous monitoring of δ13C and δ2H isotope ratios in atmospheric methane is limited by the difficulty in making high-quality measurements with sufficient precision. Optical isotope ratio spectroscopy (OIRS) has the potential to provide measurements needed for emissions source sector disaggregation but is limited by the availability of suitable reference materials, and the traceability of in-field calibration.

We will present the measurement system and calibration protocols developed for δ13C(CH4) and δ2H(CH4) measurements by Boreas, an automated cryogenic preconcentrator and laser spectrometer, developed at NPL. The calibration strategy uses synthetic reference materials prepared gravimetrically from a single high-purity CH4 parent, alongside a single compressed air standard. Both the parent methane and compressed air methane are isotopically characterised by IRMS. Other CH4 mixtures are used to validate the calibration, and we will show that the combined uncertainty of a measured isotope ratio is dominated by the contribution from the isotope ratio of the high-purity CH4 parent. We also quantify the uncertainty budget over the amount fraction and isotopic composition ranges of the instrument.

The system was deployed in 2021 to tall tower observatory located south of London at Heathfield, a GAW regional station for continuous regional-scale monitoring of CH4 isotope ratio. We will show the calibrated δ13C(CH4) and δ2H(CH4) timeseries, which displays significant variation from baseline during pollution episodes with changes typically resulting from a mixture of sources.


297 A Vegetation Photosynthesis and Respiration Model (VPRM) for the post-MODIS era

Poster

Theo Glauch1,2*, Julia Marshall2, Christoph Gerbig3, Andre Butz1

1Heidelberg University, Heidelberg, Germany. 2German Aerospace Center (DLR), Weßling, Germany. 3Max Planck Institute for Biogeochemistry, Jena, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The data-driven VPRM model is a simple light-use-efficiency model, driven by satellite-derived indices of Enhanced Vegetation Index (EVI) and Land Surface Water Index (LSWI) to extract information at high spatial resolution. High temporal resolution is provided through meteorological driving data, namely 2-m temperature and shortwave radiation at the surface. Four parameters per vegetation type are fit using eddy flux tower measurements. VPRM is widely used to model carbon exchange between the land biosphere and the atmosphere. A common application is as a background (prior) model for estimating carbon fluxes through inversion techniques at regional scales, given the high temporal and spatial resolution of the fluxes compared to complex process models.
 
 Historically, VPRM relied on data from the 500-m-resolution MODIS satellite and a static 1-km land cover classification map. As MODIS approaches discontinuation, we present an updated VPRM software framework - pyVPRM - capable of handling satellite data from MODIS, VIIRS, and Sentinel-2, as well as high-resolution land cover products, e.g. ESA WorldCover or the Copernicus Global Land Service. The extremely high spatial resolution of the Sentinel-2 reflectances and updated land cover maps now allows vegetated area within cities and crop fields to be resolved. In addition, the framework naturally provides an interface to generate VPRM inputs for use in online mesoscale models, such as the greenhouse gas module of the Weather Research and Forecasting Model (WRF). In our presentation we provide an overview of the new model and show exemplary applications across Europe from city to continental scale.
 

298 A new age of autonomous marine carbon system observations: An evaluation of in situ Lab-On-Chip carbonate sensors in recent applications

Oral

Emily Hammermeister1,2*, Socratis Loucaides1, Efstathios Papadimitriou1, Allison Schaap1, Maggie Johnson3, Vincent Saderne3, Edward Chaney1

1National Oceanography Centre, Southampton, United Kingdom. 2University of Southampton, Southampton, United Kingdom. 3King Abdullah University of Science and Technology, Thuwal, Saudi Arabia

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

In a world where the climatic response to human carbon emissions has reached a critical point in time, understanding the ocean’s role in carbon cycling has become a major focus for scientific observation and intervention. The development of marine autonomous platforms and in situ sensing provides observations of higher spatiotemporal resolution which can be used to further measure, characterize, and model ocean carbon. Additionally, the versatility of autonomous technology affords us the ability to adapt its application to measure different environments and ocean processes. Here, we present results from a range of observing applications using novel Lab-On-Chip (LOC) pH and Total Alkalinity (TA) sensors integrated onboard autonomous platforms and discuss methods for data processing and quality control. Examples include pH and TA data collected by the Autosub Long Range (ALR) Autonomous Underwater Vehicle (AUV) (Boaty McBoatface) on the Celtic Shelf margin where pH and TA LOC sensors were used to constrain the carbonate system of the water column across different physical and biogeochemical gradients. Results will also be presented from the ALR’s longest continuous deployment on record- spanning over 2000 km over 5 weeks with pH sensors onboard. Finally, we will demonstrate the potential of these technologies for characterising coral reef biogeochemistry and carbonate system dynamics following recent moored deployments in the central Red Sea. Based on the collected data and our experience in the field, the performance of this new technology and its potential as a tool for ocean CO2 observations will be broadly evaluated.


299 Trainou super site for measuring greenhouse gases in Europe, combining ICOS, TCCON and AIRCORE

Oral

Michel Ramonet1*, Morgan Lopez1, Louis-Jeremy Rigouleau1, Thorsten Warneke2, Cyril Crevoisier3, Céline Lett4, Thomas Laemmel5, Julien Moye1, Dylan Lopez1, Massaer Kouyaté1, Francois-Marie Bréon1

1Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France. 2Institute of Environmental Physics, University of Bremen, Bremen, Germany. 3Laboratoire de Météorologie Dynamique, LMD/IPSL, CNRS, Ecole polytechnique, Palaiseau, France. 4Luxembourg Institute of Science and Technology, Department of Environmental Research and Innovation, Belvaux, Luxembourg. 5Department of Chemistry, Biochemistry and Pharmaceutical Sciences and Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

The Trainou Tower station (TRN) is located in a rural area in France (47°57’53”N, 2°06’45”E), hundred kilometers south of Paris. Greenhouse gas (GHG) monitoring at this tower was initiated in spring 2007 as part of the European CHIOTTO project, and integrated into the European ICOS network in 2017. Concentrations of CO2, CH4, N2O and CO are measured continuously at 4 sampling heights (5, 50, 100, 180m). The surface program was supplemented by measurements of total GHG columns in 2009, as part of the TCCON network (Orléans site), and by regular measurements of AIRCORE vertical profiles, up to 25 km, since 2018. This co-location of infrastructures dedicated to GHG measurements, unique in Europe, enables us to analyze the coherence and complementarity of these three observation methods. We will present the seasonal cycles and long-term trends deduced from Trainou observations, at different altitudes from the surface to the stratosphere. Total columns of CO2, CH4, N2O and CO estimated by combining in-situ vertical profiles from the ICOS tower and Aircores, will be compared with columns measured by remote sensing from the ground (TCCON) and space. Trainou's datasets will be compared with simulations from various atmospheric transport models (CAMS, LMDz, TM3) to assess the benefits of co-locating observation programs, and to evaluate the ability of these models to reproduce observations in a rural area regularly disturbed by emissions from the Paris region.


300 From tree to forest: how extreme events alter growth and water status - a six year study

Poster

Fran Lauriks*

University of Antwerp, Antwerp, Belgium

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Heat waves and dry spells are increasing in intensity and frequency as a result of climate change. Despite their alarming relevance, impact of these events on tree and ecosystem responses remain poorly understood. Over the past six years point dendrometers have monitored tree growth and water status of five pine (Pinus sylvestris L.) trees at the ICOS forest site in Brasschaat. In parallel gross primary production, net ecosystem exchange, and latent heat fluxes were estimated using the eddy covariance method. From 2018 to today the forest was exposed to a sequence of extreme events including the 2018, 2020 and 2022 heat wave and the 2021 wet summer. Individual datasets provide important information on overall responses and recovering ability of single trees and the forest during and after these events. Combination of these two data sets provides a unique insight in the temporal variability of the contribution of trees to forest carbon and water fluxes over the growing season and allows evaluation of this contribution during extreme events.


301 Estimating air-sea CO2 fluxes  from an oceanographic tower in the Northern Adriatic Sea using ΔpCO2 and wind/wave measurements

Poster

Silvio Davison1*, Alvise Benetazzo1, Mauro Bastianini1, Carolina Cantoni2

1CNR-ISMAR, Venice, Italy. 2CNR-ISMAR, Trieste, Italy

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

The Northern Adriatic Sea is a shallow, semi-enclosed sub-basin surrounded by an industrialized area in the northeast part of the Mediterranean Sea. Episodic high wind events in this region lead to intense air-sea fluxes and favour dense-water formation, which can absorb and sequester CO2.

In this context, the oceanographic research tower “Acqua Alta” run by CNR-ISMAR, which collects atmospheric and biogeochemical ocean data in the Northern Adriatic, has been recently equipped with continuous measurements of atmospheric and surface-water partial pressure of CO2 (pCO2) to assess air-sea CO2 fluxes at this site. As for the surface forcings, given the pivotal role of wave breaking in the exchange rate of gases between the atmosphere and the ocean, measurements of surface waves and penetration depth of entrained air bubbles were also collected with an underwater ADCP echosounder. The combined dataset allows estimates of air-sea CO2 exchanges using parametrizations for the gas transfer velocity k not based solely on wind speed but also accounting for bubble-mediated effects due to wave breaking. 

The set of measurements at the Acqua Alta tower over a 1-year period shows a seasonal cycle of pCO2, where surface waters are under-saturated with respect to the atmosphere in the winter months, acting as a strong sink of CO2, with enhanced air-sea fluxes up to 80 mmol m-² d-¹ during strong northeasterly (Bora) wind events. Conversely, during summer, the temperature-driven increase of surface water pCO2 shows a slight over-saturation and a much larger variability due to the particularly large summer variability of wave climate in this region and the increased biological activity.


302 Assessing atmospheric fossil fuel emissions using 14CO2 measurements and global atmospheric simulations with the CIF-LMDZ transport and inverse modeling system

Poster

Hannah Allen1*, Yilong Wang2, Frédéric Chevallier1, Susanne Preunkert3, Samuel Hammer3, Antoine Berchet1, Adrien Martinez1, Joel Thanwerdas4, Elise Potier5, Philippe Ciais1, Gregoire Broquet1

1Laboratoire des Sciences du Climat et de l’Environnement, CEA CNRS UVSQ, Gif-sur-Yvette, France. 2State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China. 3Institut für Umweltphysik, Heidelberg University, Heidelberg, Germany. 4Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland. 5Science Partners, Paris, France

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Independent monitoring and apportioning of CO2 emissions is crucial for the verification of greenhouse gas reductions targeted by international agreements designed for climate change mitigation and adaption.  Radiocarbon (14C), found as a fractional isotope of CO2, can be used as a key tracer for fossil-derived CO2 and thus aid in the accurate apportioning of measured CO2 that arises from fossil fuel sources compared with other emissions sources.  As part of the Horizon Europe CORSO project, we are developing a dedicated atmospheric transport modeling and variational inversion configuration to assess fossil CO2 emissions estimates at global to regional scales based on the assimilation of CO2 and 14CO2 measurements that are collected using central-European atmospheric ICOS stations combined with global background stations.  The modeling and inversion framework is based on the Community Inversion Framework (CIF) coupled to the LMDZ global transport model with fluxes and isotopic signatures from terrestrial, oceanic, fossil fuel, nuclear, and cosmogenic sources.  We conduct a multi-decadal analysis of the CO2 and 14CO2 emissions derived from this framework.
 

303 Ship-borne atmospheric measurements of CH4 concentration and 𝜹13C-CH4 contribute to detect Arctic CHsources during the MOSAiC expedition

Poster

Samuel Sellmaier1*, Ellen Damm1, Torsten Sachs2,3, Annette Rinke1, Inge Wiekenkamp2, Benjamin Kirbus4, Astrid Lampert5, Markus Rex1

1Alfred-Wegener-Institute Helmholtz Centre for Polar and Marine Sciences, Potsdam, Germany. 2GFZ German Research Centre for Geosciences, Potsdam, Germany. 3Institute of Geoecology, TU Braunschweig, Braunschweig, Germany. 4Leipzig Institute for Meteorology (LIM), Leipzig University, Leipzig, Germany. 5Institute of Flight Guidance, TU Braunschweig, Braunschweig, Germany

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Quantifying source dynamics of methane (CH4) in the Arctic is crucial to understand the global methane budget, yet it is hindered by challenges arising from the remote location and the diversity of CH4 sources. This study presents ship-borne time series of CH4 concentration and 𝜹13C-CH4 values continuously recorded with a Picarro G2132-Isotope Analyser during Leg 4 (June/July 2020) and Leg 5 (August/September 2020) of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in the Central Arctic. Three approaches to filter contamination by local pollution sources on both time series were compared. Finally, the Pollution Detection Algorithm was applied to the raw data. 
 Using five days air mass backwards trajectories modelled with LAGRANTO and ERA5 wind fields we connected the observed data to specific air mass source areas and transport pathways within the atmospheric boundary layer. We used the Keeling plot approach to identify isotopic fingerprints of the air mass source areas and seasonal variations of CHsources in specific air mass source areas. Our analysis reveals that variations in the time series are related both to specific geographical source areas and to seasonally different distinct CH4 source strengths within some source areas. The findings highlight the importance of considering air mass source areas and seasons to understand variations in CH4 concentration and 𝜹13C-CH4 values in the Arctic. The study suggests the need for further collection of CH4 concentration and 𝜹13C-CH4 data within the distinct airmass source areas and considering local properties.

 

304 Disentangling the role of plant phenology in regulating methane emissions from a northern peatland: results from a 10-year data archive

Poster

Gillian Simpson*, Koffi Dodji Noumonvi, Järvi Järveoja, Mats B. Nilsson, Matthias Peichl

Swedish University of Agricultural Sciences (SLU), Umeå, Sweden

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Northern peatlands are a globally important source of methane (CH4), a potent greenhouse gas. However, current estimates of these emissions are poorly constrained due to their strong spatiotemporal variability and a lack of long-term datasets. While studies at the plot-level (0.1-1 m2) have shown that the presence of aerenchymous plant species can explain CH4 emissions spatially; routine measurements of temperature and water-table depth have commonly been employed to explain temporal variability in emissions. However, as CH4 is produced from plant substrate, the seasonal development of vegetation or ‘phenology’ is likely to be another important driver of emissions. Understanding how plant development affects CH4 production over the growing season is key for improving process-based models of CH4 emissions, but has so far been hampered by a lack of continuous phenology data. This study employs a unique 10-year archive of eddy-covariance measurements and phenocam imagery to disentangle the role of peatland phenology in regulating temporal variability of CH4 emissions at the ICOS Degerö peatland, northern Sweden. We use path analysis to better understand the network of biotic and abiotic drivers of peatland CH4 emissions, and how these drivers vary over the course of the growing season. These findings are key to reducing uncertainty in estimates of current and future CH4 emissions from these ecosystems.


305 Impact of diversity on GHG exchange on an agricultural field: a comparison study between barley monoculture and barley with undersown species in Finland

Poster

Stephanie Gerin1*, Liisa Kulmala1, Annalea Lohila1, Mika Korkiakoski1, Henriikka Vekuri1, Helena Rautakoski1, Laura Heimsch1, Jussi Heinonsalo2, Jari Liski1

1Finnish Meteorological Institute, Helsinki, Finland. 2University of Helsinki, Helsinki, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Globally, agricultural land represents ca. 38% of the Earth’s land surface, with one-third allocated to croplands and two-thirds to meadows and pastures. Around 17% of total anthropogenic greenhouse gas emissions derive from agriculture and related land use. While the intensification of agriculture has improved food security, it has harmed the environment in many aspects.  

Despite the negative impact of agriculture so far, there are practices which could be less harmful for climate and biodiversity. For example, climate-friendly practices can help increase carbon sequestration and reduce CH4 and N2O emissions. However, there is a need to quantify and verify the impact of these practices compared to traditional practices.

To bridge part of this gap, the TWINWIN experiment was established in Helsinki in June 2019 to study the impact of diversity on various soil-plant-atmosphere variables such as soil micro-organisms, greenhouse gases, plant diseases, and many more. The experiment consisted of 60 plots where barley was sown as monoculture or with 1 to 8 undersown species. The eight undersown species varied in functional traits, such as rooting depth and nitrogen-fixing properties.

Here, we will present the TWINWIN experiment with a focus on CO2, CH4 and N2O fluxes measured with the chamber technique in 2020-2022. While no major differences were observed during the main growing season, notable and significant differences were observed outside the growing season. 


306 Estimation of the fossil-fuel fraction of CO2 measured in Paris based on radiocarbon, and co-emitted species (NOx, CO, BC)

Oral

Ingrid Chanca1,2,3*, Laura Bouillon1, Nicolas Bonnaire1, Markus Eritt3,4, Lorna Foliot1, Cécile Gaudry1, Valérie Gros1, Xochilt Gutierrez3,4, Samuel Hammer5,6, Carmen Kalalian7, Guillaume Nief1, Jean-Eudes Petit1, Michel Ramonet1

1Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France. 2Laboratório de Radiocarbono, Universidade Federal Fluminense, Niterói, Brazil. 3Max Planck Institute for Biogeochemistry, Jena, Germany. 4ICOS Flask and Calibration Laboratory (ICOS-FCL), Jena, Germany. 5Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany. 6ICOS Central Radiocarbon Laboratory (ICOS-CRL), Heidelberg, Germany. 7Université Paris-Saclay, INRAE, AgroParisTech, UMR EcoSys, Palaiseau, France

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Urban and industrial areas are major contributors to global fossil fuel CO2 (ffCO2) emissions, but accurately quantifying these emissions is challenging. The PAUL (ICOS-Cities) project in Paris has been using ambient air sampling since March 2023 to estimate radiocarbon (14C)-based ffCO2 levels. Samples are collected from a background station (Meudon, MEU) located in a forested area southwest of Paris, and a signal station (Romainville, ROV), positioned approximately 20 km northeast of MEU, based on the dominant wind direction; Air samples are collected into flasks by automated samplers (MEU: RINGO; ROV: ICOS flask sampler). The sampling strategy follows a Lagrangian approach and samplings are conducted when an air mass crosses the urban area of Paris, i.e. passing by both sites within a radius of 5 km. High-precision measurements of 14C-CO2 and co-emitted species (NOx, CO, BC) in situ and/or flasks were used to estimate the anthropogenic fraction of CO2 emissions in Paris. NOx, CO, and BC measurements are used as tracers for specific sources (e.g. traffic, heating). Based on ∆14C-CO2 and CO2 concentrations for pairs collected between March and September 2023, ffCO2 estimates vary between 0.5 and 5.4 ppm (median = 1.6 ppm) in both spring and late summer. The variation in CO2 concentration ranged from 1 to 6.8 ppm. In June/July, ffCO2 estimates vary from negative values to up to ca. 4 ppm. These findings provide valuable insights for comparing emission inventories and improving our understanding of urban carbon dynamics.


307 Fusion of PRISMA and Sentinel-2 imagery with biophysical models for plant functional retrievals in ICOS sites across Europe

Poster

Jose Luis Pancorbo1*, Paul Mille2, Giandomenico De Luca1, Beniamino Gioli1, Nicola Arriga3, Flor Álvarez-Taboada2, Pieter S.A. Beck3, Lorenzo Genesio1, Carlos Camino3

1National Research Council—Institute of BioEconomy (CNR-IBE), Florence, Italy. 2School of Agrarian and Forest Engineering, Universidad de León, León, Spain. 3Joint Research Centre (JRC), European Commission (EC), Ispra, Italy

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

Plant functional traits retrievals with earth observation systems provide crucial insights into photosynthesis rate, plant health or gross primary production (GPP). Variations in the retrieved parameters may indicate biotic or abiotic disturbances such as pest outbreak, seasonality variations, or drought. Harmonizing information of the hyperspectral PRISMA satellite with the short revisit time of the Sentinel-2 (SE-2) mission allows leveraging their capabilities for plant traits monitoring. This study assesses a hybrid machine learning (ML) approach coupling radiative transfer models (RTMs) and optical satellite imagery across different Integrated Carbon Observing System (ICOS) sites.

The specific objectives are i) to develop a hybrid ML framework to estimate key plant traits (e.g., leaf area index and nitrogen concentrations) by coupling PRISMA and SE-2 spectral resolution at the site of San Rossore 2 ICOS Ecosystem Station, Italy, ii) to utilize the plant traits derived with a SE-2 time series to monitor GPP fluctuations and detect the outbreak of Fomes fomentarius fungus in San Rossore and iii) to extend the ML methods to diverse forest ecosystems across Europe for comprehensive analysis, management and monitoring applications.

Findings demonstrate the effectiveness of the proposed PRISMA-SE-2 methods in estimating plant traits across a range of climate and forest ecosystems, including evergreen and deciduous forests, broadleaf and needleleaf forests, as well as mixed forests. Moreover, integrating the PRISMA spectral resolution within SE-2 time series enables accurate monitoring of GPP fluctuations in varied forest ecosystems. Notably, this approach facilitated the early detection of the fungal outbreak in the San Rossore forest.


308 Quantifying Arctic-Boreal methane emissions using atmospheric observations and a global inverse model

Oral

Luana S. Basso1*, Christian Rödenbeck1, Victor Brovkin2, Goran Georgievski2, Martin Heimann1, Mathias Göckede1

1Max Planck Institute for Biogeochemistry (MPI-BGC), Biogeochemical Signals, Jena, Germany. 2Max Planck Institute for Meteorology (MPI-MET), Climate Dynamics, Hamburg, Germany

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Wetlands and lakes are a major natural source of methane to the atmosphere in the Arctic-Boreal regions. Disturbance processes associated with the permafrost thawing, driven by accelerated temperature increases, hold the potential to increase methane emissions. This, in turn, may contribute to a positive feedback that exacerbates climate change. To address this uncertainty and to better understand the role of this region in the global methane budget, we estimated global methane fluxes using the Jena CarboScope Global Inversion System, with a special focus on the Arctic-Boreal region. As data availability in this target region has increased significantly over the last decades, our estimates focus on the time period of 2010 to 2021. We used the wetland flux from the JSBACH model as prior flux and assimilated globally available atmospheric observations (105 towers in total), with a particular focus on towers within the region between 60°N and 90°N latitude, to better constrain the Arctic-Boreal estimates (22 towers). The area of interest was divided into six different regions in order to compare prior and posterior fluxes, investigate regional and interannual variability, and examine seasonal patterns. Our results indicate pronounced emission peaks during the summer months, especially from July to September. In addition, we found regional variability in emissions, with the western region of Russia having the highest emissions. Finally, we compared our estimates with previous top-down CH4 estimates available for the same period.


309 Advancements in atmospheric methane clumped isotope measurements and modelling

Oral

Malavika Sivan*, Bibhasvata Dasgupta, Maria Elena Popa, Thomas Röckmann

Institute for Marine and Atmospheric Research Utrecht, Utrecht, Netherlands

Session 1. Isotopes and other tracers for studies of methane sources and sinks

The atmospheric mole fraction of methane, a potent greenhouse gas, has been rising since the 1800s, primarily due to anthropogenic emissions, while also displaying substantial multi-annual variability, with a notable stagnation period between 2000 and 2007. Various natural and anthropogenic sources, variations in the atmospheric OH concentration and other sink reactions influence the atmospheric methane concentration. Understanding the contribution of each of these factors is crucial for a comprehensive understanding of the global methane cycle. 

Recent studies have shown that measurements of the clumped isotopic composition (Δ13CH3D and Δ12CH2D2) may serve as an additional tool to constrain the sources or sinks of methane [1,2]. Technical developments towards low-concentration samples facilitate such measurements of methane extracted directly from ambient air. 

The first measurements of the atmospheric methane clumping anomalies show distinct signatures of about 1 ± 0.3 ‰ for Δ13CH3D and 44 ± 3 ‰ for Δ12CH2D2, strongly enriched in Δ12CH2D2 compared to all known sources [3,4]. However, these measurements reveal discrepancies with existing model predictions, highlighting significant knowledge gaps in the known clumped isotopic composition of the sources and sink fractionations. Therefore, we use atmospheric measurements, including the history of clumping anomalies reconstructed from firn air samples collected from Greenland, to develop a two-box atmosphere model that reproduces the measured values. Additionally, this optimized model is exploited to understand the influence of the different sources and sinks on atmospheric methane over time.  

References: 

  1. https://doi.org/10.1029/2020GB006883
  2. https://doi.org/10.1002/2017GB005655
  3. https://doi.org/10.1073/pnas.2305574120
  4. https://doi.org/10.5194/egusphere-2023-1906

 
 310 Bridging domains to enhance scientific synergy: The ICOS Carbon Portal in cross-RI collaborations

Poster

Angeliki Adamaki*, Alex Vermeulen, André Bjärby, Klara Broman, Claudio D'Onofrio, Anders Dahlner, Maggie Hellström, Ute Karstens, Harry Lankreijer, Arndt Meier, Oleg Mirzov, Jonathan Schenk, Ida Storm, Jonathan Thiry, Remco de Kok, Zhendong Wu, Zois Zogopoulos

Lund University-ICOS Carbon Portal, Lund, Sweden

Session 17. Best Practices in the landscape of Research Infrastructures: Cooperation, Co-location and other lessons learned

Collaboration across different scientific fields and organisations is thriving, especially in projects that aim to address complex environmental challenges. Multi- and inter-disciplinary approaches become essential when e.g. scientists from various backgrounds work together to understand and mitigate environmental risks, ensuring the safety and well-being of communities. Very often scientists need to combine data from diverse sources, to better understand climate patterns which would inform policies aimed at combating global warming. In other studies such as those for sustainable cities, researchers collaborate across disciplines to create solutions for environmentally friendly and resilient urban environments. The ICOS Carbon Portal, alongside other groups and initiatives, plays a crucial role in facilitating such collaboration. By providing tools for managing data and research outputs, it enables scientists to work together effectively across borders and disciplines. 

This presentation explores the role of the ICOS Carbon Portal in supporting efforts for collaboration within and beyond ICOS units, groups, and scientific communities. By reflecting on past experiences and achievements, this presentation offers insights into the opportunities and complexities of multi- and inter-disciplinary research and emphasizes the need for continued cooperation to address environmental concerns and drive scientific innovation.


311 Strengthening training and capacity building to improve global observations of atmospheric composition

Poster

Martin Steinbacher1*, Sergio Moreno2, Sara Basart2, Christoph Zellweger1, Lukas Emmenegger1

1Empa, Duebendorf, Switzerland. 2WMO, Geneva, Switzerland

Session 16. Continuous Learning in a changing world - Teaching and learning novel tools & methods used for measurement techniques’, data & policy

The availability of long-term, high-quality atmospheric composition observations is highly unbalanced around the globe. Thanks to a well-established tradition, funding mechanisms, and research infrastructures such as ICOS, observations are mainly available in developed northern hemisphere countries, but are often sparse in other regions.
 The Global Atmosphere Watch (GAW) programme, coordinated by the World Meteorological Organization (WMO), is dedicated to providing consistent long-term observations of the chemical composition of the atmosphere on a global scale. Emphasizing rigorous quality assurance and control measures, GAW plays a pivotal role in understanding atmospheric dynamics and their implications. The new GAW Science and Implementation Plan 2024 – 2027 defines Capacity Development as one of the four major strategic objectives of the programme.
 This presentation will reflect on the progress in capacity development made to date within GAW, highlight recent activities, and discuss key challenges and how they may be addressed. Furthermore, we will outline the evolving role of GAW Capacity Development. The latter involves improved post-training monitoring, expanding regional training facilities and increasing the use of online educational material, which are complementary to traditional in-person and on-site courses.
 We advocate the significance of GAW observations and identify synergies with other programmes. This consolidated approach not only fortifies GAW's mission but also serves as a blueprint for WMO's forthcoming Global Greenhouse Gas Watch (G3W) initiative. G3W is an ambitious endeavor, which seeks to bolster the global greenhouse gas observing system and furnish actionable insights to stakeholders, particularly the United Nations Framework Convention on Climate Change (UNFCCC).
 


312 Spring melting season methane emissions in the northern high latitude wetlands based on inversion modeling

Oral

Sara Hyvärinen*, Maria Tenkanen, Aki Tsuruta, Anttoni Erkkilä, Kimmo Rautiainen, Tuula Aalto

Finnish Meteorological Institute, Helsinki, Finland

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

In the high northern latitudes there are extensive wetlands, which are a source of methane. Methane emissions are characterized by a seasonal cycle corresponding to freezing and thawing of the ground. Much of the high northern latitudes are also covered by permafrost. As permafrost thaws due to climate change, these methane emissions may increase. There is still much uncertainty about methane emissions and their seasonality in these wetlands. 

During the spring melting season, methane emissions increase rapidly. To gain a better understanding of emissions during this spring shoulder season, the melting season was defined using using the SMOS F/T soil state for both permafrost and non-permafrost regions for the years 2011-2021. The SMOS F/T soil state daily information on the freezing state of the soil in the northern latitudes. Methane emissions during the melting period were determined using the inversion model CarbonTracker Europe – CH4 by assimilating in-situ measured methane mole fractions including those from the ICOS stations. The emissions were found to be relatively small compared to annual emissions, with the non-permafrost region having substantially larger emissions than the permafrost regions. To understand the emissions better, the relationship between different drivers, such as the length and mean temperature of the melting season, was studied. A negative correlation between mean temperature and length, and a positive correlation between length and emissions were found.


313 EYE-CLIMA: A Horizon Europe project to support national inventories for emissions of climate forcers

Poster

Rona Thompson1*, Andreas Stohl2, Philippe Peylin3, Philippe Ciais3, Hartmut Boesch4, Tuula Aalto5, Antoine Berchet3, Maria Kanakidou6, Wilfried Winiwarter7, Glen Peters8, Dmitry Shchepashchenko7, Jean-Pierre Change9, Roland Fuss10, Ignacio Pisso1, Richard Engelen11, Almut Arneth12, Nina Buchmann13, Stefan Reimann14, Stephen Platt1, Nalini Krishnankutty1

1NILU, Kjeller, Norway. 2University of Vienna, Vienna, Austria. 3LSCE, Gif sur Yvette, France. 4University of Bremen, Bremen, Germany. 5FMI, Helsinki, Finland. 6University of Crete, Heraklion, Greece. 7IIASA, Vienna, Austria. 8CICERO, Oslo, Norway. 9CITEPA, Paris, France. 10Thuenen Institute, Braunschweig, Germany. 11ECMWF, Reading, United Kingdom. 12KIT, Garmisch, Germany. 13ETHZ, Zurich, Switzerland. 14EMPA, Duebendorf, Switzerland

Session 13. In situ data for climate and other environmental services and policy support

National greenhouse gas inventories (NGHGIs) and Biennial Transparency Reports (BTRs) on emissions and removals are crucial elements of the Paris Agreement and its Global Stocktake. However, NGHGIs are subject to significant uncertainties, owing to uncertain emission factors and/or insufficient activity data. Additional and complementary information can be provided from atmospheric inversions, which use atmospheric observations in a statistical optimization framework to estimate emissions and removals. This method of verification is referred to in the 2006 IPCC Guidelines on national reporting and the 2019 refinement. However, atmospheric inversions have been hitherto considered too complex and inaccurate at national scales to be widely used for this purpose.

EYE-CLIMA is a Horizon Europe project that aims to develop the atmospheric inversion methodology to a level of readiness where it can be used to support the verification of NGHGIs. The overarching goals are to: i) develop a best practice in atmospheric inverse modelling for estimating emissions at national scale, including full assessment of uncertainties, ii) develop the methodology on how to prepare sectorial emission estimates from atmospheric inversions and make these comparable to what is reported in NGHGIs, iii) work together with NGHGI agencies on projects piloting the EYE-CLIMA methodology of emissions verification and iv) develop international best practices for the quality control of NGHGIs. EYE-CLIMA covers CH4, N2O, 5 HFC species, SF6, and the black carbon (BC) aerosol. This presentation will focus on the set-up of the EYE-CLIMA project and provide an overview of the first results in support of NGHGI verification.


314 Remote sensing measurements of greenhouse gases at Sodankylä and comparisons with satellite observations

Poster

Rigel Kivi1*, Pauli Heikkinen1, Juha Hatakka2, Hannakaisa Lindqvist1, Huilin Chen3

1Finnish Meteorological Institute, Sodankylä, Finland. 2Finnish Meteorological Institute, Helsinki, Finland. 3Nanjing University, Nanjing, China

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

At Sodankylä, Finland (67.37° N, 26.63° E) regular measurements of greenhouse gases have been performed using remote sensing techniques. The Sodankylä site participates in the Total Carbon Column Observing Network (TCCON), the Network for the Detection of Atmospheric Composition (NDACC), the COllaborative Carbon Column Observing Network (COCCON) and other ground-based networks. The ground-based measurements are frequently used to support the satellite-borne remote sensing measurements of greenhouse gases. Relevant satellite missions include the NASA OCO-2 mission; the GOSAT and the GOSAT-2 missions; ESA Sentinel 5-P; TanSat mission; MicroCarb by CNES; the Copernicus Carbon Dioxide Monitoring mission CO2M; ESA Sentinel 5; MERLIN, a joint mission by DLR and CNES and other missions. Here we present long-term measurements of greenhouse gases at Sodankylä and comparisons with satellite borne observations. High-resolution Fourier Transform infrared spectrometer has been operational in Sodankylä since early 2009. The most recent data version is based on the TCCON GGG2020 retrieval. At the Sodankylä TCCON site we have also performed balloon borne observations of greenhouse gases using AirCore technique. The AirCore observations are directly related to the World Meteorological Organization in situ trace gas measurement scales. Therefore, AirCore observations can be used for calibration of the remote sensing observations.


315 Simple annual CO2 flux indicator from Sentinel-2 and ERA5 data

Poster

Ludovic Arnaud*, Ainhoa Ihasusta, Ahmad Al Bitar, Remy Fieuzal, Taeken Wijmer, Eric Ceschia

CESBIO, Université de Toulouse, CNES/CNRS/INRAE/IRD/UT3, Toulouse, France

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

   In recent projects [1,2], our team has been in charge of developing an indicator that evaluates the annual CO2 flux of agricultural parcels.  The development of this indicator focussed on the scientific methodology, the algorithms, the software designs and the output production as maps [1,2]. The indicator responds to the so-called "tier 1" terminology which mean that simplicity of usage and scalabilty is prefered to high accuracy. More precisly, the indicator is independant of the type of crop or region, relatively easy to implement at large scale, and has an uncertainty that is completly characterized.

   The methodology is based on the following observations [3]: at first approximation, the annual CO2 flux of a parcel seems correlated to the number of days it is covered by an active photosynthetic vegetation. The key point of the methodology is to estimate the vegetation covering from remote sensing. However, a precise in-situ validation of the method itself permormed on the agricultural ICOS sites, shows that the performances are not satisfying, even for a tier 1 approach.

   With the help of the agricultural ICOS sites flux database, and the inclusion of climatic variables, an improved methodology with better accuracy for the same level of complexity is proposed.

[1] https://www.niva4cap.eu/ (H2020 project)

[2] SOCCROP project (https://www.inrae.fr/actualites/soccrop-premier-indicateur-devolution-du-stockage-carbone-sols-agricoles)

[3] Ceschia et al. Agriculture Ecosystems & Environment 139(3):363-383 (2010)


316 Urban Atmospheric Monitoring Network Requirements to track CO2 Emissions until Climate Neutrality

Oral

Ivonne Albarus1,2*, Charbel Abdallah3, Hervé Utard2, Jinghui Lian1,2, Mali Chariot1, Philippe Ciais1, Olivier Laurent1, Michel Ramonet1, David Duccini2, Valerie Gros1, Thomas Lauvaux3,1

1LSCE, Paris, France. 2Origins.earth, Paris, France. 3GSMA, Reims, France

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Cities, accounting for over 70% of global greenhouse gas (GHG) emissions and generating more than 80% of global income, are actively enacting mitigation policies to drive climate action. Therefore, understanding in detail the spatiotemporal distribution of total urban GHG emissions is crucial for effective emission reduction strategies. This study assesses the effectiveness of urban atmospheric monitoring networks in tracking carbon dioxide (CO2) emissions within the Paris metropolitan area in line with its climate action plan. Using a high-resolution dynamic emissions inventory and atmospheric modeling, we assess signal-to-noise ratios (SNR) of fossil fuel CO2 concentrations to evaluate emissions detectability and the potential lifetime of our observation network as carbon emissions decrease. The network comprises different sensor types, including high-precision and medium-precision CO2 sensors, offering a cost-effective option for densifying existing networks and providing comprehensive coverage.

Our findings reveal decreasing SNR trends and CO2 concentration detectability (signal) until 2035-2040 for various sensor types, influenced by model errors, background concentrations, and measurement uncertainties (noise). Emission detection is influenced by both seasonal variability and spatial concentration variances. Wintertime is suitable for tracking long-term emissions trends, while significant concentration gradients exist from urban to rural areas. Adjusting the spatial coverage accordingly ensures sustained network effectiveness over time. This research highlights challenges and opportunities in urban GHG monitoring, advocating for multifaceted approaches integrating observational, experimental, and modeling methods. By illustrating emission dynamics and uncertainties, our findings support climate policies and advance emissions reduction strategies in urban environments.


317 Understanding the effects of alternative cutting methods on water and light use efficiency of a peatland forest

Oral

Zifan Guo1,2*, Xuefei Li1, Mika Korkiakoski1,3, Paulina Dukat1, Yann Salmin1, Timo Vesala1

1Institute for Atmospheric and Earth System Research/Physics (INAR), Helsinki, Finland. 2Beijing Forestry University, Beijing, China. 3Finnish Meteorological Institute, Helsinki, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

In Finland, there is an increasing trend towards harvesting forests  growing on drained peatlands. Understanding the mechanisms behind how ecosystem carbon (C) and water use efficiencies respond to harvesting is vital for evaluating the effects of management practices on ecosystem C and water cycles in boreal peatland forest ecosystems. However, as different harvesting practices, how partial cutting vs. clear-cutting affect ecosystem water use efficiency (WUE), light use efficiency (LUE), and the C budget as well as how it develops during the years following the cutting of a boreal nutrient-rich peatland forest remain uncertain. Over 6 years before and after harvest, continuous CO2 and H2O fluxes were measured with the eddy covariance method before and after cutting in a mature, nutrient-rich peatland forest in southern Finland. Both partial and clear-cutting significantly decreased the ecosystem WUE and LUE, and clear-cutting decreased more than partial cutting. Furthermore, the sensitivity of WUE and LUE to radiation and vapor pressure deficit (VPD) was sequentially reduced corresponding to pre-cutting, partial cutting and clear cutting. As the forest stand developed, there was a gradual increase in both WUE and LUE, attributable to the enhanced forest biomass. Notably, high summertime air temperature (Ta) and VPD were observed to limit net ecosystem production. These results improve our understanding and predictive capabilities regarding the changes in WUE, LUE and C balance in boreal peatland forest subjected to harvesting. These insights provide a robust scientific foundation for assessing ecosystem stability in boreal peatland forest.


318 Advancing Urban Greenhouse Gas Monitoring: Development and Evaluation of a High-Density CO2 Sensor Network in Munich

Oral

Patrick Aigner1*, Daniel Kühbacher1, Adrian Wenzel1, Adrian Schmitt1, Felix Böhm1, Moritz Makowski1, Klaus Kürzinger1, Olivier Laurent2, Pascal Rubli3, Stuart Grange3, Lukas Emmenegger3, Jia Chen1

1Technical University of Munich (TUM), Munich, Germany. 2Laboratoire des Science du Climat et de l’Environnement (LSCE/IPSL), Gif-sur-Yvette, France. 3Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, Switzerland

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Cities are a focus of the European Union’s effort to become climate-neutral by 2050. The ICOS Cities project aims to create services for cities to assist and quantify their pursuit of gradually reducing emissions over the following decades. An essential input for this is quality-controlled atmospheric measurement data from trusted sources. In three pilot cities, Paris, Munich, and Zurich, different sensor networks were set up with varying sensor accuracy,  network density, and location characteristics.

Here, we present an overview of Munich’s mid-cost sensor network ACROPOLIS: Autonomous and Calibrated Rooftop Observatory for MetroPOLItan Sensing. The network comprises 20 sensor systems on rooftops in and around the city with a targeted CO2 measurement accuracy of 1ppm. In addition, we aim to reduce operating costs and effort by automating procedures and designing the systems as permanently connected Internet of Things (IoT) devices. Hardware and software development was carried out in-house, featuring a temperature-controlled outdoor enclosure, an automated sensor system, two calibration cylinders, and an external unit with a wind sensor and air inlet. Every sensor node uses a Vaisala GMP343 CO2 Sensor (NDIR) complemented by auxiliary humidity, pressure, and temperature sensors. 

We demonstrate our operation and calibration strategy to achieve the targeted performance and assess sensor performance primarily through Root Mean Square Error (RMSE), obtained during a multiweek outdoor side-by-side campaign with a Picarro G2301. Additionally, we will discuss sensor placement and share preliminary results from 6 months of observations in Munich.


319 ICOS Carbon Portal: Services and User Experience

Poster

Ute Karstens1,2*, Claudio D'Onofrio1,2, Margareta Hellström1,2, Liisa Ikonen3, Harry Lankreijer1,2, Oleg Mirzov1,2, Ida Storm1,2,4, Angeliki Adamaki1,2, André Bjärby1,2, Klara Broman1,2, Anders Dahlner1,2, Remco de Kok4, Arndt Meier1,2, Jonathan Schenck1,2, Jonathan Thiry1,2, Zhendong Wu1,2, Zois Zogopoulos1,2, Alex Vermeulen2,1

1Lund University, Physical Geography and Ecosystem Sciences, Lund, Sweden. 2ICOS ERIC, Carbon Portal, Lund, Sweden. 3ICOS ERIC, Head Office, Helsinki, Finland. 4Wageningen University and Research, Wageningen, Netherlands

Session 16. Continuous Learning in a changing world - Teaching and learning novel tools & methods used for measurement techniques’, data & policy

ICOS Carbon Portal is the data centre of the ICOS Research Infrastructure and responsible for long-term storage and dissemination all ICOS and ICOS-related data. Beyond archiving, it offers support for working with and analysing ICOS data. A diverse set of services is provided, ranging from the data discovery through a versatile search interface to models supporting the interpretation of the measurements. It also provides a virtual research environment that provides easy access to analysis tools. Recognizing the importance of user input, we take the opportunity of the ICOS Science Conference to ask the ICOS community and all users to help us to further improve and expand our services.

On this poster, we briefly introduce all our services, provide links to more detailed service documentation and invite conference participants to give us feedback on existing services, to suggest ideas for future developments or to engage in user feedback groups.


320 Use of a Lagrangian transport model for atmospheric inversions using satellite observations: case study using TROPOMI to estimate CH4 emissions over Europe

Oral

Rona Thompson*, Ignacio Pisso, Philipp Schneider, Kerstin Stebel, Nalini Krishnankutty, Stephen Platt

NILU, Kjeller, Norway

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

We present a novel and computationally efficient method for atmospheric inversions of satellite observations using a Lagrangian Particle Dispersion Model (LPDM) and demonstrate its use over Europe. LPDMs have several advantages over Eulerian models. First, they can more precisely represent an observation since calculations are independent of a computational grid and second, LPDMs can be run in a backwards in time mode, which allows the computation of the sensitivity of an observation to fluxes and in this way are sometimes said to be “self adjoint”. The LPDM used in our study is FLEXPART. 

In our method, FLEXPART is run in a backwards-in-time mode to determine total column source-receptor relationships (SRRs), which describe the relationship between a total column observation (such as from a satellite) and fluxes. The SRRs are used in the Bayesian inversion framework, FLEXINVERT, to optimize fluxes over a nested domain. Background mixing ratios for the total column observations are determined by coupling FLEXPART backward trajectories with the outputs of the CAMS data assimilation product, EGG4. 

Using FLEXPART-FLEXINVERT, we determine CH4 emissions over Europe using observations from the TROPOspheric Monitoring Instrument (TROPOMI) onboard Sentinel 5P. We compare results using the Official retrieval product versus the research project, WFMD, from the University of Bremen, and against results using observations from the ICOS network.


322 Emission Inventory for Human Respiration: Case Study in Munich Utilizing Statistical and Mobile Network Data Methods

Oral

Julian Hinderer1*, Patrick Aigner1, Daniel Kühbacher1, Beyza Yirtar1, Enrichetta Fasano2, Bradley Matthews2, Jia Chen1

1Technical University of Munich (TUM), Munich, Germany. 2University of Natural Resources and Life Sciences, Vienna, Austria

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

In the pursuit of comprehensive carbon dioxide (CO2) emission inventories, understanding the contribution of human respiration is essential. This holistic view is required to bridge the gap between modeled and observed emissions, thereby facilitating more targeted climate action strategies. Consequently, alongside ongoing inventory efforts in Munich across various sectors such as public power, heating, and traffic, a novel inventory focusing on human respiration emissions has been developed. The inventory offers spatial resolution at 100 m x 100 m and time profiles with hourly intervals. Two distinct methodologies are compared: (1) a statistical approach utilizing datasets such as population demographics, land use, and time use surveys, supplemented by data sources like Google reviews, and (2) a mobile network data approach, which tracks individuals based on their mobile device signals received by nearby mobile towers. The mobile network data, pre-processed by the vendor, offer a spatial resolution depending on mobile cell density and privacy considerations. To achieve the desired finer grid resolution, downscaling is necessary. For the temporal perspective, hourly tracking of individuals in each cell unveils previously unexplored patterns. Through the analysis of results yielded by the two methodologies, the aim is to discern spatial and temporal disparities between them, identify their respective strengths and weaknesses, and propose enhancements for the more cost-effective statistical approach, leveraging insights obtained from the mobile network approach. By tailoring these methodologies to Munich's unique characteristics, a groundwork can be laid for emission inventories in other urban settings as well.


323 Carbon dioxide and methane fluxes over the coastal Baltic Sea

Poster

Vähä Aki1,2*, Nicolas-Xavier Geilfus2, Pasi Kolari1, Alf Norkko2, Joanna Norkko2, Kurt Spence2, Ivan Mammarella1

1Institute of Atmospheric and Earth System Research, University of Helsinki, Helsinki, Finland. 2Tvärminne Zoological Station, University of Helsinki, Hanko, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

The fate of carbon in the coastal sea is emerging as a vital component in the global carbon cycle. In a healthy state, the coastal sea acts as a carbon sink, but a degraded state could potentially turn the coastal sea to a source of carbon in the form of emitted carbon dioxide (CO2) and methane (CH4). However, the carbon budget in the coastal sea is often poorly constrained due to an inadequate amount of available data. The new ICOS Associated ecosystem site FI-Tvm commenced its operation in 2022. The station is situated in the coastal Baltic Sea by the Tvärminne Zoological Station and enables a better-constrained carbon budget in the coastal sea.

We report here the measured sea–atmosphere CO2 fluxes between April 2022 and March 2024. The measured mean monthly CO2 fluxes varied between −0.3 ± 0.4 µmol m−2 s−1 (± STD, net sink) and 0.4 ± 0.3 µmol m−2 s−1 (net source). The CO2 fluxes were relatively small but most of the monthly means differed significantly (p < 0.05) from 0. There was a significant (p < 0.05) difference in the day- and night-time CO2 fluxes from March to October, likely reflecting diurnal changes in environmental drivers. CH4 fluxes were measured during late 2023 and early 2024. The magnitude of these fluxes was 10 ± 40 nmol m−2 s−1. Further analysis will concentrate on better distinguishing the terrestrial influence from the sea–air fluxes, determining which environmental parameters are driving the fluxes, and flux gapfilling.
 

324 Methane sources in Cluj-Napoca, Romania: insights from isotopic analysis

Oral

Jacoline van Es1*, Carina van der Veen1, Calin baciu2, Mustafa hmoudah2, Thomas Rockmann1

1Utrecht university, Utrecht, Netherlands. 2Babes Bolyai Univeristy, Cluj-Napoca, Romania

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Methane (CH4) is a more potent greenhouse gas with a shorter lifetime than CO2. Reduction of methane emission is necessary to mitigate climate change on short time scales. Mitigation of methane emissions requires a solid understanding of the location, strength, and source of emissions. The source can be identified by the isotopologues because different sources emit CHwith a different isotopic composition. These isotopologues can be measured via an isotope ratio mass spectrometer (IRMS). Utrecht University operates an IRMS system that can measure δ13C and δD of CH4. This system can be deployed at the station to measure the isotopologues at high precision with a 20-min resolution. This system is, as part of the new Horizon Europe project PARIS (Process Attribution of Regional Emissions), deployed in Cluj-Napoca. This campaign expands the coverage of high-time resolution CHisotopic measurements in Europe. The goal is to investigate the typical source mix of methane in various regions and investigate whether these observations agree with emission inventories. The time-series of Cluj-Napoca indicated that the nighttime accumulation was the most persistent factor for the rise in methane mole fraction and the δD and δ13C. When these enhancements were evaluated, two source mixtures were observed. The main source mixture was between the gas network and a river, and the second mixture was between the gas network and a fossil source. Furthermore, it suggests that the biggest enhancements come from the city centre which contains several sources that were investigated during a mobile survey.


325 Discrepancies between ICOS measurements and modelled greenhouse gas concentrations characterizing the parametrization error for greenhouse gas emission verification 

Poster

Diego Jiménez-de-la-Cuesta*, Beatrice Ellerhoff, Buhalqem Mamtimin, Andrea Kaiser-Weiss

Deutscher Wetterdienst, Offenbach am Main, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

One of the challenges of weather and climate numerical modelling is the parametrization of processes, for instance, convection and turbulence on scales smaller than the horizontal and vertical grid resolution. The parameterizations' simplifying assumptions lead, among others, to model errors. These model errors need to be characterized when performing emission estimation based on observed atmospheric concentrations (top-down emission estimation).

The integrated greenhouse gas emission verification project Integriertes Treibhausgas-Monitoringsystem (ITMS) for Germany aims to close the gap between bottom-up and top-down greenhouse gas (GHG) emission estimates. We use the numerical weather prediction model ICON (ICOsahedral Non-hydrostatic)-ART (Aerosols and Reactive Trace gases) to model the GHGs as tracers. We consider a limited-area domain that encloses Europe and use a 6.5-km-resolution grid. We compare ICOS measurements against corresponding model equivalents. We statistically analyze the differences in the observed and modelled methane concentration together with the differences in observed and modelled temperature and humidity, with emphasis on the vertical scale of the first few hundred meters near the ground: where the bulk of emissions, as well as the observations, take place.

This way, we identify the magnitude of errors of the parameterized processes, which, adequately considered, can subsequently improve the greenhouse gas emission verification.


326 Exploring the Use of Forest Inventory Data in an Inverse Modelling System for Monitoring the European Carbon Cycle

Oral

Marnix van de Sande1*, Gert-Jan Nabuurs1,2, Mart-Jan Schelhaas2, Auke van der Woude1, Joram Hooghiem1, Sara Filipek2, Ajdin Starcevic2, Pieter Zuidema1, Wouter Peters1,3

1Wageningen University, Wageningen, Netherlands. 2Wageningen Environmental Research, Wageningen, Netherlands. 3University of Groningen, Groningen, Netherlands

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Forests play a crucial role in the European Union’s mission to achieve net carbon neutrality by 2050. Accurate monitoring of forest CO2 sequestration is essential for policy support, and new methods are actively developed as part of the Copernicus CO2 monitoring and verification support (MVS) system. Inverse modelling, based on observations of atmospheric CO2, forms a key element in such a system. CO₂ inversions can capture short-term variability in surface CO₂ fluxes, such as during droughts. However, due to rapid mixing of atmospheric CO2, these modelling systems need additional information from local observations to be accurate across space. National forest inventories (NFIs) provide a promising observation stream of patterns of aboveground biomass, biomass increments, and forest age across space.

We introduce a framework to use information from NFIs as potential additional constraint in an inverse modelling system of the European carbon cycle. Our approach combines available forest inventory data with the forest resource simulation model EFISCEN-Space. We present an inventory-based map of forest biomass change in Europe, and show its application in an atmospheric modelling system of the carbon cycle. In addition, we compare our inventory-based map to some existing spatial data products of forest biomass change in Europe. In the near future, we focus on implementing this observation stream of European forests as additional constraint in CarbonTracker Europe, an existing inverse modelling system for the carbon cycle.


327 Measurements of CO2 fluxes over the Baltic Sea from land and ship using EC method and different gas transfer velocity parameterizations.

Oral

Iwona Niedzwiecka1*, Violetta Drozdowska1, Malgorzata Kitowska1, Karol Kulinski1, Przemyslaw Makuch1, Tomasz Neumann2, Jacek Piskozub1, Anna Rutgersson3

1Institute of Oceanology Polish Academy of Sciences, Sopot, Poland. 2Gdansk University of Technology, Faculty of Electronics, Gdansk, Poland. 3Uppsala Universitet, Department of Earth Sciences, Uppsala, Sweden

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

With the growing challenges of climate change, accurate estimates of air-sea CO2 fluxes are becoming critical. To calculate CO2 exchange rates and efficiencies and compare them with data from EC tower at Östergarnsholm Island, as well as with CO2 flux estimates from available parameterizations to calculate the gas transfer coefficient, we are using data on pCOconcentrations in water and atmosphere, wind speed, and surface organic matter in the Baltic Sea (BS) obtained from a research vessel. The goal of the research is to study gas exchange at the regional scale of the BS and in detail to determine the effect of surface organic matter on the gas transfer coefficient, which are crucial to the global carbon balance. Our study focuses on the unique conditions of the BS, including periodicity of strong winds, which allow for the examination of CO2 flux dynamics under extreme weather conditions. By comparing direct shipboard measurements with tower data and indirect methods, we aim to verify and potentially optimize existing models. Our work contributes to the expanding understanding of biogeochemical processes in the BS and their significance for the global carbon balance. The implications of our findings extend to climate change modeling and environmental policy, highlighting the critical role of diverse measurement and modeling approaches in offering a holistic view of CO2flux dynamics. Such comprehensive insights are vital for accurately predicting and effectively managing climate change impacts at both global and regional levels.


328 Impact of extreme drought events on soil carbon dynamics in mountains : experimental and observational study

Oral

Didier Voisin1*, Nicolas Bonfenti2, Margot Coisnon1, Chloé Colliat3, Florette Ecochard4, Guillaume Chagnaud1, Alix Reverdy1, Philippe Choler4, Jean-Christophe Clément2, Jean-Martial Cohard1, Jerome Foret5, David Gateuille3, Jerome Poulenard3, Jeremy Puissant4

1Université Grenoble Alpes, CNRS, IRD, G-INP, IGE, Grenoble, France. 2Université Savoie Mont Blanc, INRAE, CARRTEL, Thonon-les-Bains, France. 3EDyTeM, CNRS, Université Savoie Mont Blanc, Chambéry, France. 4Université Grenoble Alpes, CNRS, LECA, Grenoble, France. 5Université Grenoble Alpes, CNRS, Lautaret, Grenoble, France

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

Extreme weather events, such as droughts, are increasingly affecting mountainous regions, where soil drought is worsened by factors like reduced winter snowpack, as seen in the French Alps in 2022. These changes, coupled with intense summer rains, pose significant uncertainties for soil organic carbon dynamics in mountain soils.

To address this, we combined field observations, mesocosm experiments, and modelling approaches to investigate how drought and rain intensity affect carbon dynamics in mountain grassland.

In 2023, a short-term mesocosm experiment (4 months) was conducted, simulating a centennial drought and including two episodes of heavy rain events. Soil cores were sampled from a well-equipped mountain catchment at the Col du Lautaret, from two dominant grasslands. The cores underwent drought or control treatments in a paired design (16 mesocosms).

At the plot scale, we monitored CO2 fluxes (net ecosystem exchange, and carbon vertical leaching); changes in microbial community composition (via DNA amplicon sequencing); and extracellular enzyme activities.

At the catchment scale, carbon fluxes were monitored through continuous measures of net ecosystem exchange (ICOS FR-Clt flux tower) as well as through the collection of dissolved and particulate carbon samples after summer storms. Finally, a ParFlow-CLM hydrological simulation was set up for the catchment to evaluate the spatial variability of soil responses to drying-rewetting cycles analogous to those experienced in the mesocosm experiment.

With this integrated and interdisciplinary approach, we provide new insights into how extreme weather events shape the dynamics of soil organic carbon in mountain regions facing rapid climate warming.

 

329 VOC fluxes and concentrations at a boreal forest site before, during and after clear-cutting

Oral

Janne Rinne1*, Ross Petersen2, Cheng Wu3,4, Thomas Holst2, Erica Jaakkola2, Meelis Mölder2, Natascha Kljun2, Claudia Mohr5,6

1Natural Resources Institute Finland, Helsinki, Finland. 2Lund University, Lund, Sweden. 3Gothenburg University, Gothenburg, Sweden. 4Stockholm University, Stockholm, Sweden. 5Paul Scherrer Institute, Villigen, Switzerland. 6ETH Zurich, Zurich, Switzerland

Session 2. Exchange of reactive gases and aerosols between the land surface and the atmosphere in natural and managed ecosystems

Vegetation is the major source of volatile organic compounds (VOCs) into the atmosphere, where these compounds have both air quality and climate effects. However, data sets on ecosystem-level biogenic VOC emissions are very limited, both spatially and temporally, and our understanding e.g. of the effects of disturbances on VOC emissions from vegetation is rudimentary. As clear-cutting is the most common harvesting method in European boreal forest, understanding its effects on BVOC emissions is an important part of understanding the climate effects of forestry.

To provide data on ecosystem-level VOC emissions, and to quantify the effect of disturbance by forestry operations, we have measured ecosystem-level VOC emissions from a boreal coniferous ecosystem before, during and after the clear-cutting by eddy-covariance method with a VOCUS PTR-ToF-MS analyzer. In addition, we have used a gradient-flux approach with GC-MS sample analysis to speciate the emitted monoterpene species. The vertical VOC source-sink distribution within the forest canopy was also determined using the vertical profile of VOC concentration and Lagrangian dispersion method. 

The results indicate a large variety of VOC compounds being emitted by the forest system. These include terpenoids (isoprene, monoterpenes and sesquiterpenes). The most common monoterpenes emitted were α-pinene and Δ3-carene. The monoterpene emissions originated in summertime mostly from the canopy, with larger contribution from below-canopy emissions during spring and autumn. The forestry operations clearly increased the emissions of certain VOC emissions, e.g. monoterpenes by an order of magnitude, persisting several months following operations, while others were unaffected, e.g. isoprene. 


330 Mapping of Greenhouse gases within the Greater Athens Area using mobile measurements

Poster

Aikaterini Bougiatioti1*, Georgios Grivas1, Charalampos Chatzidiakos1, Eleni Liakakou1, Clement Narbaud2, Marc Delmotte2, Michel Ramonet2, Nikolaos Mihalopoulos1

1IERSD, National Observatory of Athens, Athens, Greece. 2LSCE, CEA, Université Paris-Saclay, Gif-sur-Yvette, France

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Greece is a EU country in the Eastern Mediterranean aiming to comply with recommendations for decreasing GHGs emissions. Furthermore, Greece has joined the Global Methane Pledge (GMP) in order to take voluntary actions and contribute to a collective effort to reduce global methane emissions at least 30% from 2020 levels by 2030.  It is well established that the primary sources of CO2 are fossil fuel combustion and industry while the ones of CH4 are emissions from fossil fuel use, agriculture and waste management, wetlands and other natural emissions.

In view of the above, since 2019 an ICOS-compliant cavity ring-down spectrometer (Picarro G2401) has been operating continuously at the Athens NOA urban background site. The equipment is calibrated according to the WMO-X2007 and WMO-X2004A reference scales for CO2 and CH4, respectively. Since fossil fuel combustion and waste management is an important source of both GHGs, specific routes were designed for mapping campaigns within Athens, to include major traffic arteries as well a sanitary landfill area, in order to characterize GHG levels within the GAA. The same routes were followed on a monthly but also weekly basis. Measurements were then compared to the urban background values, where a large burden is observed throughout the perimeter area of the landfill, which in places is two or three orders of magnitude above the background level. An increase in Δ-CO2 values is also observed in major traffic arteries and at the entrance of the facilities and is possibility associated with the presence of waste vehicles. 


331 Looking beyond our Eddy-Covariance backyard – vertical profiles at ecosystem stations

Poster

Alexander Graf1*, Lediane Marcon1, Marius Schmidt1, Dagmar Kubistin2, Matthias Lindauer2, Jennifer Müller-Williams2, Patrizia Ney3, Anne Klosterhalfen4, Christian Brümmer5, Jordi Vila6, Matthias Peichl7, Harry Vereecken1

1Forschungszentrum Jülich, Institute of Bio- and Geosciences: Agrosphere (IBG-3), Jülich, Germany. 2Deutscher Wetterdienst, Meteorological Observatory Hohenpeissenberg, Hohenpeissenberg, Germany. 3Forschungszentrum Jülich, Dept. of Safety and Radiation Protection, Environmental monitoring: Meteorology (S-UM), Jülich, Germany. 4University of Göttingen, Bioclimatology, Göttingen, Germany. 5Johann Heinrich von Thünen-Institut (TI), Bundesforschungsinstitut für Ländliche Räume, Wald und Fischerei, Institut für Agrarklimaschutz, Braunschweig, Germany. 6Wageningen University and Research – Meteorology and Air Quality, Wageningen, Netherlands. 7Swedish University of Agricultural Sciences, Department of Forest Ecology and Management, Umeå, Sweden

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

The well-equipped eddy-covariance (EC) stations of the ICOS ecosystem network are ideal testbeds for tentatively measuring or estimating additional variables relevant to monitoring or modelling global change. A common limitation of a standard EC station is the confinement of most variables to the EC measurement height, which is typically limited by factors such as footprint size, the need to avoid the roughness sublayer, and tower construction costs. Few (mostly forest) stations provide some measurements below this height, and almost none offer measurements above it. Here, we present past and ongoing efforts to close these gaps.

For scalars and wind below the EC height, we developed a profiling system, that mitigates calibration issues and sensor costs by moving sensors and tubes within crop canopies and their roughness sublayer. The original system for CO2, H2O, wind and temperature, which moves up and down continuously at one location, is currently being replaced by a robot-arm based system to enhance flexibility in movement speed and horizontal measurement locations.

For scalars above the EC height, we demonstrated in previous research that the potential temperature of the well-mixed part of the convective planetary boundary layer can be estimated from turbulence data measured by the EC equipment. We present first steps to extend this approach to CO2. Ultimately, we aim at testing the feasibility of this and other ‘virtual tall tower’ concepts for infrastructures such as ICOS. In case of a positive evaluation, spatial data density could be dramatically increased helping to verify atmospheric inverse modelling estimates.

 

332 Novel belowground in-situ gas labelling approach for methane production and oxidation: case study at a boreal peatland

Poster

Xuefei Li1*, Lukas Kohl2, Klaus-Holger Knorr3, Maxim Dorodnikov3

1Institute for Atmospheric and Earth System Research/Physics, University of Helsinki, Helsinki, Finland. 2School of Forest Sciences, University of Eastern Finland, Kuopio, Finland. 3Institute for Landscape Ecology, University of Münster, Münster, Germany

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Previous studies on methane (CH4) dynamics in peatlands relied on laboratory incubations, which inevitably disrupt natural conditions and potentially skew rate estimates. To address this, we developed a novel in-situ gas labelling approach using passive diffusion chambers (PDC) to deliver 13C-acetate, 13C-CO2 and 13C-CH4 into the peat, enabling the determination of in-situ potentials for acetoclastic methanogenesis (PAM), hydrogenotrophic methanogenesis (PHM) and CH4 oxidation (PMO). 

In December 2020, we deployed 24 PDCs at depths of -30 and -50cm in Siikaneva fen, southern Finland. We conducted 11-day in-situ labelling compaigns in two consecutive summers. Background (non-labeled) δ13C-CH4 averaged -75.9‰ (30cm) and -78.9‰ (50cm), and δ 13C-CO2 averaged -5.4‰ (30cm) and -1.9‰ (50cm). All end product values substantially increased after label injection, indicating successful implementation. 

In-situ PAM, PHM and PMO showed no significant differences between the depths, with PAM being 2.0 nmol L-1 h-1, PHM being 0.51 nmol L-1 h-1 and PMO being 20 nmol L-1 h-1 at both depths. We conducted also in-vitro incubation in a similar way as in-situ measurement. In-vitro PAM was estimated at 3.6 (30cm) and 0.4 (50cm) nmol L-1 h-1 and In-vitro PHM was estimated at 1.6 (30cm) and 2.50 (50cm) nmol L-1 h-1In-vitro PMO showed higher rates than in-situ results, averaging at 253 (30cm) and 34 (50cm) nmol L-1 h-1

Additionally, we optimized a CH4 process model using Trust Region Reflective algorithm incorporating both in-situ and in-vitro data. Further details and discussion will be presented during the session.

 

333 Linking extreme ENSO years to the Global Methane Budget

Oral

Bibhasvata Dasgupta*, Thomas Roeckmann

Utrecht University, Utrecht, Netherlands

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

ENSO has a limited impact on the variability and growth rate of atmospheric methane and its isotope, with only up to 36% of the variability in methane levels attributable to ENSO, particularly in the southern tropics (Schaefer et al., 2018). However, ENSO-influenced drought can drive methane flux dynamics in tropical wet forest soil, with drier conditions increasing soil methane consumption from the atmosphere (Aronson et al., 2019). ENSO also influences wetland methane interannual variability, with repeated El Niño events contributing to reduced methane emissions and stabilized atmospheric concentrations (Hodson et al., 2011). The impact of ENSO on the interannual variability of methane is a function of both source and sink processes. While stronger ENSO events have recorded notable increases in methane emissions from wetlands, long-term ENSO signal also shows a significant correlation with tropospheric hydroxyl radical and ozone levels, and is largely driven by natural variations in global emissions and meteorology, with changes in fire emissions and meteorology associated with El Niño having opposing impacts on tropospheric ozone burden. Towards this, we isolate the interannual and seasonal effect of ENSO bimonthly MEI on the atmospheric background methane levels measured from high latitude measurements of methane mole fraction and isotope composition. This allows us to deconvolve the methane budget between sources and sinks in the years of strong ENSO activity and link ENSO-governed climatic drivers to interannual methane variability.

 

334 Studying atmospheric greenhouse gas variability through synthetic satellite data generated by the DEHM model.

Poster

Niels S. Hvidberg1*, Anne Sofie Lansø1, Jesper Heile Christensen1, Hoyeon Shi2, Jacob Høyer2, Camilla Geels1

1Aarhus University, Roskilde, Denmark. 2Danish Meteorological Institute, Copenhagen, Denmark

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

Effectively monitoring atmospheric CO2 concentrations plays a crucial role in implementing new policies that target reductions in emissions on national basis as well as the taxation for violating these agreements. In 2026 the first of a new group of three satellites is planned to be launched as part of the Copernicus Anthropogenic Carbon Dioxide Monitoring (CO2M) mission. The new satellites will carry equipment capable of detecting anthropogenic CO2 signals at country or megacity scales.

Several recent studies have investigated the possibilities and precision of the CO2M satellites and made comparisons to current CO2 measuring satellites such as the Orbiting Carbon Observatory-2 (OCO-2). The CO2M mission will have higher resolution and a much wider swath, increasing from 10.3 km to 250 km.

This study focuses on modeling atmospheric CO2 concentrations with the combined atmosphere-biosphere model of DEHM (Danish Eulerian Hemispheric Model) and SPA (Surface Plant and Atmosphere) around Copenhagen, Denmark, with the possibility to expand to other countries in Europe. The output data from DEHM will then be used to generate synthetic satellite images, that follows a setup resembling the upcoming CO2M satellites. The goal is to investigate the satellites detectability of variations in CO2 concentrations in the atmosphere around Copenhagen.

The ongoing work of further developing the combined DEHM-SPA model setup will pe presented together with the current analysis of CO2 variability and surface-to-column propagation within the atmosphere. Additionally, preliminary results for the synthetic satellite data will be presented and discussed.

 

335 Continuous ∆CO-based ∆ffCO2 record of the ICOS network: signal strength and uncertainties

Poster

Maksym Gachkivskyi1,2*, Fabian Maier1,3, Julian Della Coletta2, Susanne Preunkert2, Xochilt Gutierrez4, Armin Jordan4, Tobias Biermann5, Sebastien Conil6, Arnoud Frumau7, Tobias Kneuer8, Dagmar Kubistin8, Irene Lehner5, Matthias Lindauer8, Morgan Lopez9, Jennifer Mueller-Williams8, Martin Steinbacher10, Samuel Hammer2

1Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany. 2ICOS Central Radiocarbon Laboratory, Heidelberg University, Heidelberg, Germany. 3Max Planck Institute for Biogeochemistry, Jena, Germany. 4Max Planck Institute for Biogeochemistry, ICOS Flask and Calibration Laboratory, Jena, Germany. 5Centre for Environmental and Climate Science, Lund University, Lund, Sweden. 6DISTEC/EES, Andra, France. 7TNO, Environmental Modelling, Sensing & Analysis, Petten, Netherlands. 8Deutscher Wetterdienst - Meteorological Observatory Hohenpeissenberg, Hohenpeißenberg, Germany. 9LSCE, IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France. 10Empa, Laboratory for Air Pollution / Environmental Technology, Dübendorf, Switzerland

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Estimating fossil fuel CO2 enhancement (∆ffCO2) at measurement sites often relies on the well-established technique of comparing 14C  depletion between the site and a “clean” background station. However, this approach has been limited by the absence of sufficiently precise continuous 14C observation techniques. Up-to-date, only sparse 14CO2 grab sampling  is performed. Recently Maier et al. (2023) have shown that readily available co-emitted proxies, such as carbon monoxide (CO), can serve as surrogate tracers for ffCO2 providing continuous ∆ffCO2 estimates. While CO-based ∆ffCO2 assessments have primarily focused on urban areas with high fossil fuel signals, this study extends the CO-based ∆ffCO2 concept to the European scale. 

We use the Integrated Carbon Observation System (ICOS) station in Mace Head (MHD), Ireland, as background reference for the European ICOS network. By combining high-precision 14C-based ∆ffCO2 estimates with concurrently observed ∆CO excess, station-specific ∆CO/∆ffCO2 ratios are assessed. Continuous hourly CO-based ∆ffCO2 estimates can be retrieved by combining the continuous ∆CO excess records and the station-specific 14C-based ∆CO/∆ffCO2 ratios. Our analysis also investigates spatial gradients in the ∆CO/∆ffCO2 ratio across Europe and compares these with expected changes derived from bottom-up emission inventories. Finally, we analyse the average ∆CO-based ∆ffCO2 signals at ICOS sites and discuss these results in the context of their uncertainties.


336 The ICOS background station at Plateau Rosa and the assessment of high-resolution CH4 simulations in complex terrain

Poster

Giulia Zazzeri1*, Francesco Apadula1, Andrea Lanza1, Stephan Henne2

1Ricerca sul Sistema Energetico - RSE SpA, Milano, Italy. 2EMPA, Dübendorf, Switzerland

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

In this study we analyse the methane mole fractions measured at the atmospheric station at Plateau Rosa since 2018 with a Picarro cavity ring down spectrometer G2301. The station, at 3480 meter MSL, represents an ideal location for, on one hand, measurements of background air and estimation of the global trend and, on the other hand, intercepting pollution events at regional scale. Since 2021 the site contributes as an atmospheric station to the ICOS network. 

We provide an analysis of the continuous record of CH4 since 2018 and pollution events observed at the station. We used the FLEXPART atmospheric transport model coupled to the high-resolution (1 km x 1 km) output of the numerical weather prediction model COSMO to simulate regional CH4 contributions. We assess how well the transport model coupled to different bottom-up inventories (EDGAR, TNO, Swiss national) can capture observed variability. We focused our analysis on April 2022, when the CH4 increment above the baseline was consistently high, and March 2024, where a CH4 enhancement of several days was observed.

We demonstrate how the CH4 mole fraction data measured continuously at the station at Plateau Rosa can be used to better understand CH4 emissions in Europe and how they compare to updated inventories. 

 

337 Assessing the permanence of ocean carbon sequestration in the North Atlantic with implications for marine carbon dioxide removal efficacy and verification

Poster

Chelsey Baker*, Adrian Martin, Andrew Yool, Ekaterina Popova

National Oceanography Centre, Southampton, United Kingdom

Session 8. Enhancing the ocean carbon sink: the science, verification, and governance of marine-based carbon dioxide removal (mCDR)

The North Atlantic Ocean is being explored as a region for deploying marine carbon dioxide removal biomass-sinking approaches. The quantity of biomass sunk from the surface, the region and depth at which it is remineralized, and the subsequent timescale of ventilation controls the magnitude and permanence of carbon sequestration. We apply Lagrangian tracking in two ocean circulation models of medium (1/4°; eddy-permitting) to high (1/12°; eddy-resolving) resolution to determine the fate of sinking biomass in the North Atlantic. Remineralized biomass at three vertical horizons (500, 1,000, and 2,000 m) is tracked to determine how much remains out of contact with the atmosphere for 100 years. The fraction that remains below the mixed layer for 100 years is defined here as the sequestration efficiency. At each of the 500, 1,000 and 2,000 m horizons, the sequestration efficiency is 28%, 66% and 94%, respectively for the medium-resolution model and decreases to 47.5% at 1000m for the high-resolution model, a ~19% discrepancy between different model resolutions. Calculating the amount of carbon sequestered using depths ≤1,000 m, whilst not accounting for downstream ventilation, overestimates carbon stored on 100-year timescales. This work has implications for the accuracy of more affordable and accessible methodologies to estimate the permanence of carbon storage using lower resolution models which dampen connectivity between different North Atlantic regions. Furthermore, the study highlights that the choice of location is critical for marine carbon dioxide removal deployments that require long-term sequestration in the ocean interior to be successful.


338 How AERIS atmosphere Data Centre contributes to disseminate and promote greenhouse gases data

Poster

payan sébastien*

AERIS / DATA TERRA, Paris, France

Session 17. Best Practices in the landscape of Research Infrastructures: Cooperation, Co-location and other lessons learned

The AERIS atmosphere Data Centre (www.aeris-data.fr), part of the French Data Terra Research Infrastructure (https://www.data-terra.org), has the objective to facilitate and enhance the use of atmospheric data, whether from satellite, aircraft, balloon, or ground observations, or from laboratory experiments. To accelerate scientific research and support collaboration between French researchers and their international colleagues, AERIS develops and implements tools and services to facilitate the sharing and use of information and data, for example in the specific field of greenhouse gases (GHG). Indeed, AERIS collects, archives and disseminates data on greenhouse gases and other related gases (such as CO for example) in the atmosphere, observed in the framework of various programs or projects. It also contributes to the production of data when processing is necessary to go from raw data to calibrated data, for example. Satellite (IASI, GOSAT, MicroCarb, …), campaigns (MAGIC, DACCIWA, …), Aircraft (SAPHIR+, IAGOS) or Balloon (HEMERA), ground measurements (ICOS-FR, TCOON-Paris, ACTRIS),  Laboratory databases (GAISA, IUPAC, ECCAD), AERIS makes accessible a large set of original data, covering a wide range of geographical areas and time periods. AERIS is therefore used to provide and update greenhouse gas observation data provided by organizations or researchers offering today a vast archive of data enriched over time

This presentation of AERIS will then be focused on GHG data with a focus on tools and services implemented for related campaigns, cal/val activities, ground networks, and space mission retrieved products. Discussion on portal approach to cross use of different GHG data sets will be discussed.


339 Net Zero Carbon Berlin: Developing a Systems Framework

Poster

Christopher Ryan*, Galina Churkina

Technische Universität Berlin, Berlin, Germany

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Cities are increasingly being considered as important locations in relation to the specificities of their carbon (C) cycling. In addition to being sites of potential significant reductions in greenhouse gas (GHG) emissions, there is growing discourse related to cities as being places of C sequestration. As the largest city in Germany, Berlin plays a significant role in leading these endeavors. Various cities around the world have created plans for the long-term monitoring and quantification of such balances, and previous research in Berlin has similarly assessed both emissions and sequestration of GHGs, including quantifying C stocks such as in surface and subsurface soil, aboveground tree biomass, as well as sequestration potential related to construction approaches and materials. Similarly, C emission estimates for Berlin include processes related to solid waste and overall GHG emissions. The city of Berlin has a goal of achieving climate-neutrality by 2050 with on-going political agitation for moving this timeline forward. Such a transition requires a comprehensive systems approach that considers urban impacts beyond the geographical extent of municipal boundaries. This project draws from existing published data to develop a quantified schema for relevant flows and stocks of C within Berlin taking a comprehensive systems-wide perspective for achieving net zero C. This schema incorporates sectors such as energy, urban design, transportation, and industry, with practical application in the realms of biogeochemical modeling, urban planning, and policy, all of which benefit efforts in achieving goals related to climate neutrality in Berlin.


340 Comparison of CO2 Balances in Finnish Terrestrial Biosphere: Bottom-up vs. Top-down

Poster

Kielo Isomäki1*, Matthew McGrath2, Leif Backman1, Juha Leskinen1, Antoine Berchet2, Gregoire Broquet2, Audrey Fortems-Cheiney2, Virpi Junttila3, Antti Leppänen4,1, Hannakaisa Lindqvist1, Anteneh Mengistu1, Annikki Mäkelä4, Maarit Raivonen4, Laura Thölix1, Tuula Aalto1

1Finnish Meteorological Institute, Helsinki, Finland. 2Laboratoire des Sciences du Climat et de l’Environment (LSCE), Gif-sur-Yvette, France. 3Finnish Environment Institute, Helsinki, Finland. 4Institute for Atmospheric and Earth System Research (INAR), Helsinki, Finland

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Emissions and removals from the land use, land use change and forestry (LULUCF) sector hold significant importance to Finland's climate policy, emphasizing the need for precise tracking of carbon stock changes in the terrestrial biosphere. The reported emissions and removals from LULUCF sector in national greenhouse gas inventory (NGHGI) are subject to high uncertainty. In support of NGHGIs, independent top-down (TD) and bottom-up (BU) methods have been developed to quantify and verify CO2 fluxes from LULUCF and associated biospheric processes. 

Advancements in computation and observation methods have led to rapid progress in both BU and TD methods, with TD methods demonstrating significant potential. Rapid progress emphasizes the importance of analyzing newest available data together with its uncertainty ranges and of monitoring how methodological advancements affect the estimated total carbon balances. We consolidate existing research dataset covering large number of TD and BU estimates and contrast those against NGHGI of Finland to gain understanding of applicability of these methods in national context. 

According to the national greenhouse gas inventory, biosphere in Finland removed annually on average [uncertainty range] –4.6 [-7.6 … -1.6] Mt C (of CO2) between the years 2012 and 2020. We found consistency between TD, BU and NGHGI estimates, but large uncertainties found in BU and TD country-level balances (annual averages ranging from –49 to +32 Mt C) prohibit reliable verification of the inventory. The closest estimate was found from an ensemble of regional BU methods while the furthest estimate was provided by the regional high-resolution TD ensemble.


341 Understanding the climate impacts of rewetting in a boreal peatland forest

Poster

Ellinoora Ekman1*, Kari Minkkinen2, Anuliina Putkinen3,4, Olli-Pekka Siira1, Roosa Hautala2, Angelika Kübert1, Xuefei Li1, Paavo Ojanen2,5, Maarit Raivonen1, Erkka Rinne6, Annalea Lohila1,6

1Institute for Atmospheric and Earth System Research/Physics, University of Helsinki, Helsinki, Finland. 2Department of Forest Sciences, University of Helsinki, Helsinki, Finland. 3Institute for Atmospheric and Earth System Research / Forest Sciences, University of Helsinki, Helsinki, Finland. 4Environmental Soil Sciences, Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland. 5Natural Resources Institute Finland (Luke), Helsinki, Finland. 6Finnish Meteorological Institute, Helsinki, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Peatlands are huge carbon storages, but due to human activities, part of this carbon is released to the atmosphere intensifying global warming. In Finland, circa half of the peatland area is drained for forestry. Drainage, together with intensive harvesting, alters water table level (WTL), and further leads to soil CO2 emissions, especially in nutrient-rich sites. Rewetting causes CH4 emissions but eventually the soil becomes a carbon sink again, and the accumulation of carbon will exceed the warming effect of CH4 emissions. It is not yet fully understood how rewetting temporally affects ecosystem processes as well as carbon and greenhouse gas (GHG) balance in different peatland forest ecosystems. 

A forestry-drained peatland site in Tammela, Southern Finland, is currently being rewetted. With various measurements using the eddy covariance technique, closed chambers, soil incubation experiments, water table loggers and sap flow sensors we want to understand how rewetting affects GHG-fluxes both at the ecosystem and the soil level, the surface energy balance and tree water consumption. Most of the measurements started two years ago and will be ongoing several years after the rewetting. This study will produce new knowledge about the local and global climate impacts and about the hydrological effects of rewetting in peatland forest ecosystems. Here, we present the site and the measurement set-up with some preliminary results from the ecosystem GHG flux measurements and the incubation experiments before the rewetting.


342 An assessment of CO2 storage and sea-air fluxes for the Atlantic Ocean and Mediterranean Sea between 1985 and 2018.

Oral

Meike Becker1,2*, F. F. Perez3, N. Goris4,2, M. Gehlen5, M. Lopez-Mozos3, J. Tjiputra4,2, A. Olsen1,2, J. D. Müller6, I. E. Huertas7, T. T. T. Chau5, V. Cainzos8, A. Velo3, G. Bernaed5, J. Hauck9, N. Gruber6, R. Wanninkhof10

1University of Bergen, Bergen, Norway. 2Bjerknes Centre for Climate Research, Bergen, Norway. 3CSIC, Vigo, Spain. 4NORCE, Bergen, Norway. 5LSCE/IPSL, Paris, France. 6ETH Zürich, Zürich, Switzerland. 7ICMAN-CSIC, Cadiz, Spain. 8IOCAG, Canary Islands, Spain. 9Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany. 10NOAA, Miami, USA

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends 

In this contribution we will present an assessment of carbon budgets and fluxes as well as their trends in the Atlantic Ocean. This work is part of the Regional Carbon Cycle Assessment and Processes project (RECCAP2). We compare the patterns and trends in surface ocean pCO2 and air-sea CO2 flux estimated from observation-based upscaling products (pCO2 products) and global ocean biogeochemical models (GOBMs). While they agree reasonably well in their estimates of the overall carbon uptake, we identified major uncertainties still connected to the carbon fluxes from river derived carbon, the misrepresentation of the pCO2 seasonal cycle in temperate regions in most GOBMs, and a diverging estimate of air-sea CO2 flux estimated by pCO2 products vs GOBMs. We also compare the mean accumulation rate of anthropogenic carbon, which was about 30% lower in the GOBMs than in observation based estimates. 


343 Multi-Year Urban Total Column Network Observations – Challenges and Insights of Using MUCCnet for Emission Estimates

Oral

Jia Chen*, Moritz Makowski, Friedrich Klappenbach, Andreas Luther, Vigneshkumar Balamurugan, Josef Stauber, Florian Dietrich

Environmental Sensing and Modeling, Technical University of Munich, Munich, Germany

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

As a large percentage of anthropogenic greenhouse gases is emitted in urban areas, accurate methods are required to monitor carbon fluxes originating from cities to mitigate climate change. To this end, we established the permanent and automated urban sensor network MUCCnet (Dietrich et al. 2021) for measuring CO2 and CH4 column concentrations. It consists of 5 stations inside and surrounding Munich. 

The MUCCnet data showed an overall ~2.7% increase in XCO2 and ~3% increase in XCH4 over the last 4.5 years (09/2019-03/2024). In addition, we detected small, but noticeable gradients between the downwind and upwind stations of the city, up to 3 ppm for XCO2 and 10 ppb for XCH4. These downwind-upwind city gradients were inversely proportional to the wind speed. We used a mass-balance approach to infer the emissions from the gradients. The city center with many emission sources nearby was, however, not always suited as an upwind location in the mass-balance approach, which highlights the necessity of a sophisticated inverse modeling approach. In addition, we were able to validate satellite gradient measurements over Munich using MUCCnet (Rißmann et al. 2022). 

For assessing urban emissions using such small signals, high accuracy and precision of the gradient measurements are required. To this end, we used Xair characteristics, e.g. slope and offset, for diagnostics of anomalies and developed a novel calibration strategy to account for drifts of pressure sensors and changes of optical properties of the EM27/SUN spectrometers. Further, different methodologies to determine the true background of the city were investigated.

 

344 The Potential of night-time observation applications in atmospheric inversions based on CarboScope-Regional system

Poster

Yang XU1*, Michał Gałkowski1,2, Ðanilo Custódio1, Christoph Gerbig1

1Department of Biogeochemical Signals, Max Planck Institute for Biogeochemistry, Jena, Germany. 2Faculty of Physics and Applied Computer Science, AGH University of Kraków, Kraków, Poland

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Inversion modelling has become a widely-used tool for the estimation of greenhouse gas emissions. This top-down approach leverages a combination of observational data and modelling techniques to reduce the uncertainties in pre-existing emission inventories. Traditionally, the application of inversion modelling has been restricted predominantly to the afternoon hours, when atmospheric conditions are generally considered well-mixed, which in turn ensures that the transport errors in models are kept to a minimum. Hence, there is a considerable untapped potential in the observational records collected at other times of the day, which could help enhance our understanding of the diurnal patterns of greenhouse gas emissions.

We have examined the vertical profiles of nocturnal meteorological parameters with data from both ICOS towers and radiosondes at nearby stations during various seasons and weather conditions, in order to assess the viability and establish criteria for utilizing nighttime carbon dioxide (CO2) observations. To ascertain the well-mixed partial column below the tower heights, we employed an improved algorithm for retrieving nocturnal mixing layer height.  We also present preliminary results from inversion runs of CarboScope-Regional (CSR) system, run over Europe for the year 2022. By implementing partial column CO2 concentrations in CSR, we were able to obtain updated diurnal CO2 flux fluctuations, which allowed us to assess the influence of using nighttime data on its components, specifically vegetation respiration and photosynthesis.

 


345 Quantifying uncertainty in CO2 air-sea exchange on the Belgian continental shelf

Poster

Tom Van Engeland*, Hannelore Theetaert, Silke Verbrugge, Michiel T'Jampens, Coraline Leseurre, Thanos Gkritzalis

Flanders Marine Institute, Oostende, Belgium

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

The atmosphere-ocean exchange is a critical ecosystem component in alleviating effects of anthropogenic CO2 inputs into the atmosphere. This atmosphere-ocean CO2 exchange is often modeled as the product of a rate constant and difference in CO2 partial pressure. Several empirical formulations with focus on global scales exist that link the rate constant to wind speed. Using data from the ICOS station, Thornton Buoy, we investigate the contribution of this diversity in exchange rate formulations in the uncertainty in CO2 exchange on the local scale of the Belgian continental shelf. This uncertainty is evaluated against a background of variability in factors influencing CO2 uptake in a typical coastal marine system with river inputs.


346 Micrometeorological measurements of methane and carbon dioxide emissions at landfills

Poster

Maiju Linkosalmi*, Tuomas Laurila, Juuso Rainne, Juha Hatakka, Juha-Pekka Tuovinen, Mika Aurela, Timo Mäkelä, Hermanni Aaltonen

Finnish Meteorological Institute, Helsinki, Finland

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

The waste management sector accounted for almost four percent of Finland's total greenhouse gas emissions in 2022. Emissions from municipal waste disposal accounted for 80% of the emissions of the waste management sector. The percentage of methane emissions from landfills was 30% of the total anthropogenic methane emissions. The greenhouse gas emissions from landfills are mainly comprised of landfill gas, which forms when organic material decomposes anaerobically. The landfill gas consists mostly of methane and carbon dioxide. Landfilling of municipal organic waste was banned in 2014, but gas production continues for many decades. The waste treatment facilities aim to extract and collect landfill gas and utilize it, for example, in biogas, electricity or heat production.
 
 We have been applying the micrometeorological eddy covariance method for measuring greenhouse gas emissions from landfills. With eddy covariance method, the gas exchange between the surface and atmosphere can be measured continuously. The measurements of methane and carbon dioxide emissions have been conducted in several landfill sites over the years.
 
 With these measurements, it is possible to evaluate annual emissions from a landfill and even spot individual events, such as higher emissions due to disturbances in the gas collection system or construction work. It is also possible to combine these measurements with gas collection information and evaluate the efficiency of the gas collection system and the total methane production of the landfill (amount of collected gas and measured emission). In this presentation we show examples of the above mentioned applications from different landfill sites.


347 A new wavelet-based-direct-partitioning eddy covariance CO2 fluxes workflow evaluated in ICOS

Oral

Pedro Herig-Coimbra1*, Giacomo Nicolini2, Carlo Trotta2, Dario Papale3, Benjamin Loubet1

1ECOSYS, INRAE, AgroParisTech, Université Paris-Saclay, Palaiseau, France. 2Euro-Mediterranean Center on Climate Change (CMCC), Viterbo, Italy. 3National Research Council (CNR), IRET, Monterotondo (Roma), Italy

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Monitoring net ecosystem exchange (NEE) between ecosystems and the atmosphere is crucial to quantifying the net biospheric CO2 uptake worldwide. NEE is currently monitored over thousands of ecosystem sites worldwide by the Eddy Covariance method (EC). However, photosynthesis (gross primary productivity, GPP) and ecosystem respiration (Reco) are the most valuable information to understand ecosystem functioning and among the most used in remote sensing and modelling. These are currently derived from NEE by partitioning methods that involve models, most typically fitting a Reco response to temperature or GPP to solar radiation. 

This study evaluates a new wavelet-based-direct-partitioning eddy covariance method proposed by Herig-Coimbra et al. (2024) on 39 ICOS ecosystem Class 1 and 2 sites, for which the raw data and all the metadata are available. The method uses wavelets to compute the NEE. It then splits positive and negative parts of the wavelet decomposed NEE conditioned by the water vapour flux to compute GPP and Reco.

Here we evaluate the robustness of the wavelet method in computing NEE and heat fluxes over the 39 ICOS sites, and compare them to the standard-EC fluxes estimates. In addition, the agreement of seasonal and monthly dynamics of GPP and Reco as estimated by the two methods are evaluated. 

 

348 From science to services: towards the Copernicus greenhouse gas emission monitoring service.

Poster

Richard Engelen1*, Anna Augusti-Panareda2, Ernest Koffi1, Nicolas Bousserez1, Luca Cantarello1, Aura Lupascu1, Panagiotis Kountouris1, Auke Visser1

1ECMWF, Bonn, Germany. 2ECMWF, Reading, United Kingdom

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Global warming is one of the biggest issues facing the world today. Following the Paris Agreement, 195 countries have pledged to reduce their greenhouse gas emissions, but it is difficult for them to judge whether their measures are successful. As a result, a transparent system to monitor and report emissions is required.

The Copernicus Atmosphere Monitoring Service (CAMS), implemented by ECMWF on behalf of the European Commission, is being extended with a new global monitoring and verification support capacity for anthropogenic CO2 and CH4 emissions (CO2MVS), using the complementarity of observations and computer models. While the main focus will be on exploiting the observations from the current and future Sentinel missions, such As Sentinel-5p, Sentinel-5, and CO2M, other satellite observations will be used as well together with the increasing number of ground-based observations.

Using these observations and the Earth System modelling and data assimilation capabilities of CAMS, the new CO2MVS capacity is expected to deliver from 2026 onwards consistent and reliable information in support of informed policy- and decision-making processes, at city, national and European level. 

This presentation will provide an update on the status of the implementation of the CAMS CO2MVS and especially how various EU-funded research projects, such as CoCO2, CORSO, CATRINE, and others, are contributing to the ramping up of this important initiative. Examples of specific developments and how they prepare the grounds for an operational implementation will be given.


349 Complementing regional scale GHG flux observations with area-specific emission signatures.

Oral

Anastasia Gorlenko*, Konstantinos Kissas, Charlotte Scheutz, Andreas Ibrom

Technical University of Denmark, Kongens-Lyngby, Denmark

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

We are developing a regional greenhouse gas (GHG) observation system in a Danish rural area West of Copenhagen. The general aim is to quantify the emissions of an agriculture-dominated area using high-resolution micrometeorological sensors placed at different heights along a telecommunication tower. The system quantifies the surface fluxes of 4 different GHG (CO2, CH4, N2O, CO) and represents sources and sinks within a 5km radius around the tower. The changing weather conditions (e.g.: wind speeds, wind directions, and atmospheric stability) favor the coverage of varying parts of the heterogeneous landscape. The multiple-gas and multiple-heights system is used to attribute the measured GHG fluxes to specific areas and processes in the landscape.  

To help the interpretation of the measured GHG fluxes and ease the attribution step, we gathered information on the area around the tower. We used data from a CCTV camera to develop a traffic count and estimate the emissions coming from the roads. An inventory of the local farms and their management practices was built to estimate the emissions signatures of farmlands and crop fields. Forest and vegetation areas were characterized using a simple light response model. 

We would like to present the tall tower eddy covariance system and 11 months of surface fluxes data characterizing the emissions/sinks of 4 GHG along changing seasons in a rural landscape. We would like to discuss how the bottom-up emissions modelling can help optimize the source attribution of measured GHG fluxes at a regional scale.


350 Long-term monitoring of CO2 emissions over Switzerland using observations and forward simulations of 14CO2

Oral

Dylan Geissbühler1,2*, Thomas Laemmel3,2, Stephan Henne4, Dominik Brunner4, Philip Gautschi5, Lukas Wacker5, Sönke Szidat1,2

1Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland. 2Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland. 3Department of Chemistry, Biochemistry and Pharmaceutical Sciences, Bern, Switzerland. 4Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, Switzerland. 5Laboratory of Ion Beam Physics, Institute for Particle Physics and Astrophysics, Federal Institute of Technology Zurich (ETHZ), Zürich, Switzerland

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Atmospheric modelling of greenhouse gases (eg. CO2 and CH4) emissions is a precious tool for establishing inventories for the type and magnitude of sources at a national scale. Especially, forward modelling allows for the comparison of existing emission inventories with discrete measurements. This then allows for the refinement of said inventories in terms of source fluxes, both in a spatial and temporal way. Additionally to concentration, isotopic signatures can be added to the model to gain insight on the types of sources. For CO2, 14C in particular allows the separation between modern and fossil sources, which is crucial in the context of emission stock-taking and mitigation.

Switzerland is a densely inhabited and industrialized country in its northern half, with the Alps spanning its southern half, combining small size with high diversity of land type. Here, we study CO2 emissions over Switzerland for a 2-year period using forward modelling of CO2 and its isotopologues 14CO2 and 13CO2. Simulated results are compared to measurements taken at five sampling sites over the Swiss Plateau during the same period.

Our model aims at replicating the measured values for CO2 and 14CO2 by refining ecosystem respiration fluxes and isotopic values as well as the influence of Swiss and European nuclear power plants. This will provide additional constraint on the evaluation of the current Swiss national emission inventory.


351 Optimizing CO2 emission estimates in Paris through enhanced urban atmospheric monitoring

Oral

Ke Che1,2*, Thomas Lauvaux1,2, Ingrid Chanca1, William Morrison3, Charbel Abdallah2, Carla Dangeli2, Samuel Hammer4, Andreas Christen3, Dana Looschelders3, Simone Kotthaus5, Martial Haeffelin5, Olivier Sanchez6, Olivier Perrussel6, Morgan Lopez1, Philippe Ciais1, Leonard Rivier1, Michel Ramonet1

1LSCE, Paris, France. 2GSMA, Reims, France. 3University of Freiburg, Freiburg, Germany. 4Heidelberg University, Heidelberg, Germany. 5Institut Pierre-Simon Laplace (IPSL), Paris, France. 6Airparif, Paris, France

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Paris, as part of the EU-funded PAUL project (ICOS Cities), is at the forefront of cities committed to reducing CO2 emissions. This commitment is supported by an extensive urban atmospheric monitoring network, comprising nine towers equipped with 14 high-resolution and mid-cost detectors, designed to detect significant changes in emissions. The Stochastic Time-Inverted Lagrangian Transport (STILT) model is utilized for backward runs of CO2 enhancement from established inventories between March and September 2023. Significant reduction in transport error is achieved through the assimilation of three-dimensional wind profiles from Lidar data over Paris, employing the Weather Research and Forecasting model with Data Assimilation (WRF-DA). Three fossil fuels (TNO, Airparif and ODIAC) and three biogenic (SMURF, SMAP and offline VPRM) emission inventories are taken as priors, our inverse modeling framework utilizes an well-established Bayesian inversion technique with adaptive mesh grids (1km in the downtown gradually aggregated to 50 km across the region). This approach aims to minimize computational costs without sacrificing inversion accuracy near sites. Our results revealed notable differences in fossil fuel estimates adjustment and even greater disparities in biogenic emissions across Paris. To further validate and refine these estimates, radiocarbon(14C) observations from two Parisian sites were introduced as tracers. This innovative method estimates fossil-fuel CO2 (ffCO2) based on observed 14C-CO2 depletion relative to a clean background station, significantly improving the accuracy of distinguishing between fossil fuel and biogenic urban CO2 emissions and reducing the uncertainties in optimized emissions. Our findings emphasize the importance of leveraging a diverse array of observational sources to accurately evaluate CO2 emissions across Paris.


352 The AVENGERS Horizon Europe project: Attributing and Verifying European and National Greenhouse gas and aerosol Emissions and Reconciliation with Statistical bottom-up estimates

Poster

Marko Scholze*, AVENGERS Team

Lund University, Lund, Sweden

Session 13. In situ data for climate and other environmental services and policy support

The reporting of national greenhouse gas emission inventories is a crucial element in the Paris Agreement. However, the reported emissions carry susbtantial uncertainties and are lacking independent verification using the atmospheric records. The AVENGERS (Attributing and Verifying European and National Greenhouse gas and aerosol Emissions and Reconciliation with Statistical bottom-up estimates) project brings together European experts to establish top-down techniques in support of the verification of national greenhouse gas (GHG) inventories. AVENGERS will make use of atmospheric inverse modelling and data assimilation, remote sensing, environmental monitoring and observation, terrestrial ecosystem modelling, policy and stakeholder interaction together with national inventory compilers in order to improve consistency of the inventory-based GHG emission reports with top-down approaches. AVENGERS will advance the top-down approach for quantifying GHG and aerosol emissions by adding additional tracers (e.g. radiocarbon, co-emitted species, black carbon), as well as reconcile and integrate approaches into a joint bottom-up and top-down framework. Based on the reconciliation, AVENGERS will prepare good-practice guidelines for use of atmospheric inverse models as well as develop a Flexible Inversion Tool for Inventory Compilers (FIT-IC). Knowledge and outcomes are provided for policy and societal stakeholders and replicable outside of our chosen target area (Europe with a focus on Germany, Italy, Sweden, Switzerland, and The Netherlands). The uniqueness of the consortium lies in the combination of the required scientific expertise with full partner presence of official reporting agencies from exemplary EU countries facilitating the transfer of knowledge to key international organizations (such as UNFCCC, WMO) in the field.


353 Methane trends at northern high latitudes estimated by atmospheric inverse modeling

Poster

Tuula Aalto*, Anttoni Erkkilä, Maria Tenkanen, Aki Tsuruta, Kimmo Rautiainen, Hannakaisa Lindqvist

Finnish Meteorological Institute, Helsinki, Finland

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Methane emissions at northern high latitudes have been studied using Earth Observing (EO) satellite data, in situ measurements and global atmospheric methane inversion model (CTE-CH4) estimates.  Atmospheric observations from the ICOS sites and other in situ networks were used to perform atmospheric inversion model simulations to quantify natural and anthropogenic emissions over recent decades (2000-2021). Investigations of methane (CH4) sources in the northern high latitudes were extended to permafrost and non-permafrost regions, and their relationships with environmental drivers such as seasonal soil freezing, vegetation activity, precipitation and temperature were examined. Fluxes were optimized weekly to enable seasonal emission estimations, including the shoulder seasons when emissions undergo rapid changes. It was found that late summer and autumn periods showed significant increasing trends in methane emissions. Emissions were positively correlated with variables directly or indirectly related to the vegetation activity.

 


354 ASSESSING METHANE EMISSIONS FOR MEGACITY MUMBAI, INDIA USING SATELLITE DATA

Poster

Shruti Uphale*, Anurag Kandya, Viral Patel, Shubham Kela, Kaivalya Gadekar

Pandit Deendayal Energy University, Gandhinagar, India

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

As a greenhouse gas, methane plays a critical role in climate change. Anthropogenic emission of greenhouse gases has led to a significant increase in atmospheric methane concentrations on a global scale. However, the knowledge regarding the spatial and temporal distribution of methane at a city scale is still poor. Bridging this gap, the present study puts forward the spatio-temporal variations of columnar methane concentration across Mumbai city.  

The study uses the remotely sensed data generated through TROPOMI instrument aboard the Sentinel 5P satellite for a period of 4 years (January 2019 – December 2022) and presents the ward specific averages for different time periods – monthly, seasonal and annual. At a city level, the study estimates that methane has increasing at the rate of 13.48 ppb / year [1886 ppb (2019), 1900 ppb (2020), 1918 (2021) and 1925 (2022)]. The monthly average analysis reveals that the month of May (which represents a summer season) witnesses the minimum concentration of the entire year while the months of October-November (which represent a post monsoon season) witness the highest concentration of the year. The outcomes of the study would provide crucial inputs to Maharashtra Pollution Control Board for strengthening their action plan for reducing the Green House Emissions.

 

355 Freshwater carbon fluxes at high northern latitudes

Poster

Judith Vogt1*, Anna-Maria Virkkala2, Isabel Wargowsky2, McKenzie Kuhn2, Simran Madaan1, Mathias Göckede1

1Max Planck Institute for Biogeochemistry, Jena, Germany. 2Woodwell Climate Research Center, Falmouth, USA

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

The high northern latitudes are characterized by a large number of waterbodies that act as carbon sources to the atmosphere in an environment that is predominantly characterized by carbon sequestration. Ongoing permafrost thawing in the warming Arctic is expected to alter the distribution of freshwater ecosystems and consequently their contribution to the overall carbon budget.
 Estimates of global carbon budgets largely ignore emissions from permafrost thaw, and the carbon budgets of freshwater ecosystems are highly uncertain. A limiting factor is data scarcity in remote northern regions. In addition, the underlying processes specific to freshwater ecosystems remain poorly understood, especially given the landscape heterogeneity at high northern latitudes. To fill these gaps, we synthesize new and existing carbon dioxide (CO2) and methane (CH4) flux data from freshwater ecosystems and environmental parameters (temperature, pH, water depth, etc.) across the Arctic-boreal domain at site level and monthly resolution.
 This work will contribute to the Arctic-Boreal Carbon flux synthesis (ABCflux v2), which includes terrestrial, wetland and freshwater ecosystems. We collected data from over 1,000 different freshwater sites with more than 3,000 monthly CO2 and CH4 flux measurements. With the newly synthesized data, we will quantify the carbon budgets of freshwater ecosystems across the Arctic-boreal domain and assess their contribution to the global carbon budget. In addition, the influence of environmental controls such as temperature, pH and water depth on carbon cycling processes will be investigated. This dataset will provide a unique opportunity for benchmarking and verification of process-based models and remote sensing products.


356 PARIS, AVENGERS, EYE-CLIMA - Verification and reconciliation of estimates of climate forcers

Oral

Sylvia Walter1*, Anita Ganesan2, Thomas Röckmann1, Marko Scholze3, Rona Thompson4

1Utrecht University, Utrecht, Netherlands. 2University of Bristol, Bristol, United Kingdom. 3University of Lund, Lund, Sweden. 4NILU, Kjeller, Norway

Session 13. In situ data for climate and other environmental services and policy support

PARIS, AVENGERS, and EYE-CLIMA represent initiatives funded under the EU Horizon call focused on "Verification and reconciliation of estimates of climate forcers." Drawing expertise from diverse fields such as atmospheric science, ecology, computer science, systems analysis, climate, and emissions reporting, these projects collaborate with the shared objective of refining estimates of greenhouse gas (GHG) emissions through observation-based methodologies. This collaborative effort not only aims to enhance the precision of GHG emission estimates but also facilitates meaningful exchanges with stakeholders involved in policymaking, national greenhouse gas inventories (NGHGIs), government bodies, and non-governmental organizations.

Utilising atmospheric inversion models, the three projects establish connections between surface-atmosphere GHG exchanges and atmospheric concentrations. The emissions estimates derived through this method directly correlate with atmospheric observations, remaining independent of activity data and emission factors. Consequently, this approach supports the independent verification of NGHGIs. In essence, PARIS, AVENGERS, and EYE-CLIMA strive to reconcile emissions information to contribute to the effective implementation of the Paris Agreement. Beyond atmospheric inversion methods, the projects incorporate land-surface models, which simulate the processes governing GHG exchanges between the land surface and atmosphere, along with data-driven models. 

This presentation will provide a comprehensive overview of the three projects, delving into their individual objectives and highlighting the overarching efforts aimed at verifying and reconciling estimates of climate forcers.

 

357 Peatland ecosystem model development for investigating climate impacts of land use options

Poster

Tiina Markkanen1*, Tuula Aalto1, Ellinoora Ekman2, Kielo Isomäki1, Antti Leppänen2, Xuefei Li2, Suvi Orttenvuori1, Henri Sulkava1, Ville Tuominen1, Maarit Raivonen2

1Finnish Meteorological Institute, Helsinki, Finland. 2University of Helsinki, Helsinki, Finland

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

Peatlands are naturally long lived stores of carbon in their water logged soil layers. Management of peatlands for forestry or agriculture typically involve drying of soils, that consequently increase emissions from the faster decomposing soil carbon pools. Re-wetting of formerly drained peatlands has been suggested as a measure to mitigate or compensate human induced green house gas emissions.

We use a process model framework JSBACH-HIMMELI in various national and European projects to investigate the climatic responses of different land use scenarios at the peatlands. JSBACH is a land surface model including vegetation and soil carbon cycle and surface energy balance. HIMMELI accounts for methane production and transport within the soil profile.

Among other things, we seek ways to implement functionalities of various wetland species in the model framework. We improve soil carbon decomposition formulations to better account for the impact of water table dynamics on the total soil carbon storage. We aim to develop the CH4 model to include in it the essential features required for simulating different peatlands and different management effects on them. We adjust the parameters related to wetland surface energy balances. To evaluate the model performance we use eddy covariance and chamber measurements.

With the improved model framework we will produce more reliable responses of the wetland ecosystems on the land use change and climate change scenarios. Moreover, we include the relevant improvements to our framework producing yearly updates for European CO2 and CH4 flux fields used in the ICOS based atmospheric inversion framework.

 

358 Recent inorganic carbon increase in a temperate estuary driven by water quality improvement and enhanced by droughts

Oral

louise rewrie1*, Burkard Baschek2, Justus van Beusekom1, Arne Körtzinger3, Gregor Ollesch4, Yoana Voynova1

1Helmholtz-Zentrum Hereon, Geesthacht, Germany. 2German Oceanographic Museum, Stralsund, Germany. 3GEOMAR, Helmholtz-Zentrum für Ozeanforschung Kiel, Kiel, Germany. 4Flussgebietsgemeinschaft Elbe (FGG Elbe), Magdeburg, Germany

Session 7. Carbon Cycling along the Land Ocean Aquatic Continuum

Estuaries are an important component of the global carbon budget, facilitating carbon removal, transfer and transformation along the land-ocean continuum. A recent (1997-2020) significant increase in dissolved inorganic carbon (DIC) of 6–21 µmol kg-1 yr-1 in a temperate estuary (Elbe Estuary, DE), was driven by an increase in upper estuary particulate organic carbon (POC) of 8–14 µmol kg-1 yr-1. The temporal POC increase was due to an improvement in water quality observed in the form of dominating autotrophy and a significant drop in BOD7. This POC increase was on the same magnitude as the DIC increase in the estuary, suggesting that POC is effectively remineralized and retained as DIC by the mid-estuary. An extensive drought period (2014–2020) modulated this trend by significantly lowering the annual mean river discharge (468 ± 234 m3 s-1) compared to the long-term mean (690 ± 441 m3 s-1, 1960–2020). During the drought period, the late spring internal DIC load in the estuary doubled. This suggests that the drought induced a longer dry season, starting in May (earlier than normal), increased the residence time in the estuary and allowed for a longer remineralization period for POC. Annually, the Elbe Estuary represents a source of inorganic carbon to the atmosphere and to the coast. Comparing the fluxes during drought and non-drought years, there was no change in the water-air flux, but a significant decrease in the lateral DIC export from the estuary during drought years, by on average 24%.


359 An improved downscaling method for city-scale European GHG inventories: insights learned from comparisons with Munich, Zurich and Paris local inventories

Oral

Emma Schoenmakers1*, Ingrid Super1, Hugo Denier van der Gon1, Tilman Hohenberger1, Daniel Kühbacher2, Patrick Aigner2, Jia Chen2, Dominik Brunner3, Olivier Perrussel4, Michael Suhendra2, Beyza Yirtar2

1Netherlands Organisation for Applied Scientific Research (TNO), Utrecht, Netherlands. 2Technical University of Munich (TUM), Munich, Germany. 3Swiss Federal Laboratories for Materials Science and Technology (EMPA), Dübendorf, Switzerland. 4Airparif, Paris, France

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

High-resolution emission inventories are the cornerstone for modelling and mitigation of greenhouse gases (GHG) in urban areas. European inventories, such as CAMS-REG or TNO-GHGco, are available at up to 1km resolution and provide results with a standardized methodology. However, they require higher spatial resolution needed for urban applications.

The ICOS Cities (PAUL) project, aims to develop an integrative approach to urban measurements to better support stakeholder uptake and reach of climate targets. To develop a generic approach to making urban emissions inventories for European cities, we compared the bottom-up inventories of the cities of Zurich, Munich and Paris to spatially downscaled emissions from the TNO-GHGco inventory for GHGs (CO2 and CH4) and co-emitted species (CO, NOx, BC) down to 100m scale for 12 sectors such as industry, road transport and residential combustion. A detailed comparison between these approaches is beneficial for 1) knowledge sharing 2) downscaling regional inventories for urban applications 3) supporting cities that lack the infrastructure to develop a ‘bottom-up’ urban inventory independently.

For each city, the TNO-GHGco inventory was downscaled using sector-specific spatial proxies such a gapfilled OpenStreetMap/OpenTransportMap vector-based data for transport emissions. Results show good agreements for spatial emission patterns in road transport and residential combustion, and less good agreements for off-road emissions due to local information on major construction sites in the bottom-up inventory. These comparisons make it possible to test and verify improvements to regional inventories.


360 GHG budget estimates from polyisotopic carbon dioxide (CO2) at Weybourne Atmospheric Observatory (WAO), north Norfolk, United Kingdom

Poster

Jan Kaiser1*, Penelope A. Pickers1,2, Grant L. Forster1,2, Alina D. Marca1, Andrew C. Manning1, Richmal Paxton1

1Centre for Ocean and Atmospheric Sciences (COAS), School of Environmental Sciences, University of East Anglia (UEA), Norwich, United Kingdom. 2National Centre for Atmospheric Science (NCAS), University of East Anglia (UEA), Norwich, United Kingdom

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Polyisotopic carbon dioxide (CO2) ratios are relatively new tools to improve our understanding of greenhouse gas cycles. We define polyisotopic elements as elements with more than one minor isotope (e.g., 17O and 18O next to the most abundant 16O) and contrast them with polyisotopologues as compounds with two rare isotopes in the same molecule (e.g., 13C18O16O). Our UK Natural Environment Research Council (NERC)-funded project POLYGRAM (POLYisotopologues of GReenhouse gases: Analysis and Modelling) makes targeted observations of both kinds of polyisotopic species to quantify and analyse their meridional and temporal variations, as well as characterise source fingerprints.

CO2 polyisotope budgets allow estimating gross primary productivity, but require leaf and soil water isotope ratios and isotopic fractionations associated with transport and uptake. Simultaneous measurements of δ(18O) and δ(17O) simplify these requirements since δ(17O) variations are correlated with δ(18O). The deviation of δ(17O) from a mass-dependent correlation with δ(18O) is expressed as the ‘triple oxygen isotope excess’, Δ(17O). Variability in Δ(17O) only depends weakly on the δ(18O) of soil and leaf water, simplifying productivity estimates.

In this paper, we present a 2.5-year in-situ record of simultaneous 13C/12C and oxygen triple isotope (16O, 17O, 18O) ratio measurements using an Aerodyne tuneable infrared laser direct absorption spectrometry (TILDAS) instrument at the UEA-NCAS ICOS Weybourne Atmospheric Observatory at the north Norfolk coast. Initial results gave a measurement precision of 4 ppm for Δ(17O) over 30 min. We also quantify variability on seasonal and diurnal scales.


361 Historic debt and future mitigation potential: How much of the greenhouse gas emissions from global palm oil production can we cut by 2050?

Oral

Alexander Röll1,2, Najeeb A.A. Iddris3, Michael Köhler4, Martin Ehbrecht5, Thomas Guillaume6, Jens Leifeld7, Cristina de la Rua8, Ana Meijide3*

1University of Bonn, Horticultural Sciences, Institute for Crop Science and Resource Conservation, Bonn, Germany. 2University of Göttingen, Tropical Silviculture and Forest Ecology, Göttingen, Germany. 3University of Bonn, Environment Modeling, Institute for Crop Science and Resource Conservation, Bonn, Germany. 4Northwest German Forest Research Institute, Göttingen, Germany. 5University of Göttingen, Silviculture and Forest Ecology of the Temperate Zones, Göttingen, Germany. 6Agroscope, Field-Crop Systems and Plant Nutrition, Nyon, Switzerland. 7Agroscope, Climate and Agriculture Group, Zürich, Switzerland. 8Technical University of Munich, Electrical and Computer Engineering, Renewable and Sustainable Energy Systems, Munich, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Oil palm is a major oil crop and its extent is projected to further increase. Oil palm cultivation is associated with high greenhouse gas (GHG) emissions but a comprehensive analysis of global GHG footprints is lacking. Previous studies point to differences in GHG emissions among young and mature plantations, plantations converted from forest vs. degraded land, first rotation cycle plantations vs. subsequent cycles and plantations on peat vs. mineral soils, which should be considered when assessing GHG footprints. We combine FAO data on oil palm extent and yield, age class simulations, remote sensing approaches to determine soil types and land-use origins and enhanced life cycle analysis with field-measured data to derive global past, current and future oil palm cultivation GHG footprints. The preliminary results indicate that from 1940 to 2022, the actual cumulative GHG emissions from oil palm cultivation were about four times higher than under a hypothetical sustainable land-use scenario entirely avoiding deforestation and plantations on peat. Compared to a business-as-usual scenario that assumes further growth in oil palm extent but no substantial changes in land-use management until 2050, the cumulative GHG emissions (2023 – 2050) could still be slashed substantially by smart land-use choices today, with mitigation potentials of up to 10% through sustainable intensification, up to 15% through peatland and forest moratoria for new plantations and up to 25% when additionally abandoning all existing oil palm cultivation on peat. To access these substantial mitigation potentials, a globally coordinated approach also fostering soil and biodiversity protection is needed. 

 

362 Asymmetry response of carbon and water fluxes to extreme drought in Savanna

Poster

Gnanamoorthy Palingamoorthy*, Song Qinghai, Zhang Yiping

Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Xishuangbanna, China

Session 5. Impact of climate extremes on GHG fluxes: understanding driving processes and responses across scales

The savanna ecosystem plays a significant role in terrestrial carbon and water cycles. Climate change predicted to bring more frequent and intense droughts in the future, particularly in tropical climates. Understanding the impacts of these droughts on carbon and water fluxes in tropical savannas is essential. We studied an extreme drought event that occurred in a China’s savannas in southwestern China in 2019 and used 7 years (2016–2022) of net ecosystem CO2 exchange (NEE), and ET data to investigate the effect of the event on the ecosystem. Notably, water use efficiency (WUE) exhibited a significant increase of 41% during the drought and a 39% increase during the post-drought years when compared to the pre-drought years. This improvement was primarily driven by a 26% reduction in ET during the drought and a 21% reduction during the post-drought period. Gross primary productivity (GPP) showed insignificant changes during any of the study periods. Contrast, ecosystem respiration (Reco) decreased by 11% during the drought and 23% during the post-drought years compared to the pre-drought years, contributing to increased carbon sequestration during these periods. Overall, our results revealed an asymmetrical response of carbon and water fluxes. During the post-drought period, the carbon sink increased due to decreased Reco. However, water fluxes decreased due to limited water conditions in the ecosystem and the water-saving strategies employed by savanna ecosystems during drought events and their legacy periods. These findings offer valuable insights for understanding impact of extreme drought scenarios in savanna ecosystems.

 

363 Using ammonia to split methane contributes of different sources in the Netherlands

Oral

Jun Zhang1*, Pim van den Bulk1, Ilona Velzeboer1, Harmen Manson1, Baye Thera1, Paula Bronsveld1, Enrico Dammers2, Martijn Schaap2, Arjan Hensen1, Daniëlle van Dinther1, Gerrit Jan de Bruin2

1TNO, Petten, Netherlands. 2TNO, Utrecht, Netherlands

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Only recently, the option is available to do high-frequency ammonia (NH3) concentration measurements (at 10 Hz) with the same time resolution as methane during the mobile drive. Using an open-path NH3 monitor (HT8700E) mounted on the roof of a TNO mobile GHG gases measurement truck, in combination with an Aerodyne TILDAS for CH4-C2H6-CO-CO2-N2O-H2O instrument, mobile measurements were carried out in multiple source regions in the Netherlands. We will show how different sources can be recognized and quantified using their NH3/CH4 ratios, similar to what we’ve done before with the C2H6/CH4 ratio for oil and gas sources. We will demonstrate the results from various measurement campaigns in 2022, 2023 and 2024 and discuss the methane emissions from dairy, pig, poultry housing, manure application, and traffic sources in the centre of the Netherlands.   

 

364 GREENHOUSE GAS FLUXES AND THEIR DRIVERS IN LARGE NORTHERN BOREAL LAKE PALLASJÄRVI

Oral

Joonatan Ala-Könni*

University of Helsinki, Helsinki, Finland

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

Due to global warming the magnitude of GHG release from high-latitude lakes is posed to increase with increasing water column temperature and shortening ice-on period. Although this is a well recognized fact, there remains numerous uncertainties in our knowledge on lake GHG fluxes.

Here, we present results based on a three year long dataset of carbon dioxide and methane fluxes collected via the eddy covariance (EC) method over a large subarctic Lake Pallasjärvi in Finnish Lapland. EC measurements are supplemented by meteorological parameters, radiation, water side measurements of pCO2, pCH4 and temperature stratification as well as flux chamber measurements. This dataset provides a look into the often overlooked aspects and drivers of lake gas fluxes: diurnal, seasonal and annual variation of fluxes, fluxes during the shoulder seasons (spring and autumn) and during the corresponding overturns of the water column and in general methane flux observations over a large subarctic lake, on which measurements from past are few and far between.

The results obtained show that the lake exhibits a large spatial as well as temporal variation in GHG fluxes. The two basins sampled show a strikingly different behavior: The deep, sparsely vegetated main basin emits very little GHG’s into the atmosphere, while on the other hand the shallow, heavily vegetated basin has almost an order of magnitude higher GHG fluxes observed over the open water season.


365 PARIS - PROCESS ATTRIBUTION OF REGIONAL EMISSIONS

Poster

Sylvia Walter1*, Anita Ganesan2, Aoife Grant2, Thomas Röckmann3

1Utrecht University, Utrecht, Netherlands. 2University of Bristol, Bristol, United Kingdom. 3University of Utrecht, Utrecht, Netherlands

Session 13. In situ data for climate and other environmental services and policy support

PARIS is a HorizonEurope research project that aims to significantly increase our knowledge about greenhouse gas emissions, the evaluation & combination of scientific approaches and a progressive use of collaborative data. 

17 European partners focus on emissions of common greenhouse gases such as carbon dioxide, methane and nitrous oxide, and new emissions estimates for fluorinated gases (F-gases). 

For greenhouse gases with a more complex mixture of sources, methane and carbon dioxide, research in PARIS focuses on the attribution of fluxes to particular sources and sinks. We will advance our world-leading isotopologue measurements and tracer-based analysis methods, providing inventory teams with new information to target areas of uncertainty. For nitrous oxide, a greenhouse gas for which most European inventories rely on highly simplified and uncertain bottom-up methods, two process-level models will be advanced to produce time- and space-resolved estimates that will be evaluated against isotopic data. For the important, but complex, climate forcers, organic matter aerosol and black carbon, we will take the next steps required towards robust top-down emissions inference by developing source apportionment methods. To generate maximum impact, we will synthesise our efforts in the form of draft annual Annexes to National Inventory Reports (NIRs) for eight European PARIS focus countries.

This presentation will give a general overview of the PARIS project, its objectives and implementation. It aims on introducing the project to the scientific community, presenting first results, and setting up a network for future collaborations with related projects, e.g. EYE-CLIMA (https://cordis.europa.eu/project/id/101081395) or AVENGERS (https://cordis.europa.eu/project/id/101081322).

 

366 Europe’s adaptation to the 2022-2023 energy crisis: Reshaped gas supply-transmission-consumption structures and driving factors

Poster

Chunlong Zhou1*, Biqing Zhu1, Antoine Halff2, Steven J Davis3, Zhu Liu4, SimonBen Arous5, Simon Bowring1, Philippe Ciais1

1LSCE, Saint-Aubin, France. 2SIPA Center on Global Energy Policy, New York, USA. 3Department of Earth System Science, University of California Irvine, Irvine, Irvine, USA. 4Department of Earth System Science, Tsinghua University, Beijing, China. 5Kayrros Inc, Paris, France

Session 15. Science communication and outreach to increase the impact of climate research

The invasion of Ukraine by Russia in 2022 triggered a significant energy crisis in the EU27&UK. To understand how Europe adapted to this upheaval, particularly during winter months, we analyzed the pattern shifts of the natural gas supply, transmission, and consumption from the period before the invasion to after, utilizing our innovative natural gas supply-transmission-consumption models and datasets. On the supply side for the post-invasion winters, LNG imports became the largest gas supply source, rising from 21% to 31% of the total gas supply (Russian supply plummeted from 37 % to 5%). However, Russia still accounted for 41% of these LNG imports, as revealed by Automatic Identification System (AIS) data from LNG tankers. Our intra-EU gas transmission analysis highlighted  adjustments made to compensate for significant gas shortages in Germany and to efficiently distribute LNG arrivals. On the consumption side, the largest reduction can be attributed to household heating behavior change (37%), such as  reduced heating usage or switching to the heat pumps. In the power sector, due to the inability of boosting nuclear power, non-fossil electricity can only replace 9% of gas deficits in power generation, leaing to a figure threefold lower than our prediction. We subsequently evaluated the benefits and costs associated with these pattern changes and discussed whether these changes would potentially lead to structural changes in the EU energy dynamics. These insights can provide valuable perspectives for understanding the consequences of this energy crisis and the challenges to future energy security in the EU.

 

367 Setting up a ground-based total column greenhouse gas measurement station in the Democratic Republic of the Congo

Poster

Mahesh Kumar Sha1*, Martine De Mazière1, Yvan Nollet1, Nicolas Kumps1, Filip Desmet1, Patrick Cito Namulisa2,1, Lodewijk Lefevre3, Hans Verbeeck3, Pascal Boeckx3

1Royal Belgian Institute for Space Aeronomy, Brussels, Belgium. 2Columbia University, New York, USA. 3Ghent University, Ghent, Belgium

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

The concentration of major greenhouse gases (GHGs) in the atmosphere is steadily increasing due to emissions from anthropogenic activities. Total-column measurements of GHGs using remote-sensing techniques from ground-based and space-based platforms provide a useful tool for the quantification of GHGs in the whole atmosphere and emission source apportionment. Well-calibrated ground-based measurements are further used to calibrate and validate satellite-based measurements and to establish an indirect traceability to the WMO scale. However, to do a full evaluation of the satellite data a dense distribution of such reference measurements is required around the source-area of interest and covering an extensive range of the measurand space in terms of influencing parameters. In the framework of an ESA project Fiducial Reference Measurements for GreenHouse Gases (FRM4GHG) several portable low-spectral-resolution spectrometers were tested against reference measurements from Total Carbon Column Observing Network (TCCON) and found to be of good quality and capable of complementing the existing reference networks (TCCON & NDACC-IRWG). The low-spectral-resolution FTIRs operate under the umbrella of the COllaborative Carbon Column Observing Network (COCCON). One such low-resolution FTIR, a Bruker-Invenio, is currently in preparation for deployment at the Belgian ICOS Ecosystem site, CongoFlux in Yangambi, DR Congo, which is a data poor region. We will investigate to what extent colocation of the atmospheric and ecosystem sites will be an added value for exchange studies between the biosphere and the atmosphere.

This poster will give an overview of the project objectives, instrument set-up and deployment at the site in DR Congo and show preliminary results.


368 Developing a framework for automated and continuous measurements of FAPAR from distributed wireless sensor Network

Oral

Somnath Paramanik1*, Rémi Grousset2, Gabriele Bai2, Christophe Lerebourg2, Ernesto Lopez-Baeza3, Ana Perez-hoyos3, Alexander Knohl4, Anne Klosterhalfen4, Frank Tiedemann4, Marco Clerici5, Nadine Gobron5, Luke Brown6, Harry Morris7, Jadunandan Dash1

1University of Southampton, Southampton, United Kingdom. 2ACRI-ST, Sophia-Antipolis, France. 3Albavalor, Valencia, Spain. 4University of Göttingen, Göttingen, Germany. 5European Commission Joint Research Centre, Ispra, Italy. 6University of Salford, Manchester, United Kingdom. 7National Physical Laboratory, Teddington, United Kingdom

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

The fraction of photosynthetically active radiation (FAPAR) plays a crucial role in vegetation carbon capture and dynamic vegetation models, requiring accurate and long-term observations for understanding carbon dynamics. Despite advancements in satellite-derived FAPAR products, validating their accuracy remains critical. Current in-situ validation methods, relying on handheld instruments AccuPAR, DHP, and LAI 2200, are labor-intensive and fraught with uncertainties. Conversely, distributed PAR measurements offer continuous monitoring opportunities, especially with wireless connectivity enabling remote, real-time data access and reduced logistical burdens. However, efforts to develop a standardized framework meeting satellite data validation standards have been limited. Addressing this gap, our study developed a FAPAR framework utilizing data from two wireless PAR networks: one in a vineyard site in Valencia Anchor and the other in a forest site at Hainich, as part of the Copernicus Ground-Based Observation for Validation project. Key aspects explored included developing data quality indicators, determining optimal node configurations to represent Elementary Sampling Units (ESUs), and comparing FAPAR estimation methods. At the Valencia Anchor site, 12 nodes equipped with four sensors capturing radiation at canopy top and bottom were deployed in rows. Results showed that a six-node configuration exhibited a stronger correlation (r = 0.81) with observed data compared to other combinations. Additionally, ESU-level 2-flux and 4-flux FAPAR displayed similar patterns with a strong correlation (r = 0.99), with 2-flux FAPAR performing better across different node combinations. These findings contribute to the development of a robust framework and protocol for in-situ FAPAR measurements, essential for validating global satellite-derived FAPAR products.


369 Cross-scale convergence in the carbon balance of managed forests in boreal Sweden

Oral

Matthias Peichl1*, Eduardo Martínez-García1,2, Jinshu Chi3, Natascha Kljun4, Anne Klosterhalfen5, Johannes Larson1, Hjalmar Laudon1, Tomas Lundmark1, Guillaume Monteil6, Mats B. Nilsson1, Anusha Sathyanadh1,7, Marko Scholze6, Jörgen Wallerman8, Peng Zhao1,9

1Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden. 2Natural Resources Institute Finland, Helsinki, Finland. 3The Hong Kong University of Science and Technology, Guangzhou, China. 4Centre for Environmental and Climate Science, Lund University, Lund, Sweden. 5Bioclimatology, University of Göttingen, Göttingen, Germany. 6Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden. 7Department of Energy and Process Engineering, Norwegian University of Science and Technology, Trondheim, Norway. 8Department of Forest Resource Management, Swedish University of Agricultural Sciences, Umeå, Sweden. 9Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas of Ministry of Education, Northwest A&F University, Shaanxi, Sweden

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Boreal forests are globally important carbon (C) sinks, but strategies for maximizing their climate benefit are under debate. Major uncertainties in this discussion arise from contrasting sink-source estimates, which emanate to a large extent from the inherent limitations of standard measurement techniques to distinct spatio-temporal scales. Here, we use a spatially-nested setup of bottom-up (i.e., forest-plot inventory and chamber-based fluxes) and top-down (i.e., eddy-covariance; atmospheric observations and atmospheric transport modelling) approaches to reconcile the C balance of actively managed forests in boreal Sweden across plot-, ecosystem-, landscape-, and regional scales over 3 years (2016-2018). We find that estimates across scales converged into a C sink-strength of 118±27 g C m-2 yr-1 (mean ± 95% confidence interval). We further found greater sensitivity to the 2018 European summer drought in bottom-up compared to top-down estimates. Overall, this study consolidates the C sink-strength of managed boreal forests and advocates for cross-scale assessments to constrain forest C cycle-climate feedbacks.

 


370 The mosaic nature of peatland emission calls for co-learning for science-based mitigation policy and community acceptance

Oral

Christian Fritz1,2*, Quint van Giersbergen1, Tom Nijman1, Tom Heuts1, Ralf Aben1, Reinder Nouta3, Lisanne Hendriks1, Stefan Weideveld1,4, Bart Kruijt5, Ralph Temmink6

1Radboud University, Radboud Institute for Biological and Environmental Sciences (RIBES), Nijmegen, Netherlands. 2IREES University of Groningen, Groningen, Netherlands. 3Wetterskip Fryslân, Leeuwarden, Netherlands. 4B-Ware Research Centre, Nijmegen, Netherlands. 5Wageningen University, Wageningen, Netherlands. 6University Utrecht, Copernicus Institute, Utrecht, Netherlands

Session 14. Leveraging Direct Flux Measurements Beyond Academia for Real-World Applications

Regional authorities and rural communities became aware of the hot-spot nature of greenhouse gas (GHG) emission from degraded peatlands. Drainage-based agriculture and forestry on peatlands are important contributors to overall anthropogenic emission from LULUCF sectors. Interestingly, peatland emission can vary spatially by up to 3 orders of magnitudes, both on the square meter and hectare scale, challenging policy development, policy implementation and national reporting. 

To foster co-learning, we created a regional GHG monitoring program in degraded peatlands in North-Netherlands. Water authorities, businesses, rural stakeholders, and conservation volunteers chose 16 dairy-grasslands and ran GHG measurements using automated chambers.  Our team improved flux quality by scaling fluxes to eddy covariance and soil carbon loss data. 

The regional GHG network revealed intermediate to high CO2 emission on drained peat soils. Drainage ditches contributed large CH4 and CO2 emission. Subsoil irrigation/drainage (PIS/OWD) and fluctuating ditch water levels (HAKLAM) failed to reduce CO2 emission. Effects were lacking probably because raised water tables remained below 50 cm from the surface during summer. In contrast,  decreased from 250 to 85 kg CO2 ha-1 day-1 when the water level approached the surface. Finally, emissions estimated by Tier 1 emission factors and Tier 2 national models mismatched the between-site and between-year variation found in the chamber-based estimated carbon budgets. Individual landowners, governmental representatives, and experts evaluated the measured peat soil emission using co-learning tools.

To conclude, our study showed that jointly-conducted GHG measurements creates common grounds for rural mitigation measures and improves well-informed acceptance of peatland rewetting.

 

371 Satellite-based ocean pCO2 estimates in the Central Mediterranean Sea and CO2 fluxes merging satellite and insitu data

Poster

Mattia Pecci1,2*, Fabrizio Anello3, Lorenzo De Silvestri4, Tatiana Di Iorio4, Daniela Meloni4, Francesco Monteleone3, Giandomenico Pace4, Salvatore Piacentino3, Damiano Sferlazzo1, Alcide di Sarra5

1Laboratory for Earth Observations and Analyses, ENEA, Lampedusa, Italy. 2Department of Information Engineering, Electronics and Telecommunications, La Sapienza University of Rome, Roma, Italy. 3Laboratory for Earth Observations and Analyses, ENEA, Palermo, Italy. 4Laboratory for Earth Observations and Analyses, ENEA, Roma, Italy. 5Laboratory for Earth Observations and Analyses, ENEA, Frascati, Italy

Session 10. Remote sensing of greenhouse gases from ground and space: Their application for carbon cycle studies, satellite and model validation and building MVS capacity

Insitu measurements of ocean CO2 partial pressure (pCO2), temperature and salinity are available at the Lampedusa Oceanographic Observatory (OO, 35.49°N, 12,47°E), in the central Mediterranean, starting from November 2021, together with ancillary quantities, including pH and chlorophyll concentration. The Lampedusa OO is in the ICOS labelling phase and the data used in this study are relative to the pre-ICOS period. The insitu pCO2 dataset was used to develop regression models using different sets of input variables, chosen among those that can be derived from satellite observations and related to physical and biological processes affecting pCO2. Two approaches have been used: traditional regression and machine learning, using the XGBoost model. When applied to satellite data, the best-performing multiple regression model, which uses temperature (through a linear and a quadratic term), chlorophyll, photosynthetically active radiation and wind speed as input, exhibited a mean bias of 4.4 µatm, an RMSD of 13.0 µatm, and an R2 of 0.94. In contrast, the machine learning approach, probably impacted by the limited training dataset, performed less effectively, with a mean bias of -1.4 µatm, an RMSD of 25.0 µatm, and an R2 of 0.76. pCO2 values estimated from satellite data have also been used to compute CO2 fluxes, using the Wanninkhof (2014) parameterization for the gas transfer velocity. The estimated fluxes show a fair agreement with the fluxes calculated from insitu data, with an R2 up to 0.75.

 

372 Evaluating greenhouse gas (GHG) emissions estimate robustness: Utilizing radon for atmospheric transport model uncertainty analysis

Poster

Dafina Kikaj1*, Alistair Manning2, Matt Rigby3, Peter Andrews2, Alexandre Danjou3, Edward Chung1, Grant Foster4, Angelina Wenger3, Tim Arnold1,5, Chris Rennick1, Simon O’Doherty3, Kieran Stanley3, Joseph Pitt3

1National Physical Laboratory, Teddington, United Kingdom. 2UK Met Office, Exeter, United Kingdom. 3School of Chemistry, University of Bristol, Bristol, United Kingdom. 4School of Environmental Sciences, University of East Anglia,, Norwich, United Kingdom. 5School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Atmospheric transport model (ATM) uncertainty continues to be a significant constraining factor in making confident top-down GHG emission estimates. Currently, the selection of data for inversion frameworks relies on empirical methods, often leading to biases in data filtering due to dependence on modelled meteorological variables. As a result, a substantial portion (about 40–75%) of continuous GHG observations remains unused in emission constraints.

To address this, we propose utilizing radon measurements, a naturally occurring radioactive noble gas with well-defined source and sink. Radon’s unique characteristics make it an ideal tracer to study the transport and mixing of air and thus has potential to act as an independent metric to evaluate ATM performance. A new approach involves utilising measured and modelled radon (calculated using the Met Office Numerical Atmospheric Modelling Environment (NAME) dispersion model and a radon flux map) to classify the ATM output uncertainty as either high (poor performance) or low (best performance). 

To assess the effectiveness of the radon selection approach, we conducted a comparative analysis on the UK methane (CH4) emissions sensitivity between two inverse methods, each employing different data filtering techniques. We subsequently applied the radon filtering approach to both inverse methods and quantify the differences. This will highlight the impact of filtering techniques and demonstrate the potential advantages of using radon as a tool for improving the accuracy of ATM performance assessments in GHG emission estimates.

 

373 Net Ecosystem Exchange in a Degraded Tropical Peatland: Can restoration of degraded tropical peatlands help Indonesia achieve its carbon neutral goals?

Oral

Charuni Jayasekara1*, Laura Graham2, Sopa Nindya2, Nafila Izazaya Idrus3, Sarah Treby1, Lindsay Hutley4, Peter Isaac5, Ian McHugh6, Catherine Leigh1, Jeff Shimeta1, Ewen Silvester7, Samantha Grover1

1RMIT University, Melbourne, Australia. 2Borneo Orangutan Survival Foundation, Borneo, Indonesia. 3University of Leuven, Leuven, Belgium. 4Charles Darwin University, Casuarina, Australia. 5Terrestrial Ecosystem Research Network, Queensland, Australia. 6University of Melbourne, Melbourne, Australia. 7La Trobe University, Melbourne, Australia

Session 13. In situ data for climate and other environmental services and policy support

Tropical peatlands are critical global carbon reservoirs, yet their degradation presents significant threat to global carbon balance. In Indonesia, degraded peatlands are a major source of CO2 emissions, and efforts to restore them are central to Indonesia's ambitious carbon neutrality goals. The carbon flux dynamics following restoration therefore requires ground data monitoring. This study investigates CO2 flux in a restoring tropical peatland in Indonesia using Eddy Covariance methods. High-frequency CO2 flux data spanning February 2020-September 2022 were processed using EddyPro and PyFluxPro software, while meteorological variables were gap-filled using satellite data. The peatland was a small net carbon source throughout the study period, while the monthly NEE did not significantly differ between each month. There was no significant difference in NEE between wet and dry seasons. The CO2 flux of the peatland did not correlate significantly with rainfall, likely due to higher and more controlled surface water levels maintained through this period due to adjacent canal-blocking activities and that it was a La Nina period (reduced dry season). Furthermore, the observed net CO2 source characteristics may be attributed to the fact that extensive areas of the hydrologically-linked peat dome remain unblocked, and the adjacent rewetting only began in 2020. We conclude that while the peatland is still a net CO2 source, it has the potential to convert to a net CO2 sink with continuous restoration efforts. We also note the importance of a landscape-approach to restoration efforts, and that long-term monitoring, which encompasses interannual trends and baseline levels, is essential.


374 The application of non-linearity calculations to greenhouse gas measurements made by cavity ring down spectroscopy.

Oral

Ruby Aklotsoe1*, Emmal Safi1, Tim Arnold1,2, Chris Rennick1, Tom Gardiner1

1National Physical Laboratory (NPL), Teddington, United Kingdom. 2University of Edinburgh, Edinburgh, United Kingdom

Session 17. Best Practices in the landscape of Research Infrastructures: Cooperation, Co-location and other lessons learned

Greenhouse gases (GHGs) are major sources of climate forcing. Since the first measurements, global networks have expanded to monitor large scale atmospheric trends. More recently there has been increasing emphasis on regional stations and networks (e.g. ICOS) to gather data on smaller scales needed for verifying international climate agreements. The development of these networks has been aided by progress in technology for higher frequency and lower maintenance measurements.

Building on previous work, the Greenhouse Gas Emissions Measurement and Modelling Advancement (GEMMA) aims at developing an emissions measurement ‘dashboard’ to monitor the UK’s progress to net zero by 2050 target. It uses existing and additional monitoring stations. 

GHG measurements were initially made using systems such as gas chromatographs (GC) flame ionisation detection (FID) for methane (CH4). Recently cavity ring down spectroscopy (CRDS) instrumentation has been developed and their precision and stability has led to rapid uptake in the use for GHG monitoring.  Here, we will show the application of non-linearity corrections used on CRDS instrumentation. We will use five NPL gravimetrically prepared synthetic reference materials which cover the atmospheric range of CH4, CO2, and nitrous oxide (N2O).

Using the CRDS measurements from in-house NPL reference materials to determine the non-linearity corrections, we demonstrate their impact by applying the corrections to results from a UK monitoring site. Additionally, we produce a comprehensive uncertainty budget associated with these corrections. Our results aim to highlight the potential uncertainty introduced by this correction and consider the necessity of applying the correction to the measurements.

 

375 Study of greenhouse gas fluxes and earth system feedbacks in the Horizon Europe project GreenFeedBack

Poster

Lise Lotte Sørensen1*, Ann Eileen Lennert2, Anne Sofie Lansøe1, Janne Rinne3, Ivan Mammarella4, Bruno Delille5, Anne Ojala3, Peter L. Langen1, Anna Rutgersson6, Jørgen Bendtsen7

1Aarhus University, Roskilde, Denmark. 2UiT, The Arcti University of Norway, Tromsø, Norway. 3LUKE, Helsinki, Finland. 4University of Helsinki, Helsinki, Finland. 5University of Liege, Liege, Belgium. 6Uppsala University, Uppsala, Sweden. 7University of Copenhagen, Copenhagen, Denmark

Session 6. Greenhouse gas fluxes at high latitudes and climate/human induced feedbacks

The Ambition of the presented project GreenFeedBack, is to enhance knowledge of the greenhouse gas dynamics in the ecosystems and link greenhouse gases in terrestrial, freshwater and marine ecosystems to provide a solid basis for estimation of regional and global climate feedback processes taking human pressure on ecosystems into account. In GreenFeedBack we study the key processes controlling the lifecycle and fluxes of greenhouse gases in sensitive terrestrial, freshwater, coastal and marine areas of which some are hypothesized to be tipping elements in the climate system. Thus, we focus on high latitude terrestrial and freshwater systems, marine shelves and ocean areas. We use data from the ICOS stations in Europe, The SOCAT database and the GIOS, GEM and SMEAR network in Greenland and Finland as well as data from new dedicated field and laboratory studies. The enhanced knowledge will be used to improve descriptions of the GHG processes for implementation in ecosystem models and ESMs. To ensure that human activities affecting the greenhouse gas cycles will be integrated as part of the full analysis the first step in GreenFeedBack has been to identify human impact on  the processes and variables relevant for driving the life cycles of the greenhouse gases in natural ecosystems. 

Here we present the GreenFeedBack project, the link between the greenhouse gases in the different high latitude ecosystems, and the human pressures affecting the greenhouse gas fluxes from the natural high latitude ecosystems.


376 Policy-driven mobile eddy covariance and chamber networks to monitor effectiveness of multiple emission mitigation measures in Frisian peat meadows.

Oral

Bart Kruijt1*, Reinder Nouta2, Laurent Bataille1, Wilma Jans1, Quint van Giersbergen3, Ralf Aben3, Wietse Franssen1, Jan Biermann1, Ruchita Ingle1, Ronald Hutjes1, Christian Fritz3, Niek Bosma2

1Wageningen University, Wageningen, Netherlands. 2Wetterskip Fryslan, Leeuwarden, Netherlands. 3Radboud University, Nijmegen, Netherlands

Session 14. Leveraging Direct Flux Measurements Beyond Academia for Real-World Applications

Managed grasslands on organic soils in the Netherlands, drained and used for dairy farming, are decomposing and hence emitting CO2 Dutch government has set tight goals to reduce these emissions while the relevant provinces and water authorities bear responsibility to achieve these.  There is substantial pressure to implement measures to both reduce emissions and preserve farming capacity, generally associated with elevating local ground water tables. Implementation is realised in various stages of experimentalness and scales, and it is urgent to test their effectiveness. To achieve this with direct flux measurements the challenges are both the small scale of and the large variety in measures and field conditions.

The province of Fryslân and the Frisian peat meadow programme have been proactively investing in a test scheme. Networks of flux measurement devices have been set up, including eddy covariance (EC) systems. Since mid-2021 four EC masts are deployed in pairs, rotating along sites and their associated controls for recurring one-week measurement periods. Each site is equipped with permanent observations of environmental variables as well as lateral imports and exports. The data enable both direct short-term assessment of mitigation measures versus controls and estimation of annual budgets, for which advanced machine-learning gap-fill models are developed. Results so far indicate that not all proposed measures are effective, where generally summer water tables need to be substantially elevated to reduce CO2 emissions. This monitoring network and its practical management consists a good example of how regional entities can invest in and execute direct verification themselves.


377 Influence of Local Changes in Atmospheric Boundary Layer Height and Thermal Stratification on Vertical CO2 Concentration Gradient in Lower Troposphere

Poster

Kateřina Komínková1,2*, Gabriela Vítková1, Roman Prokeš1,3, Kamil Láska2

1Global Change Research Institute, CAS, Brno, Czech Republic. 2Department of Geography, Fakulty of Sciences, Masaryk University, Brno, Czech Republic. 3RECETOX (Research Centre for Toxic Compounds in the Environment), Masaryk University, Brno, Czech Republic

Session 4. Processes involved in the greenhouse gas cycle in terrestrial ecosystems

The Vertical stability of the troposphere and the diurnal variation in the atmospheric boundary layer (ABL) height are significant factors influencing the diffusion of carbon dioxide CO2 and other greenhouse gasses (GHGs) in the environment. Both of these factors impact whether the CO2 concentration measurements at higher levels above ground remain significantly influenced by the local sources or the values are representative for a wider area.

To better understand CO2 dynamics in the atmosphere depending on these two factors at the Atmospheric station Křešín (which is the part of The National Atmospheric Observatory Košetice, Czech Republic), data from continuous measurements at two levels of 250 m height tall tower were used. Furthermore, the ABL height was included, which is measured by Vaisala CL51 ceilometer at the station using the BL-VIEW software for evaluation. To determine the vertical stability, the Pasquill Atmospheric Stability Classes were calculated based on the vertical temperature gradient measured at the tower. This stability classification system divides situations into seven stability classes, with three classes being stable, one normal and three unstable. 

Results of this study indicate that the magnitude of the difference in CO2 concentration between measurements at 10 and 250 m is strongly correlated with the ABL height. However, there is no clear dependence on the ABL height for the CO2 concentration measured at 250 m. Also the effect of vertical thermal stratification on concentrations at this level was not as significant as for measurements at the height of 10 m.

 

378 Towards global long-term multi-tracer data assimilation estimates of carbon fluxes

Oral

Joram Hooghiem1*, Auke van der Woude1, Anne-Wil van den Berg1, Remco de Kok1, Aleya Kaushik2,3, John Miller2, Ingrid Luijkx1, Wouter Peters1,4

1Meteorology and Air Quality, Wageningen University and Research, Wageningen, Netherlands. 2NOAA Global Monitoring Laboratory, Boulder, USA. 3Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, USA. 4Centre for isotope research, University of Groningen, Groningen, Netherlands

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Data assimilation of atmospheric CO2 is a powerful tool to provide global and regional carbon flux estimates.  Alongside CO2 measurements, observations of the isotope composition of CO2 ( both 13C and 14C) as well as atmospheric oxygen, O2, can be used to provide additional constraints on these estimates. Each of these additional tracers have their own connection to atmospheric CO2 through isotope or stoichiometric ratios in the underlying process leading to carbon fluxes. These couplings have been successfully exploited by passed studies. The atmospheric 13C/12C ratio is altered through different distinct isotope ratios of the underlying fluxes and has been used to quantify carbon uptake during droughts. Since 14C is radioactive, fossil emission are devoid of 14C, making it a good fossil fuel tracer against the modern day radiocarbon background. Then, the oxygen to nitrogen ratio has historically been used to constrain ocean fluxes, and more recently for fossil fuel emissions. The Long Window CarbonTracker Europe data assimilation system was designed to provide global and regional flux estimates at decadal to annual scales taking advantage of these records in a single multi-tracer data assimilation framework. We present the rationale of this system, along with results of atmospheric simulations with TM5 of these records and evaluate the performance of the data assimilation system against the observed global growth rate.

 

379 Lessons learned from the labelling phase of ICOS ecosystem stations

Poster

Simone Sabbatini1*, Giacomo Nicolini1, Eleonora Canfora1, Bert Gielen2, Carlo Trotta1, Maarten Op de Beeck2, Arne Iserbyt2, Dario Papale3

1CMCC Foundation - Euro-Mediterranean Center on Climate Change, Italy, Viterbo, Italy. 2University of Antwerp, Antwerp, Belgium. 3CNR IRET, Monterotondo, Italy

Session 17. Best Practices in the landscape of Research Infrastructures: Cooperation, Co-location and other lessons learned

Recent advancements in technology paved the way for extending eddy covariance (EC) measurements from local to global scales via the institution of networks of stations organised in research infrastructures (RIs). The scientific community benefits from RIs in terms of “better” data (e.g. spatial representativeness, inter-comparability), by which decision makers can rely on more accurate predictions. Participation of a station in a RI increases data quality thanks to the adherence to standardised protocols, at the cost of going through a preparatory phase (labelling), in which the station is guided by the facility appointed to ensure the compliance to the reference standards. For ICOS ecosystem stations, the labelling is coordinated by the ecosystem thematic centre (ETC) and it involves, among others, checking the location of EC measurements against topography, surface and wind characteristics, and analysing the statistical quality of the first data collected, with the purpose of maintaining quality across the network despite the heterogeneity of stations’ characteristics. This presentation highlights the key aspects that deserve thorough attention when establishing new EC measurements, based on the experience gained so far. What are the site issues more often under discussion? What are the checks that discard the most, affecting data continuity? The fastidious evaluation of surface peculiarities and a proper sensors’ setup are crucial, while the selection of the sensors’ location should be cross-checked by footprint analysis. Non-stationarity issues are the most frequent in data cleaning. Hence, efforts to reduce the presence of gaps due to technical issues are pivotal for data continuity.


380 MAGIC 2022-2023, a multi-measurement constraint on urban emissions

Poster

Charbel Abdallah1*, Thomas Lauvaux1, Lilian Joly2, Cyril Crevoisier3, Ke Che4, Nicolas Dumelié1, Bruno Grouiez1

1Groupe de Spectrométrie Moléculaire et Atmosphérique GSMA, Université de Reims-Champagne Ardenne, Reims, France. 2University of Reims Champagne-Ardenne, Reims, France. 3Laboratoire de Météorologie Dynamique (LMD/IPSL), CNRS, Ecole polytechnique, Palaiseau, France. 4Laboratoire des Sciences du Climat et de l’Environnement (LSCE), Gif-sur-Yvette, France

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Metropolitan areas are known to be anthropogenic “hot spots” of Greenhouse Gas (GHG) fluxes. To track their emission, mega-cities like Paris are currently being instrumented with dense atmospheric GHG networks, complementing the data collected by remote sensing satellites. To study medium-sized cities, where a large fraction of the global population lives, space-borne measurements often fail to quantify fossil fuel emissions since the atmospheric signatures are below the detection threshold of current instruments. For the past two years (2022 and 2023), the MAGIC campaign initiative led by CNRS and CNES (https://magic.aeris-data.fr) have been taking place in Reims, France, a city with a population of 300,000 inhabitants (207 hab./km2) located to the East of Paris (approx. 100 km away). During these two intensive measurement campaigns, a wide range of ground-based instruments have been deployed around the city to measure CO2 concentrations, in addition to instrumented balloons and aircrafts. The goal of these campaigns was to evaluate CO2 emissions from the area and to assess the detection capabilities of current satellite instruments. 

In our study, we simulated the atmospheric CO2 mixing ratios using the Weather Research Forecast model coupled to a chemistry transport model (WRF-Chem) at 1-km horizontal resolution. To quantify the real fluxes, we set-up an inversion system that assimilates both in-situ and in-flight observations based on their spatial-temporal footprints, as modelled by a Lagrangian Particle Dispersion Model. Here, we present the inversion-optimized fluxes and compare them to the emission inventories of the city, along with a model-to-observation validation.

 

381 Exploring acidification dynamics in the Southern Adriatic: Insights from high frequency pCO2 and pH data at the E2M3A observatory

Poster

Carlotta Dentico1,2*, Michele Giani2, Giuseppe Civitarese2, Giuseppe Siena2, Martina Kralj2, Angelo Rubino1, Vanessa Cardin2

1Department of Environmental Sciences, Informatics and Statistics, DAIS – University Ca’ Foscari of Venice, Mestre, Italy. 2National Institute of Oceanography and Applied Geophysics - OGS, Sgonico (TS), Italy

Session 7. Carbon Cycling along the Land Ocean Aquatic Continuum

An increasing amount of anthropogenic CO2 has been absorbed by the world's oceans, leading to a process commonly known as Ocean Acidification. It has been recognised that the regulation of oceanic CO2 uptake is controlled by the overturning circulation. Accordingly, the site of dense water in the southern Adriatic Sea could play an important role in CO2 sequestration and contribute to the acidification of the eastern Mediterranean. In this contribution we analyse high-frequency pCO2 and pH data from an automatic sampling system set up on the surface buoy of the EMSO-E2M3A regional facility. E2M3A is moored in the centre of the southern Adriatic Pit  and has been collecting pCO2 and pH data since 2015. We observe a pronounced seasonal variability in pCO2 and pH which highlights their correlation with temperature variations. High-frequency time series of thermohaline data measured at E2M3A and Argo floats profile are also presented. These data show that the region has undergone pronounced physical changes (increase of temperature and salinity) leading to an increased vertical mixing. Warming and salinification of the SAP could lead to significant changes in the carbonate system such as a decrease in pH and an increase in pCO2 throughout the water column as shown from bottle samples data from oceanographic cruises collected in the region between 2008 and 2023. Our results demonstrate the importance of an integrated oceanographic approach that combines fixed-point observations with hydrographic surveys to comprehensively investigate the response of the Adriatic Sea to climate change.

 

382 CO2 source identification of two nearby flux towers in the city centre of Basel, Switzerland

Poster

Christian Feigenwinter, Stavros Stagagis*, Roland Vogt, Markus Kalberer

University of Basel, Basel, Switzerland

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

The CO2 sources of two nearby (2 km apart) flux towers in the city center of Basel, Switzerland, are analyzed with respect to traffic frequencies, heating type of buildings, vegetation and human metabolism for a period from 2009 up to date. Main differences between the two locations can be attributed to a) different traffic frequencies and b) different types of building heating. It is shown that the development and progression of district heating during the last years significantly reduces the CO2 emissions at one station, while in the footprint of the other station, district heating was already established 15 years ago and no trend in CO2 emissions could be observed. We also show, that wind direction patterns significantly modify the contribution of traffic to the measured CO2 fluxes. As a conclusion we postulate to weight flux footprint contributions rather by source strengths than by land use/land cover classes.


383 Assessment of float pH data quality control methods from the coupling of two observational infrastructures: A case study in the subpolar northwest Atlantic Ocean

Oral

Cathy Wimart-Rousseau1,2*, Tobias Steinhoff1, Birgit Klein3, Henry Bittig4, Arne Körtzinger1,5

1GEOMAR Helmholtz Centre for Ocean Research Kiel, 24148 Kiel, Germany, Kiel, Germany. 2National Oceanography Centre (NOC) Southampton, United Kingdom, Southampton, United Kingdom. 3Federal Maritime and Hydrographic Agency (BSH), 20359 Hamburg, Germany, Hamburg, Germany. 4Marine Chemistry, Leibniz Institute for Baltic Sea Research Warnemuende (IOW), Seestrasse 15, 18119 Rostock, Germany, Rostock, Germany. 5Faculty of Mathematics and Natural Sciences, Christian-Albrechts-Universität zu Kiel, 24118 Kiel, Germany, Kiel, Germany

Session 3. Cross-domain technological development: autonomous vehicles, sensor miniaturisation, low-cost sensors and labour-intense approaches

Autonomous measurement platforms such as Biogeochemical-Argo (BGC-Argo) floats achieve continuous and independent access to the marine CO2 system since a pH sensor has become available that is principally suitable for use on profiling platforms. This opens the possibility to detect variability and long-term changes in the interior ocean inorganic carbon storage and to quantify the ocean sink for atmospheric CO2. From a sensor perspective, the marine CO2 system is a particularly challenging case. This puts a high emphasis on the quality control of float-based pH measurements. 

By applying current standardized adjustment routines to pH measurements from a pH/O2 float pilot array in the subpolar North Atlantic Ocean, we assess the uncertainties and lack of objective criteria associated with the standardized routines. In our analysis, an independent assessment of the adjusted float pH data quality is presented based on crossover comparisons against discrete hydrocasts measurements and underway Ship-of-Opportunity (SOOP) pH observations. Our results point to the possibility of unacceptably high pH biases in the surface ocean which call for an additional independent reference in the surface ocean in regions with deep winter mixing.

 

We show evidence that a closer link between the BGC-Argo and SOOP observatories would be mutually beneficial to both networks and could potentially serve the aforementioned purpose in certain regions. Given its large synergy potential, we, therefore, propose a systematic coupling of the two observing infrastructures as they allow a better understanding of the complete water column's physical and biogeochemical variations.

 

384 Automated transparent chamber measurements of carbon monoxide fluxes from an intensively used grassland on drained peat in the Netherlands

Poster

Ralf Aben1*, Stefan Weideveld1, Guido Bijlsma1,2, Christian Fritz1

1Radboud University, Nijmegen, Netherlands. 2B-WARE Research Centre, Nijmegen, Netherlands

Session 2. Exchange of reactive gases and aerosols between the land surface and the atmosphere in natural and managed ecosystems

Carbon monoxide (CO) forms an indirect greenhouse gas with a cumulative radiative forcing larger than that of nitrous oxide. It achieves this effect by competing for hydroxyl (OH) radicals that break down gases such as methane and ozone in the atmosphere. Incomplete combustion of fuel sources (e.g. fossil fuels, forest fires) is the major source of CO, while conversion of CO to CO2 via reacting with OH in the atmosphere is the major removal pathway. However, CO can also be produced and removed by organisms in ecosystems, including those managed for agricultural use. Not much is known about the size of CO fluxes from these systems, their temporal dynamics, and controlling mechanisms. Here, we present data of two years of measurements with automated transparent chambers in an intensively managed grassland on drained peat in the Netherlands. At the conference, we will present annual average emission estimates, diurnal and seasonal variation patterns, and an overview of the most important drivers that include effects of management practices such as mowing and fertilization in addition to environmental conditions. Finally, we will present the potential of machine learning algorithms (Random Forest, XGBoost) for gapfilling CO fluxes.


385 Characterisation of δ13CH4 source signatures from methane sources in Germany with two different sampling strategies

Poster

Julia Wietzel*, Moritz Pfau, Virctoria Hahn, Maren Zeleny, Till Gonser, Ilka Sauer, Piotr Korben, Antje Hoheisel, Martina Schmidt

Instiute of Environmental Physics, Heidelberg, Germany

Session 1. Isotopes and other tracers for studies of methane sources and sinks

Determining the carbon isotopic signature (δ¹³CH₄) of different methane sources is an important tool for understanding the methane cycle and focusing on the contribution of individual sources. Changes in the atmospheric CH4 isotope composition can be expected in the long term records, particularly as a result of the ongoing energy transition in Europe. 

In this study, both direct methane source samples and samples collected in the CH4 emission plumes  were measured with a Cavity Ring-Down Spectrometer (CRDS) G2201-i (Picarro, Inc., Santa Clara, CA) to determine their isotopic δ¹³CH₄ composition. In order to obtain accurate measurement results, it is essential to characterise the instrument accurately, taking into account the possible influence of other gases like H2O and C2H6. The isotopic signature of samples collected in the CH4 plume is determined using the Keeling approach and the York fitting method.

Samples were collected from 10 biogas plants, a wastewater treatment plant, the sewage system and a cowshed. Furthermore, the isotopic 13CH4 source signature from the Heidelberg natural gas distribution network were analysed between 2017 and 2024.

 

386 Ammonia deposition evaluation at the ICOS Loobos site

Oral

Arjan Hensen1*, Jun Zhang1, Pascal Wintjen1, Harmen Manson1, Kevin Felter2, Rene van der Hoff3, Susanna Jonker2, Ewout Melman2, Margreet van Zanten2, Marty Haaima3, Stijn Berkhout2, Mark Eijkelboom2, Julie Fry4, Michiel van der molen4

1TNO, Petten, Netherlands. 2RIVM, Bilthoven, Netherlands. 3rivm, Bilthoven, Netherlands. 4WUR, Wageningen, Netherlands

Session 2. Exchange of reactive gases and aerosols between the land surface and the atmosphere in natural and managed ecosystems

The Loobos ICOS level 2 ecosystem site is in the heart of the Netherlands and downwind of a major agricultural production area known as the Geldersche vallei. Since autumn  2023 ammonia deposition measurements were added to the station data set as a campaign. The role of ammonia for the total nitrogen deposition is in the order of  60 %  in this area. This was estimated based on data obtained in Speuld forest tower (about 15km north of Loobos) in the episode 1985-2010 after which measurements stopped at Speuld. Now NH3 measurements are back and both the scientific interest as well as socio economic relevance is high.We will show how that data is obtained, discuss the issues that make NH3 observations different from the CO2/ H2O exchange measurements  and show the levels of the deposition velocity and canopy compensation point that we have derived thusfar. We will also show the impact of the nearby agricultural area on the data and thus on the deposition at the Veluwe Natura 2000 area.

 

387 Mixing layer heights in ICOS Pilot Cities

Poster

Christopher Claus Holst1*, Changxing Lan1, William Morrison2, Betty Molinier3, Maxime Hervo4, Natascha Kljun3, Matthias Mauder5,1

1Karlsruhe Institute of Technology, Karlsruhe, Germany. 2University of Freiburg, Freiburg, Germany. 3Lund University, Lund, Sweden. 4Federal Office of Meteorology and Climatology MeteoSwiss, Zurich, Switzerland. 5Dresden University of Technology, Dresden, Germany

Session 11. Quantification of urban greenhouse gas emissions - from novel monitoring to source identification

Quantifying emissions based on in-situ flux measurements requires correct footprint calculations to link the fluxes measured at certain heights to their emission sources on the ground. In urban environments, heterogeneity of mechanical and thermal forcings is generally large across length-, time- and magnitude-scales. To facilitate the estimation of uncertainties within the footprint calculation, we calculated mixing layer heights using different methods, based on Doppler Wind Lidar and Radiometer Temperature profile measurements from Zürich, Munich, and Paris. We used observations of vertical and horizontal wind, temperature, and aerosol backscatter profiles to compile several different height estimates with a focus on the question, what dynamic obstacle an air-parcel might encounter first when released at the ground. Interestingly, the resulting height estimates differ greatly between different methods. We present and discuss the methods, demonstrate the differences, and suggest how to interpret these differences for applications in models and other observational techniques, such as footprint analysis or flask sampling methods.


388 Carbon fluxes in marginal ice zone

Poster

Erik J. SCHAFFERNICHT1*, Lichuan Wu1, Peter Langen2, Rayanne Vitali2, Minchao Wu1, Anna Rutgersson1

1Uppsala University, Uppsala, Sweden. 2Aarhus University, Rosklide, Denmark

Session 7. Carbon Cycling along the Land Ocean Aquatic Continuum

Carbon fluxes in the marginal ice zone (MIZ) are important to better understand the Earth’s carbon cycle, especially in the high latitude regions. This work presents the spatiotemporal distribution of the carbon fluxes in the marginal ice zone based on global numerical experiments using Nucleus for European Modelling of the Ocean (NEMO) with ORCA2. 

To explore and assess the suitability of different numerical net CO2 air-sea flux parameterizations, we performed a control, a ‘marginal ice zone’-off (MIZ-off) , a linear/non-linear carbon flux experiment. Each of them simulating 40 years with the respective parameterizations switched on at year 21. 

Our results show both, the global and the pole-related spatial distribution of the carbon fluxes. They also show the seasonal flux distribution resolved per month. Considerable variability in both, the spatial and temporal distribution is found. 

 

389 Integration of ground and satellite datasets for the improvement of accessibility to EO resources: the OEMC project

Poster

Simone Sabbatini1*, Leandro Parente2, Dario Papale3, Tom Hengl2, Martin Herold4, Luca Brocca5, Gregory Duveiller6, Igor Milosavljevic7, Steffen Fritz8

1CMCC Foundation - Euro-Mediterranean Center on Climate Change, Italy, Viterbo, Italy. 2OpenGeoHub, Wageningen, Netherlands. 3CNR IRET, Monterotondo, Italy. 4GFZ German Research Centre for Geosciences, Potsdam, Germany. 5CNR IRPI, Perugia, Italy. 6Max Planck Institute for Biogeochemistry, Jena, Germany. 7Association of Balkan Eco - Innovation, Novi Sad, Serbia. 8International Institute for Applied Systems Analysis, Laxenburg, Austria

Session 13. In situ data for climate and other environmental services and policy support

The Open-Earth-Monitor Cyberinfrastructure (OEMC) project, funded by the European Union, aims at designing tools for increasing the accessibility of datasets in the earth observation (EO) sector. By combining in-situ measurements with space-borne datasets, the OEMC project is developing processing facilities and cybernetic resources for the interoperability and visualisation of related outcomes. The datasets used and produced must have an open licence (e.g. CC-BY) and follow the principles of the FAIRness standards. They have been organised in three Tiers, depending on their relevance, representativeness, spatial scale and other characteristics. More than 30 use cases have been identified, which represent the stakeholder interest and which are organised in monitors for specific goals. ICOS datasets included in FLUXNET are one of the eight categories of in-situ input supporting the project use cases and monitors. In addition to facilitating the users experience, the project is expected to benefit the scientific community and the whole society by enlarging the measurements coverage, reaching new and more accurate outcomes, increasing visibility, augmenting the capabilities of important entities such as the Intergovernmental Panel on Climate Change (IPCC), United Nations Framework Convention on Climate Change (UNFCCC), and other European and global bodies. We present here the OEMC project main characteristics, first outcomes, and in-situ contributions.


390 The Copernicus Atmosphere Monitoring Service (CAMS) global greenhouse gases forecasts and near-real-time analysis

Poster

N'Dri Ernest Koffi1*, Anna Agusti-Panareda2, Luca Cantarello1, Bavo Langerock3, Ramonet Ramonet4, Nicolas Bousserez1, Sebastien Massart2, Panagiotis Kountouris1, Aura Lupascu1, Mihai Alexe1, Zak Kipling2, Richard Engelen1, Johannes Flemming1, Antje Inness2, Henk Eskes5, Auke Visser1, Mark Parrington1, Souhail Boussetta2, Joe McNorton2, Margarita Choulga2, Philippe Peylin4, Vladislav Bastrikov4, Fabienne Maignan4, Elodie Salomon4, Catherine Prigent6, Roberto Ribas2, Christopher Kelly2, Miha Razinger2, Luke Jones2, Andrew Barr7, Michael Buchwitz8, Tobias Borsdorff7, Cyril Crevoisier9, Nicolas Meilhac9, Stefan Noel8, Maximilian Reuter8, Frédéric Chevallier4, Arjo Segers10, Thorsten Warneke11, Vincent-Henri Puech1

1ECMWF, Bonn, Germany. 2ECMWF, Reading, United Kingdom. 3Royal Belgian Institute for Space Aeronomy, Avenue Circulaire 3, 1180, Uccle, Belgium. 4Laboratoire des Sciences du Climat et de l’Environnement (LSCE-IPSL), CEA-CNRS-UVSQ, Université Paris-Saclay, 20 91191, Gif-sur-Yvette, France. 5Royal Netherlands Meteorological Institute, Utrechtseweg 297, NL-3731 GA, De Bilt, Netherlands. 6Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères, Observatoire de Paris, CNRS, Paris, France. 7SRON Netherlands Institute for Space Research, Utrecht, Netherlands. 8Institute of Environmental Physics (IUP), University of Bremen, 28334, Bremen, Germany. 9Laboratoire de Météorologie Dynamique (LMD/IPSL), CNRS, Ecole polytechnique, 91128, Palaiseau Cedex, France. 10TNO, Department of Climate, Air and Sustainability, Utrecht, Netherlands. 11Institute of Environmental Physics, University of Bremen, Otto-Hahn-Allee 1, 28359, Bremen, Germany

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

CAMS produces global daily forecasts and near real-time analysis of concentrations of CO2 and CH4. The procedure combines model data and satellite retrievals to create a complete and consistent dataset using ECMWF’s IFS model and a 4D-Var assimilation system. The current forecast and analysis system centered on the IFS model contains the land surface model ECLand which includes Farquhar’s photosynthesis model and a simple online wetland model for the simulations of CO2 and CH4 biogenic fluxes, respectively. Moreover, ocean flux, biomass burning, and anthropogenic emissions are prescribed for both CO2 and CH4. The atmospheric CH4 sink is described using monthly mean climatological data pertinent to the CH4 chemical loss rate in the atmosphere. Furthermore, data relevant to CH4 sinks from the soil, and sources from termites and wild animals are also considered. To limit a potential model drift over time, optimized concentrations from CAMS global flux inversions are used as initial values at the start of each IFS system upgrade. To enhance the accuracy of the analysis, a new background error matrix has been created for each species using an ensemble data assimilation method. The CAMS analysis (~25km) is produced with a time lag of 4 days due to the latency of satellite retrievals. The high-resolution forecast (~9km) is run separately a few hours behind real-time and relies on the analysis as initial conditions for atmospheric CO2 and CH4.  We will demonstrate how the latest developments in the model and assimilation system have improved the analysis and forecast by comparing model simulations with independent observations. 

 

391 Time of trend detection above natural variability in cases of ocean alkalinity enhancement along the EU coastline

Poster

Sandy Avrutin*, Andreas Oschlies, Tronje Kemena, David Keller

GEOMAR, Kiel, Germany

Session 8. Enhancing the ocean carbon sink: the science, verification, and governance of marine-based carbon dioxide removal (mCDR)

Limiting global warming to 1.5 or 2°C now requires a portfolio of carbon dioxide removal (CDR) strategies. Ocean alkalinity enhancement (OAE) is a form of marine CDR that shows promise of being scalable and effective in the long-term. However, for it to be implemented on a large scale, there must be robust MRV to ensure responsible deployment and inform future OAE efforts. This can be done with model studies and observations, and because of financial and practical considerations, it is important to understand what can and should be observed in-situ before deploying sensors. Using models to determine the amount of data to detect a trend in biogeochemical properties above natural variability is not new (see e.g. Henson et al. 2010 and 2016, McKinley et al., 2016). However, there has been little consideration on whether this is altered in the case of OAE, where a significant perturbation to the carbonate chemistry on a localized scale can be expected. Here, we use the method of Henson et al. (2016) to assess the time of trend detection for biogeochemical properties such as DIC, alkalinity and pH in the case of continuous OAE deployment along the parts of the European coastline exposed to the North Sea/Atlantic Ocean. This is compared to a baseline run with no OAE, to understand whether the implementation of OAE impacts the length of observations necessary to detect its own influence. We do this with background emissions following SSPs 126 and 370 from 2015 until 2100.


392 Traceability of δ13C(CH4) and δ2H(CH4) measurements from a UK tall tower site

Poster

Emmal Safi1*, Chris Rennick1, Lowry Dave2, Rebecca Fisher2, Mathias Lanoiselle2, Carina van der Veen3, Thomas Röckmann3, Jacoline van Es3, Bibhasvata Dasgupta3, Tim Arnold1,4

1National Physical Laboratory, Teddington, United Kingdom. 2Royal Holloway, University of London, Egham, United Kingdom. 3University of Utrecht, Utrecht, Netherlands. 4University of Edinburgh, Edinburgh, United Kingdom

Session 1. Isotopes and other tracers for studies of methane sources and sinks

To achieve comparability between methane (CH4) isotope ratio data sets, measurements must be reported on an agreed scale. The reference materials should be traceable to the international standards (Vienna Peedee Belemnite (VPDB) for δ13C and Vienna Standard Mean Ocean Water (VSMOW) for δ2H).

The majority of atmospheric δ13C(CH4) and δ2H(CH4) measurements have been carried out on weekly collected flask samples which are analysed via IRMS in the laboratory. The latest global inter-comparison covered only IRMS measurements and found interlaboratory discrepancies due to different calibration approaches1. Optical instruments are capable of autonomous operation but harmonisation of measurements for network compatible datasets is even further limited due availability of suitable reference materials and diverse methodologies for in situ calibration.

Standardised methodologies to enhance comparability of optical measurements of atmospheric δ13C(CH4) and δ2H(CH4) are being developed in an ongoing EURAMET project. We present analyses of δ13C(CH4) and δ2H(CH4) from samples collected at a UK tall tower site via a CH4 preconcentrator coupled to a laser spectrometer2,3. We show how the system is calibrated using synthetic and whole-air standards (with assigned isotope ratio values traceable to VPDB and VSMOW scales). We describe the development of our long-term strategy for making traceable measurements that are compatible with other European laboratories.

[1] Umezawa, T., et al. (2018). Atmos. Meas. Tech., 11(2), 1207-1231, doi: 10.5194/amt-11-1207-2018

[3] Rennick, C., et al. (2021).  Anal. Chem., 93, 10141-10151, doi: 10.1021/acs.analchem.1c01103

[4] Safi, E., et al. (2024).  Anal. Chem., doi: 10.1021/acs.analchem.3c04891


393 Atmospheric monitoring of the CO2 anthropogenic and biogenic fluxes, at European and national scales, based on the assimilation of surface and satellite observations.

Oral

Elise Potier1*, Audrey Fortems Cheiney1, Antoine Berchet2, Isabelle Pison2, Robin Plauchu2, Julia Marshall3, Hugo Denier van der Gon4, Frederic Chevallier2, Philippe Peylin2, Vladislav Bastrikov1, Grégoire Broquet2

1Science Partners, Paris, France. 2LSCE, Gif sur Yvette, France. 3DLR, Oberpfaffenhofen-Wessling, Germany. 4TNO, Utrecht, Netherlands

Session 9. Combining data and models to improve estimates of regional to global GHG budgets and trends

Atmospheric inversion will be the key element of the operational global and multi-scale Copernicus CO2 monitoring service, that will support national greenhouse gas emission reporting and reduction policies. The CO2MVS inversion framework should strongly rely on satellite observations from the future CO2M missions. In the meantime, there is a need to prepare this service with the existing observation networks. This presentation summarizes results from CO2 inversions at the scale of Europe and France carried out across several European projects. They rely on the coupling between the CHIMERE transport model at 10 to 50 km resolution and its adjoint to the variational mode of the Community Inversion Framework (CIF). The inversions assimilate, separately or jointly, observations of total column CO2 mixing ratios from NASA's OCO-2 and surface observations of COmixing ratios. The analyses reveal i) some issues and difficulties to control the anthropogenic emissions at the national scale when using the current observation network, ii) some inconsistencies between the results obtained from the assimilation of satellite vs. surface observations at the annual to monthly scale, and iii) the challenge of deriving robust estimates of the land terrestrial fluxes at the annual scale. However, they also demonstrate some sensible and consistent patterns in the estimates of the ecosystem fluxes over long periods of time and when testing the use of different a priori flux estimates for the terrestrial ecosystem fluxes (ORCHIDEE, VPRM, CTESSEL). The assimilation of surface observations currently appears to be more robust than that of the satellite data.


394 Inorganic carbon transported into the Gulf of Trieste by rivers draining karstic areas

Poster

Martina Kralj1, Vincenzo Alessandro Laudicella1*, Matteo Bazzaro1, Federica Relitti1, Simona Retelletti Brogi1, Cinzia De Vittor1, Michele Giani1, Nives Ogrinc2, Bor Krajnc2, Stefano Covelli3, Elena Pavoni3, Nessim Douss1

1National Institute of Oceanography and Applied Geophysics- OGS, Trieste, Italy. 2Jožef Stefan Institute, Ljubljana, Slovenia. 3Department of Mathematics, Informatics and Geosciences, Trieste University, Trieste, Italy

Session 7. Carbon Cycling along the Land Ocean Aquatic Continuum

Rivers act as important sources of carbon dioxide (CO2) to the atmosphere, playing an important role in changing the estuarine carbonate system. Rivers and underwater springs draining carbonate watersheds deliver freshwater into the Gulf of Trieste (GoT) and contribute significantly to increasing the alkalinity in coastal waters. 

The CO2 system of the Isonzo (at the mouth) and the subterranean Timavo (at the mouth and at one underwater spring) Rivers flowing into the GoT was sampled monthly between September 2021 and December 2022 to understand the dynamics of the carbonate system (total alkalinity, pH, calcium, magnesium, strontium and δ¹³C -DIC) at the end of the catchment and to estimate the input of alkalinity and bicarbonate into the marine system. 

Both rivers were characterized by high mean alkalinities (3056-4632 µmol kg-1), with higher concentrations in the Timavo system, which also showed greater weathering of calcium carbonates than the Isonzo, where the dissolution of dolomites increases the Mg:Ca molar ratio (Timavo spring 0.08±0.02, Timavo River: 0.17±0.04, Isonzo River: 0.29±0.03).

Timavo spring and River were highly enriched in pCO2 (24182±7800 µatm and 12297±5433 µatm, respectively) and δ¹³C-DIC depleted (-13.2±0.4‰ and -11.5±0.8 ‰, respectively) due to limited degassing and degradative processes occurring in the subterranean course. Conversely lower pCO2 (2299±1624 µatm) and higher δ¹³C-DIC (-8.6±0.8‰) values were observed in the Isonzo River. Both rivers act as a CO2 source to the atmosphere, with a higher contribution of the Isonzo River compared to the Timavo subterranean system.

 

395 Integrating Data into Urban Climate Governance: Interdisciplinary Approaches Through Collaborative Strategies

Poster

Barbara Dias Carneiro*, Miranda Schreurs, Ana Maria Isidoro Losada, Kaayin Kee

TUM, Munich, Germany

Session 17. Best Practices in the landscape of Research Infrastructures: Cooperation, Co-location and other lessons learned

The research presented in this paper underscores the importance of interdisciplinary collaboration, particularly within the science-policy interface, in addressing the challenges of integrating data into urban climate governance. The study, focused on the experiences of Paris, Munich, and Zurich, highlights the intricate multi-level governance structures in these cities and the interactions between stakeholders involved in shaping, sharing and implementing data into climate strategies. By employing a combination of interviews, workshops and document analysis, the research not only illuminates the increasing complexity of interactions between different stakeholders but also accentuates the importance for collaboration within the science-policy field. These collaborations ext