TY - JOUR T1 - Forecasting global atmospheric CO2 A1 - Agustí-Panareda, A. A1 - Massart, S. A1 - Chevallier, F. A1 - Boussetta, S. A1 - Balsamo, G. A1 - Beljaars, A. A1 - Ciais, P. A1 - Deutscher, N. M. A1 - Engelen, R. A1 - Jones, L. A1 - Kivi, R. A1 - Paris, J.-D. A1 - Peuch, V.-H. A1 - Sherlock, V. A1 - Vermeulen, A. T. A1 - Wennberg, P. O. A1 - Wunch, D. Y1 - 2014/05// JF - Atmospheric Chemistry and Physics Discussions VL - 14 IS - 9 SP - 13909 EP - 13962 DO - 10.5194/acpd-14-13909-2014 UR - http://www.atmos-chem-phys-discuss.net/14/13909/2014/ N2 - A new global atmospheric carbon dioxide (CO2) real-time forecast is now available as part of the pre-operational Monitoring of Atmospheric Composition and Climate – Interim Implementation (MACC-II) service using the infrastructure of the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS). One of the strengths of the CO2 forecasting system is that the land surface, including vegetation CO2 fluxes, is modelled online within the IFS. Other CO2 fluxes are prescribed from inventories and from off-line statistical and physical models. The CO2 forecast also benefits from the transport modelling from a state-of-the-art numerical weather prediction (NWP) system initialized daily with a wealth of meteorological observations. This paper describes the capability of the forecast in modelling the variability of CO2 on different temporal and spatial scales compared to observations. The modulation of the amplitude of the CO2 diurnal cycle by near-surface winds and boundary layer height is generally well represented in the forecast. The CO2 forecast also has high skill in simulating day-to-day synoptic variability. In the atmospheric boundary layer, this skill is significantly enhanced by modelling the day-to-day variability of the CO2 fluxes from vegetation compared to using equivalent monthly mean fluxes with a diurnal cycle. However, biases in the modelled CO2 fluxes also lead to accumulating errors in the CO2 forecast. These biases vary with season with an underestimation of the amplitude of the seasonal cycle both for the CO2 fluxes compared to total optimized fluxes and the atmospheric CO2 compared to observations. The largest biases in the atmospheric CO2 forecast are found in spring, corresponding to the onset of the growing season in the Northern Hemisphere. In the future, the forecast will be re-initialized regularly with atmospheric CO2 analyses based on the assimilation of CO2 satellite retrievals, as they become available in near-real time. In this way, the accumulation of errors in the atmospheric CO2 forecast will be reduced. Improvements in the CO2 forecast are also expected with the continuous developments in the operational IFS. ER - TY - JOUR T1 - Evolution of the nocturnal decoupled layer in a pine forest canopy A1 - Alekseychik, P. A1 - Mammarella, I. A1 - Launiainen, S. A1 - Rannik, Ü. A1 - Vesala, T. Y1 - 2013/06// KW - Carbon dioxide KW - Eddy-covariance KW - Nighttime problem KW - Subcanopy flow KW - Thermal decoupling JF - Agricultural and Forest Meteorology VL - 174-175 SP - 15 EP - 27 SN - 0168-1923 DO - 10.1016/j.agrformet.2013.01.011 UR - http://linkinghub.elsevier.com/retrieve/pii/S0168192313000257 N2 - Estimates of the biosphere-atmosphere exchange rates measured using the eddy-covariance (EC) technique are often found to deviate from their expected values. The mismatch is caused by a variety of poorly known and quantified processes, such as storage, subcanopy advection, drainage flows and other non-turbulent air motions, which become particularly important at nighttime. In many forest sites, clear and calm nights favor the generation of the phenomenon commonly known as decoupling, when the above- and sub-canopy air layers relation can be significantly weakened. The data obtained above and within a Scots pine forest at the SMEAR II-station in Hyytiälä, southern Finland, were used to study the decoupling conditions. Certain features of the site (sloping terrain, tall pine trees, sharp separation of the canopy and trunk spaces, insignificant undergrowth) facilitate and augment the development of decoupling conditions. As a result, the EC measurement data contain a multitude of severe CO2 flux loss cases biasing the carbon balance estimates. The results concerning decoupling cases are presented and the mechanisms of generation and alteration of the decoupling conditions are discussed. Different regimes of decoupling were detected based on the vertical profile of the mean wind direction. Decoupling was defined as the periods when the wind directional shear in the canopy or trunk space exceeded predefined thresholds. In at least 18.6% of all nighttime periods, decoupling conditions were identifiable by high wind directional shear in the canopy sublayer.A close relation between the stability estimated by the Richardson number and the decoupled layer thickness was observed. Decoupling interface tended to move to a higher level as stability increased. Drainage flow was detected near the ground in the cases of maximum decoupled layer thickness. Finally, the difference was drawn between the drainage flow and the decoupled layer based on observational evidence. © 2013 Elsevier B.V. ER - TY - JOUR T1 - Inverse modelling of CH4 emissions for 2010–2011 using different satellite retrieval products from GOSAT and SCIAMACHY A1 - Alexe, M. A1 - Bergamaschi, P. A1 - Segers, A. A1 - Detmers, R. A1 - Butz, A. A1 - Hasekamp, O. A1 - Guerlet, S. A1 - Parker, R. A1 - Boesch, H. A1 - Frankenberg, C. A1 - Scheepmaker, R. A. A1 - Dlugokencky, E. A1 - Sweeney, C. A1 - Wofsy, S. C. A1 - Kort, E. A. Y1 - 2015/01// JF - Atmospheric Chemistry and Physics VL - 15 IS - 1 SP - 113 EP - 133 DO - 10.5194/acp-15-113-2015 UR - http://www.atmos-chem-phys.net/15/113/2015/ N2 - At the beginning of 2009 new space-borne observations of dry-air column-averaged mole fractions of atmospheric methane (XCH4) became available from the Thermal And Near infrared Sensor for carbon Observations–Fourier Transform Spectrometer (TANSO-FTS) instrument on board the Greenhouse Gases Observing SATellite (GOSAT). Until April 2012 concurrent {methane (CH4) retrievals} were provided by the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) instrument on board the ENVironmental SATellite (ENVISAT). The GOSAT and SCIAMACHY XCH4 retrievals can be compared during the period of overlap. We estimate monthly average CH4 emissions between January 2010 and December 2011, using the TM5-4DVAR inverse modelling system. In addition to satellite data, high-accuracy measurements from the Cooperative Air Sampling Network of the National Oceanic and Atmospheric Administration Earth System Research Laboratory (NOAA ESRL) are used, providing strong constraints on the remote surface atmosphere. We discuss five inversion scenarios that make use of different GOSAT and SCIAMACHY XCH4 retrieval products, including two sets of GOSAT proxy retrievals processed independently by the Netherlands Institute for Space Research (SRON)/Karlsruhe Institute of Technology (KIT), and the University of Leicester (UL), and the RemoTeC "Full-Physics" (FP) XCH4 retrievals available from SRON/KIT. The GOSAT-based inversions show significant reductions in the root mean square (rms) difference between retrieved and modelled XCH4, and require much smaller bias corrections compared to the inversion using SCIAMACHY retrievals, reflecting the higher precision and relative accuracy of the GOSAT XCH4. Despite the large differences between the GOSAT and SCIAMACHY retrievals, 2-year average emission maps show overall good agreement among all satellite-based inversions, with consistent flux adjustment patterns, particularly across equatorial Africa and North America. Over North America, the satellite inversions result in a significant redistribution of CH4 emissions from North-East to South-Central United States. This result is consistent with recent independent studies suggesting a systematic underestimation of CH4 emissions from North American fossil fuel sources in bottom-up inventories, likely related to natural gas production facilities. Furthermore, all four satellite inversions yield lower CH4 fluxes across the Congo basin compared to the NOAA-only scenario, but higher emissions across tropical East Africa. The GOSAT and SCIAMACHY inversions show similar performance when validated against independent shipboard and aircraft observations, and XCH4 retrievals available from the Total Carbon Column Observing Network (TCCON). ER - TY - JOUR T1 - Chlorine isotope composition in chlorofluorocarbons CFC-11, CFC-12 and CFC-113 in firn, stratospheric and tropospheric air A1 - Allin, S. J. A1 - Laube, J. C. A1 - Witrant, E. A1 - Kaiser, J. A1 - McKenna, E. A1 - Dennis, P. A1 - Mulvaney, R. A1 - Capron, E. A1 - Martinerie, P. A1 - Röckmann, T. A1 - Blunier, T. A1 - Schwander, J. A1 - Fraser, P. J. A1 - Langenfelds, R. L. A1 - Sturges, W. T. Y1 - 2015/06// JF - Atmospheric Chemistry and Physics VL - 15 IS - 12 SP - 6867 EP - 6877 DO - 10.5194/acp-15-6867-2015 UR - http://www.atmos-chem-phys.net/15/6867/2015/ N2 - The stratospheric degradation of chlorofluorocarbons (CFCs) releases chlorine, which is a major contributor to the destruction of stratospheric ozone (O3). A recent study reported strong chlorine isotope fractionation during the breakdown of the most abundant CFC (CFC-12, CCl2F2, Laube et al., 2010a), similar to effects seen in nitrous oxide (N2O). Using air archives to obtain a long-term record of chlorine isotope ratios in CFCs could help to identify and quantify their sources and sinks. We analyse the three most abundant CFCs and show that CFC-11 (CCl3F) and CFC-113 (CClF2CCl2F) exhibit significant stratospheric chlorine isotope fractionation, in common with CFC-12. The apparent isotope fractionation (ϵapp) for mid- and high-latitude stratospheric samples are respectively −2.4 (0.5) and −2.3 (0.4) ‰ for CFC-11, −12.2 (1.6) and −6.8 (0.8) ‰ for CFC-12 and −3.5 (1.5) and −3.3 (1.2) ‰ for CFC-113, where the number in parentheses is the numerical value of the standard uncertainty expressed in per mil. Assuming a constant isotope composition of emissions, we calculate the expected trends in the tropospheric isotope signature of these gases based on their stratospheric 37Cl enrichment and stratosphere–troposphere exchange. We compare these projections to the long-term δ (37Cl) trends of all three CFCs, measured on background tropospheric samples from the Cape Grim air archive (Tasmania, 1978–2010) and tropospheric firn air samples from Greenland (North Greenland Eemian Ice Drilling (NEEM) site) and Antarctica (Fletcher Promontory site). From 1970 to the present day, projected trends agree with tropospheric measurements, suggesting that within analytical uncertainties, a constant average emission isotope delta (δ) is a compatible scenario. The measurement uncertainty is too high to determine whether the average emission isotope δ has been affected by changes in CFC manufacturing processes or not. Our study increases the suite of trace gases amenable to direct isotope ratio measurements in small air volumes (approximately 200 mL), using a single-detector gas chromatography–mass spectrometry (GC–MS) system. ER - TY - JOUR T1 - A new method for continuous measurements of oceanic and atmospheric N2O, CO and CO2: performance of off-axis integrated cavity output spectroscopy (OA-ICOS) coupled to non-dispersive infrared detection (NDIR) A1 - Arévalo-Martínez, D. L. A1 - Beyer, M. A1 - Krumbholz, M. A1 - Piller, I. A1 - Kock, A. A1 - Steinhoff, T. A1 - Körtzinger, A. A1 - Bange, H. W. Y1 - 2013/12// JF - Ocean Science VL - 9 IS - 6 SP - 1071 EP - 1087 DO - 10.5194/os-9-1071-2013 UR - http://www.ocean-sci.net/9/1071/2013/ ER - TY - JOUR T1 - Massive nitrous oxide emissions from the tropical South Pacific Ocean A1 - Arévalo-Martínez, D. L. A1 - Kock, A. A1 - Löscher, C. R. A1 - Schmitz, R. A. A1 - Bange, H. W. Y1 - 2015/06// JF - Nature Geoscience VL - 8 IS - 7 SP - 530 EP - 533 DO - 10.1038/ngeo2469 UR - http://www.nature.com/doifinder/10.1038/ngeo2469 ER - TY - JOUR T1 - Influence of mesoscale eddies on the distribution of nitrous oxide in the eastern tropical South Pacific A1 - Arévalo-Martínez, D. L. A1 - Kock, A. A1 - Löscher, C. R. A1 - Schmitz, R. A. A1 - Stramma, L. A1 - Bange, H. W. Y1 - 2015/06// JF - Biogeosciences Discussions VL - 12 IS - 12 SP - 9243 EP - 9273 DO - 10.5194/bgd-12-9243-2015 UR - http://www.biogeosciences-discuss.net/12/9243/2015/ N2 - Recent observations in the eastern tropical South Pacific (ETSP) demonstrated the key role of meso- and submesoscale processes (e.g. eddies) in shaping its hydrographic and biogeochemical properties. Off Peru, elevated primary production from coastal upwelling in combination with sluggish ventilation of subsurface waters fuels a prominent oxygen minimum zone (OMZ). Given that nitrous oxide (N2O) production/consumption processes on the water column are sensitive to oxygen (O2) concentrations, the ETSP is a region of particular interest to investigate its source-sink dynamics. To date, no detailed surveys linking mesoscale processes and N2O distributions as well as their relevance to nitrogen (N) cycling are available. In this study, we present the first measurements of N2O across three mesoscale eddies (two mode water or anticyclonic and one cyclonic) which were identified, tracked and sampled during two surveys carried out in the ETSP in November-December 2012. A "two peak" structure was observed for N2O, wherein the two maxima coincide with the upper and lower boundaries of the OMZ, indicating active nitrification and partial denitrification. This was further supported by the abundances of the key gene for nitrification amoA and the gene marker for N2O production during denitrification, nirS. Conversely, we found strong N2O depletion in the core of the OMZ (O2 −1) to be consistent with nitrite (NO2−) accumulation and low levels of nitrate (NO3−), thus suggesting active denitrification. N2O depletion within the OMZ's core was substantially higher in the center of mode water eddies, supporting the view that eddy activity enhances N-loss processes off Peru, in particular near the shelf break where nutrient-rich, productive waters from upwelling are trapped before being transported offshore. Analysis of eddies during their propagation towards the open ocean showed that, in general, "aging" of mesoscale eddies tends to decrease N2O concentrations through the water column in response to reduced supply of material to fuel N-loss, although hydrographic variability might also significantly impact the pace of the production/consumption pathways for N2O. Our results demonstrate the relevance of mode water eddies for N2O distribution, thereby improving our understanding of the N-cycling processes, which are of crucial importance in times of climate change and ocean deoxygenation. ER - TY - JOUR T1 - Gas pooling: A sampling technique to overcome spatial heterogeneity of soil carbon dioxide and nitrous oxide fluxes A1 - Arias-Navarro, Cristina A1 - Díaz-Pinés, Eugenio A1 - Kiese, Ralf A1 - Rosenstock, Todd S. A1 - Rufino, Mariana C. A1 - Stern, David A1 - Neufeldt, Henry A1 - Verchot, Louis V. A1 - Butterbach-Bahl, Klaus Y1 - 2013/12// JF - Soil Biology and Biochemistry VL - 67 SP - 20 EP - 23 DO - 10.1016/j.soilbio.2013.08.011 UR - http://linkinghub.elsevier.com/retrieve/pii/S0038071713002769 ER - TY - JOUR T1 - HFC-43-10mee atmospheric abundances and global emission estimates A1 - Arnold, Tim A1 - Ivy, Diane J. A1 - Harth, Christina M. A1 - Vollmer, Martin K. A1 - Mühle, Jens A1 - Salameh, Peter K. A1 - Paul Steele, L. A1 - Krummel, Paul B. A1 - Wang, Ray H. J. A1 - Young, Dickon A1 - Lunder, Chris R. A1 - Hermansen, Ove A1 - Rhee, Tae Siek A1 - Kim, Jooil A1 - Reimann, Stefan A1 - O'Doherty, Simon A1 - Fraser, Paul J. A1 - Simmonds, Peter G. A1 - Prinn, Ronald G. A1 - Weiss, Ray F. Y1 - 2014/03// JF - Geophysical Research Letters VL - 41 IS - 6 SP - 2228 EP - 2235 DO - 10.1002/2013GL059143 UR - http://doi.wiley.com/10.1002/2013GL059143 ER - TY - JOUR T1 - Sampling frequency affects estimates of annual nitrous oxide fluxes A1 - Barton, L. A1 - Wolf, B. A1 - Rowlings, D. A1 - Scheer, C. A1 - Kiese, R. A1 - Grace, P. A1 - Stefanova, K. A1 - Butterbach-Bahl, K. Y1 - 2015/11// JF - Scientific Reports VL - 5 SP - 15912 EP - 15912 DO - 10.1038/srep15912 UR - http://www.nature.com/articles/srep15912 ER - TY - JOUR T1 - Towards better error statistics for atmospheric inversions of methane surface fluxes A1 - Berchet, A. A1 - Pison, I. A1 - Chevallier, F. A1 - Bousquet, P. A1 - Conil, S. A1 - Geever, M. A1 - Laurila, T. A1 - Lavrič, J. A1 - Lopez, M. A1 - Moncrieff, J. A1 - Necki, J. A1 - Ramonet, M. A1 - Schmidt, M. A1 - Steinbacher, M. A1 - Tarniewicz, J. Y1 - 2013/07// JF - Atmospheric Chemistry and Physics VL - 13 IS - 14 SP - 7115 EP - 7132 DO - 10.5194/acp-13-7115-2013 UR - http://www.atmos-chem-phys.net/13/7115/2013/ ER - TY - JOUR T1 - Top-down estimates of European CH4 and N2O emissions based on four different inverse models A1 - Bergamaschi, P. A1 - Corazza, M. A1 - Karstens, U. A1 - Athanassiadou, M. A1 - Thompson, R. L. A1 - Pison, I. A1 - Manning, A. J. A1 - Bousquet, P. A1 - Segers, A. A1 - Vermeulen, A. T. A1 - Janssens-Maenhout, G. A1 - Schmidt, M. A1 - Ramonet, M. A1 - Meinhardt, F. A1 - Aalto, T. A1 - Haszpra, L. A1 - Moncrieff, J. A1 - Popa, M. E. A1 - Lowry, D. A1 - Steinbacher, M. A1 - Jordan, A. A1 - O'Doherty, S. A1 - Piacentino, S. A1 - Dlugokencky, E. Y1 - 2015/01// JF - Atmospheric Chemistry and Physics VL - 15 IS - 2 SP - 715 EP - 736 DO - 10.5194/acp-15-715-2015 UR - http://www.atmos-chem-phys.net/15/715/2015/ N2 - European CH4 and N2O emissions are estimated for 2006 and 2007 using four inverse modelling systems, based on different global and regional Eulerian and Lagrangian transport models. This ensemble approach is designed to provide more realistic estimates of the overall uncertainties in the derived emissions, which is particularly important for verifying bottom-up emission inventories. We use continuous observations from 10 European stations (including 5 tall towers) for CH4 and 9 continuous stations for N2O, complemented by additional European and global discrete air sampling sites. The available observations mainly constrain CH4 and N2O emissions from north-western and eastern Europe. The inversions are strongly driven by the observations and the derived total emissions of larger countries show little dependence on the emission inventories used a priori. Three inverse models yield 26–56% higher total CH4 emissions from north-western and eastern Europe compared to bottom-up emissions reported to the UNFCCC, while one model is close to the UNFCCC values. In contrast, the inverse modelling estimates of European N2O emissions are in general close to the UNFCCC values, with the overall range from all models being much smaller than the UNFCCC uncertainty range for most countries. Our analysis suggests that the reported uncertainties for CH4 emissions might be underestimated, while those for N2O emissions are likely overestimated. ER - TY - JOUR T1 - HDO/H2O ratio retrievals from GOSAT A1 - Boesch, H. A1 - Deutscher, N. M. A1 - Warneke, T. A1 - Byckling, K. A1 - Cogan, A. J. A1 - Griffith, D. W. T. A1 - Notholt, J. A1 - Parker, R. J. A1 - Wang, Z. Y1 - 2013/03// JF - Atmospheric Measurement Techniques VL - 6 IS - 3 SP - 599 EP - 612 DO - 10.5194/amt-6-599-2013 UR - http://www.atmos-meas-tech.net/6/599/2013/ ER - TY - JOUR T1 - LIFE+IPNOA mobile prototype for the monitoring of soil N2O emissions from arable crops: first-year results on durum wheat A1 - Bosco, Simona A1 - Volpi, Iride A1 - Nassi o Di Nasso, Nicoletta A1 - Triana, Federico A1 - Roncucci, Neri A1 - Tozzini, Cristiano A1 - Villani, Ricardo A1 - Laville, Patricia A1 - Neri, Simone A1 - Mattei, Federica A1 - Virgili, Giorgio A1 - Nuvoli, Stefania A1 - Fabbrini, Luigi A1 - Bonari, Enrico Y1 - 2015/09// JF - Italian Journal of Agronomy VL - 10 IS - 3 SP - 124 EP - 124 DO - 10.4081/ija.2015.669 UR - http://www.agronomy.it/index.php/agro/article/view/669 N2 - Agricultural activities are co-responsible for the emission of the most important greenhouse gases: carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Development of methodologies to improve monitoring techniques for N2O are still needful. The LIFE+IPNOA project aims to improve the emissions monitoring of nitrous oxide from agricultural soils and to identify the agricultural practices that can limit N2O production. In order to achieve this objective, both a mobile and a stationary instrument were developed and validated. Several experimental field trials were set up in two different sites investigating the most representative crops of Tuscany (Central Italy), namely durum wheat, maize, sunflower, tomato and faba bean. The field trials were realized in order to test the effect on N2O emissions of key factors: tillage intensity, nitrogen fertiliser rate and irrigation. The field trial on durum wheat was set up in 2013 to test the effect of tillage intensity (minimum and conventional tillage) and nitrogen fertilisation rate (0, 110, 170 kg N ha-1) on soil N2O flux. Monitoring was carried out using the IPNOA mobile prototype. Preliminary results on N2O emissions for the durum wheat growing season showed that mean daily N2O fluxes ranged from –0.13 to 6.43 mg m-2 day-1 and cumulative N2O-N emissions over the period ranged from 827 to 2340 g N2O-N ha-1. Tillage did not affect N2O flux while increasing nitrogen fertilisation rate resulted to significantly increase N2O emissions. The IPNOA mobile prototype performed well during this first year of monitoring, allowing to catch both very low fluxes and peaks on N2O emissions after nitrogen supply, showing a good suitability to the field conditions. ER - TY - JOUR T1 - An extended Kalman-filter for regional scale inverse emission estimation A1 - Brunner, D. A1 - Henne, S. A1 - Keller, C. A. A1 - Reimann, S. A1 - Vollmer, M. K. A1 - O'Doherty, S. A1 - Maione, M. Y1 - 2012/04// JF - Atmospheric Chemistry and Physics VL - 12 IS - 7 SP - 3455 EP - 3478 DO - 10.5194/acp-12-3455-2012 UR - http://www.atmos-chem-phys.net/12/3455/2012/ ER - TY - JOUR T1 - Evaluation of a plot-scale methane emission model using eddy covariance observations and footprint modelling A1 - Budishchev, A. A1 - Mi, Y. A1 - van Huissteden, J. A1 - Belelli-Marchesini, L. A1 - Schaepman-Strub, G. A1 - Parmentier, F. J. W. A1 - Fratini, G. A1 - Gallagher, A. A1 - Maximov, T. C. A1 - Dolman, A. J. Y1 - 2014/09// JF - Biogeosciences VL - 11 IS - 17 SP - 4651 EP - 4664 DO - 10.5194/bg-11-4651-2014 UR - http://www.biogeosciences.net/11/4651/2014/ N2 - Most plot-scale methane emission models – of which many have been developed in the recent past – are validated using data collected with the closed-chamber technique. This method, however, suffers from a low spatial representativeness and a poor temporal resolution. Also, during a chamber-flux measurement the air within a chamber is separated from the ambient atmosphere, which negates the influence of wind on emissions. Additionally, some methane models are validated by upscaling fluxes based on the area-weighted averages of modelled fluxes, and by comparing those to the eddy covariance (EC) flux. This technique is rather inaccurate, as the area of upscaling might be different from the EC tower footprint, therefore introducing significant mismatch. In this study, we present an approach to validate plot-scale methane models with EC observations using the footprint-weighted average method. Our results show that the fluxes obtained by the footprint-weighted average method are of the same magnitude as the EC flux. More importantly, the temporal dynamics of the EC flux on a daily timescale are also captured (r2 = 0.7). In contrast, using the area-weighted average method yielded a low (r2 = 0.14) correlation with the EC measurements. This shows that the footprint-weighted average method is preferable when validating methane emission models with EC fluxes for areas with a heterogeneous and irregular vegetation pattern. ER - TY - JOUR T1 - Investigating uptake of N2O in agricultural soils using a high-precision dynamic chamber method A1 - Cowan, N. J. A1 - Famulari, D. A1 - Levy, P. E. A1 - Anderson, M. A1 - Reay, D. S. A1 - Skiba, U. M. Y1 - 2014/12// JF - Atmospheric Measurement Techniques VL - 7 IS - 12 SP - 4455 EP - 4462 DO - 10.5194/amt-7-4455-2014 UR - http://www.atmos-meas-tech.net/7/4455/2014/ N2 - Uptake (or negative flux) of nitrous oxide (N2O) in agricultural soils is a controversial issue which has proved difficult to investigate in the past due to constraints such as instrumental precision and methodological uncertainties. Using a recently developed high-precision quantum cascade laser gas analyser combined with a closed dynamic chamber, a well-defined detection limit of 4 μg N2O-N m−2 h−1 could be achieved for individual soil flux measurements. 1220 measurements of N2O flux were made from a variety of UK soils using this method, of which 115 indicated uptake by the soil (i.e. a negative flux in the micrometeorological sign convention). Only four of these apparently negative fluxes were greater than the detection limit of the method, which suggests that the vast majority of reported negative fluxes from such measurements are actually due to instrument noise. As such, we suggest that the bulk of negative N2O fluxes reported for agricultural fields are most likely due to limits in detection of a particular flux measurement methodology and not a result of microbiological activity consuming atmospheric N2O. ER - TY - JOUR T1 - The influence of tillage on N2O fluxes from an intensively managed grazed grassland in Scotland A1 - Cowan, N.J. A1 - Levy, P.E. A1 - Famulari, D. A1 - Anderson, M. A1 - Drewer, J. A1 - Carozzi, M. A1 - Reay, D.S. A1 - Skiba, U.M. Y1 - 2016/01// JF - Biogeosciences Discussions SP - 1 EP - 22 DO - 10.5194/bg-2015-643 UR - http://www.biogeosciences-discuss.net/bg-2015-643/ N2 - Intensively managed grass production in high rainfall temperate climate zones is a globally important source of N2O. Many of these grasslands are occasionally tilled and can lead to increased N2O emissions. This was investigated by comparing N2O fluxes from two adjacent intensively managed grazed grasslands in Scotland, one of which was tilled. A combination of eddy covariance, high resolution dynamic chamber and static chamber methods greatly improved the temporal and spatial coverage of N2O fluxes before and after the tillage event and is recommended to be followed in future studies. Total cumulative fluxes calculated for the tilled and un-tilled fields over the 175 day measurement period were 2.45 ± 0.27 and 2.08 ± 0.23 kg N2O-N ha−1, respectively. N2O emissions from the tilled field increased significantly for several days immediately after ploughing and remained elevated for approximately two months after the tillage event contributing to an estimated increase in N2O fluxes of 1.08 ± 0.14 kg N2O-N ha−1. Cumulative fluxes calculated over a 28 day period in August after the application of 70 kg-N ha−1 as ammonium nitrate to both fields were estimated at 0.42 ± 0.15 and 0.75 ± 0.14 kg N2O N ha−1 for the tilled and un-tilled fields, respectively. The tillage event appears to have substantially increased N2O fluxes from the tilled grassland field over a two month period; however, this increase may have been fractionally offset by a decrease in emissions after the August fertilisation event. ER - TY - JOUR T1 - Towards the integration of research and monitoring at forest ecosystems in Europe A1 - Danielewska, A. A1 - Paoletti, E. A1 - Clarke, N. A1 - Olejnik, J. A1 - Urbaniak, M. A1 - Baran, M. A1 - Siedlecki, P. A1 - Hansen, K. A1 - Lundin, L. A1 - De Vries, W. A1 - Nørgaard-Mikkelsen, T. A1 - Dillen, S. A1 - Fischer, R. Y1 - 2013/11// JF - Forest Systems VL - 22 IS - 3 SP - 535 EP - 535 DO - 10.5424/fs/2013223-03675 UR - http://revistas.inia.es/index.php/fs/article/view/3675 ER - TY - JOUR T1 - A meta-database comparison from various European Research and Monitoring Networks dedicated to forest sites A1 - Danielewska, A A1 - Clarke, N A1 - Olejnik, J A1 - Hansen, K A1 - Vries, W A1 - Lundin, L A1 - Tuovinen, J A1 - Fischer, R A1 - Urbaniak, M A1 - Paoletti, E Y1 - 2013/01// JF - iForest - Biogeosciences and Forestry VL - 6 IS - 1 SP - 1 EP - 9 DO - 10.3832/ifor0751-006 UR - http://www.sisef.it/iforest/?doi=10.3832/ifor0751-006 ER - TY - JOUR T1 - Nitrous oxide and methane in Atlantic and Mediterranean waters in the Strait of Gibraltar: Air-sea fluxes and inter-basin exchange A1 - de la Paz, M. A1 - Huertas, I.E. A1 - Flecha, S. A1 - Ríos, A.F. A1 - Pérez, F.F. Y1 - 2015/11// JF - Progress in Oceanography VL - 138 SP - 18 EP - 31 DO - 10.1016/j.pocean.2015.09.009 UR - http://linkinghub.elsevier.com/retrieve/pii/S0079661115001998 ER - TY - JOUR T1 - Inferring regional sources and sinks of atmospheric CO2 from GOSAT XCO2 data A1 - Deng, F. A1 - Jones, D. B. A. A1 - Henze, D. K. A1 - Bousserez, N. A1 - Bowman, K. W. A1 - Fisher, J. B. A1 - Nassar, R. A1 - O'Dell, C. A1 - Wunch, D. A1 - Wennberg, P. O. A1 - Kort, E. A. A1 - Wofsy, S. C. A1 - Blumenstock, T. A1 - Deutscher, N. M. A1 - Griffith, D. W. T. A1 - Hase, F. A1 - Heikkinen, P. A1 - Sherlock, V. A1 - Strong, K. A1 - Sussmann, R. A1 - Warneke, T. Y1 - 2014/04// JF - Atmospheric Chemistry and Physics VL - 14 IS - 7 SP - 3703 EP - 3727 DO - 10.5194/acp-14-3703-2014 UR - http://www.atmos-chem-phys.net/14/3703/2014/ N2 - We have examined the utility of retrieved column-averaged, dry-air mole fractions of CO2 (XCO2) from the Greenhouse Gases Observing Satellite (GOSAT) for quantifying monthly, regional flux estimates of CO2, using the GEOS-Chem four-dimensional variational (4D-Var) data assimilation system. We focused on assessing the potential impact of biases in the GOSAT CO2 data on the regional flux estimates. Using different screening and bias correction approaches, we selected three different subsets of the GOSAT XCO2 data for the 4D-Var inversion analyses, and found that the inferred global fluxes were consistent across the three XCO2 inversions. However, the GOSAT observational coverage was a challenge for the regional flux estimates. In the northern extratropics, the inversions were more sensitive to North American fluxes than to European and Asian fluxes due to the lack of observations over Eurasia in winter and over eastern and southern Asia in summer. The regional flux estimates were also sensitive to the treatment of the residual bias in the GOSAT XCO2 data. The largest differences obtained were for temperate North America and temperate South America, for which the largest spread between the inversions was 1.02 and 0.96 Pg C, respectively. In the case of temperate North America, one inversion suggested a strong source, whereas the second and third XCO2 inversions produced a weak and strong sink, respectively. Despite the discrepancies in the regional flux estimates between the three XCO2 inversions, the a posteriori CO2 distributions were in good agreement (with a mean difference between the three inversions of typically less than 0.5 ppm) with independent data from the Total Carbon Column Observing Network (TCCON), the surface flask network, and from the HIAPER Pole-to-Pole Observations (HIPPO) aircraft campaign. The discrepancy in the regional flux estimates from the different inversions, despite the agreement of the global flux estimates suggests the need for additional work to determine the minimum spatial scales at which we can reliably quantify the fluxes using GOSAT XCO2. The fact that the a posteriori CO2 from the different inversions were in good agreement with the independent data although the regional flux estimates differed significantly, suggests that innovative ways of exploiting existing data sets, and possibly additional observations, are needed to better evaluate the inferred regional flux estimates. ER - TY - JOUR T1 - Testing the applicability of neural networks as a gap-filling method using CH4 flux data from high latitude wetlands A1 - Dengel, S. A1 - Zona, D. A1 - Sachs, T. A1 - Aurela, M. A1 - Jammet, M. A1 - Parmentier, F. J. W. A1 - Oechel, W. A1 - Vesala, T. Y1 - 2013/12// JF - Biogeosciences VL - 10 IS - 12 SP - 8185 EP - 8200 DO - 10.5194/bg-10-8185-2013 UR - http://www.biogeosciences.net/10/8185/2013/ ER - TY - JOUR T1 - The Greenhouse Gas Climate Change Initiative (GHG-CCI): comparative validation of GHG-CCI SCIAMACHY/ENVISAT and TANSO-FTS/GOSAT CO2 and CH4 retrieval algorithm products with measurements from the TCCON A1 - Dils, B. A1 - Buchwitz, M. A1 - Reuter, M. A1 - Schneising, O. A1 - Boesch, H. A1 - Parker, R. A1 - Guerlet, S. A1 - Aben, I. A1 - Blumenstock, T. A1 - Burrows, J. P. A1 - Butz, A. A1 - Deutscher, N. M. A1 - Frankenberg, C. A1 - Hase, F. A1 - Hasekamp, O. P. A1 - Heymann, J. A1 - De Mazière, M. A1 - Notholt, J. A1 - Sussmann, R. A1 - Warneke, T. A1 - Griffith, D. A1 - Sherlock, V. A1 - Wunch, D. Y1 - 2014/06// JF - Atmospheric Measurement Techniques VL - 7 IS - 6 SP - 1723 EP - 1744 DO - 10.5194/amt-7-1723-2014 UR - http://www.atmos-meas-tech.net/7/1723/2014/ N2 - Column-averaged dry-air mole fractions of carbon dioxide and methane have been retrieved from spectra acquired by the TANSO-FTS (Thermal And Near-infrared Sensor for carbon Observations-Fourier Transform Spectrometer) and SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Cartography) instruments on board GOSAT (Greenhouse gases Observing SATellite) and ENVISAT (ENVIronmental SATellite), respectively, using a range of European retrieval algorithms. These retrievals have been compared with data from ground-based high-resolution Fourier transform spectrometers (FTSs) from the Total Carbon Column Observing Network (TCCON). The participating algorithms are the weighting function modified differential optical absorption spectroscopy (DOAS) algorithm (WFMD, University of Bremen), the Bremen optimal estimation DOAS algorithm (BESD, University of Bremen), the iterative maximum a posteriori DOAS (IMAP, Jet Propulsion Laboratory (JPL) and Netherlands Institute for Space Research algorithm (SRON)), the proxy and full-physics versions of SRON's RemoTeC algorithm (SRPR and SRFP, respectively) and the proxy and full-physics versions of the University of Leicester's adaptation of the OCO (Orbiting Carbon Observatory) algorithm (OCPR and OCFP, respectively). The goal of this algorithm inter-comparison was to identify strengths and weaknesses of the various so-called round- robin data sets generated with the various algorithms so as to determine which of the competing algorithms would proceed to the next round of the European Space Agency's (ESA) Greenhouse Gas Climate Change Initiative (GHG-CCI) project, which is the generation of the so-called Climate Research Data Package (CRDP), which is the first version of the Essential Climate Variable (ECV) "greenhouse gases" (GHGs). For XCO2, all algorithms reach the precision requirements for inverse modelling ( For XCH4, the precision for both SCIAMACHY products (50.2 ppb for IMAP and 76.4 ppb for WFMD) fails to meet the 4 precision ranges between 18.1 and 14.0 ppb. Looking at the SRA, all GOSAT algorithm products reach the ER - TY - JOUR T1 - Atmospheric station Křešín u Pacova, Czech Republic – a Central European research infrastructure for studying greenhouse gases, aerosols and air quality A1 - Dvorská, A. A1 - Sedlák, P. A1 - Schwarz, J. A1 - Fusek, M. A1 - Hanuš, V. A1 - Vodička, P. A1 - Trusina, J. Y1 - 2015/05// JF - Advances in Science and Research VL - 12 SP - 79 EP - 83 DO - 10.5194/asr-12-79-2015 UR - http://www.adv-sci-res.net/12/79/2015/ N2 - Long-lasting research infrastructures covering the research areas of atmospheric chemistry, meteorology and climatology are of highest importance. The Atmospheric Station (AS) Křešín u Pacova, central Czech Republic, is focused on monitoring of the occurence and long-range transport of greenhouse gases, atmospheric aerosols, selected gaseous atmospheric pollutants and basic meteorological characteristics. The AS and its 250 m tall tower was built according to the recommendations of the Integrated Carbon Observation System (ICOS) and cooperates with numerous national and international projects and monitoring programmes. First measurements conducted at ground started in 2012, vertical profile measurements were added in 2013. A seasonal variability with slightly higher autumn and winter concentrations of elemental and organic carbon was revealed. The suitability of the doubly left-censored Weibull distribution for modelling and interpretation of elemental carbon concentrations, which are often lower than instrumental quantification limits, was verified. Initial data analysis also suggests that in summer, the tower top at 250 m is frequently above the nocturnal surface inversions, thus being decoupled from local influences. ER - TY - JOUR T1 - Infrared Absorption Spectra, Radiative Efficiencies, and Global Warming Potentials of Newly-Detected Halogenated Compounds: CFC-113a, CFC-112 and HCFC-133a A1 - Etminan, Maryam A1 - Highwood, Eleanor A1 - Laube, Johannes A1 - McPheat, Robert A1 - Marston, George A1 - Shine, Keith A1 - Smith, Kevin Y1 - 2014/07// JF - Atmosphere VL - 5 IS - 3 SP - 473 EP - 483 DO - 10.3390/atmos5030473 UR - http://www.mdpi.com/2073-4433/5/3/473/ ER - TY - JOUR T1 - Real-time analysis of δ13C- and δD-CH4 in ambient air with laser spectroscopy: method development and first intercomparison results A1 - Eyer, S. A1 - Tuzson, B. A1 - Popa, M. E. A1 - van der Veen, C. A1 - Röckmann, T. A1 - Rothe, M. A1 - Brand, W. A. A1 - Fisher, R. A1 - Lowry, D. A1 - Nisbet, E. G. A1 - Brennwald, M. S. A1 - Harris, E. A1 - Zellweger, C. A1 - Emmenegger, L. A1 - Fischer, H. A1 - Mohn, J. Y1 - 2015/08// JF - Atmospheric Measurement Techniques Discussions VL - 8 IS - 8 SP - 8925 EP - 8970 DO - 10.5194/amtd-8-8925-2015 UR - http://www.atmos-meas-tech-discuss.net/8/8925/2015/ N2 - In situ and simultaneous measurement of the three most abundant isotopologues of methane using mid-infrared laser absorption spectroscopy is demonstrated. A field-deployable, autonomous platform is realized by coupling a compact quantum cascade laser absorption spectrometer (QCLAS) to a preconcentration unit, called TRace gas EXtractor (TREX). This unit enhances CH4 mole fractions by a factor of up to 500 above ambient levels and quantitatively separates interfering trace gases such as N2O and CO2. The analytical precision of the QCLAS isotope measurement on the preconcentrated (750 ppm, parts-per-million, μmole/mole) methane is 0.1 and 0.5 ‰ for δ13C- and δD-CH4 at 10 min averaging time. Based on replicate measurements of compressed air during a two-week intercomparison campaign, the repeatability of the TREX-QCLAS was determined to be 0.19 and 1.9 ‰ for δ13C and δD-CH4, respectively. In this intercomparison campaign the new in situ technique is compared to isotope-ratio mass-spectrometry (IRMS) based on glass flask and bag sampling and real time CH4 isotope analysis by two commercially available laser spectrometers. Both laser-based analyzers were limited to methane mole fraction and δ13C-CH4 analysis, and only one of them, a cavity ring down spectrometer, was capable to deliver meaningful data for the isotopic composition. After correcting for scale offsets, the average difference between TREX–QCLAS data and bag/flask sampling–IRMS values are within the extended WMO compatibility goals of 0.2 and 5 ‰ for δ13C- and δD-CH4, respectively. Thus, the intercomparison also reveals the need for reference air samples with accurately determined isotopic composition of CH4 to further improve the interlaboratory compatibility. ER - TY - JOUR T1 - Methane preconcentration by adsorption: a methodology for materials and conditions selection A1 - Eyer, Simon A1 - Stadie, Nicholas P. A1 - Borgschulte, Andreas A1 - Emmenegger, Lukas A1 - Mohn, Joachim Y1 - 2014/08// JF - Adsorption VL - 20 IS - 5-6 SP - 657 EP - 666 DO - 10.1007/s10450-014-9609-9 UR - http://link.springer.com/10.1007/s10450-014-9609-9 ER - TY - JOUR T1 - The open data debate: a need for accessible and shared data in forest science A1 - Fady, Bruno A1 - Benard, Alain A1 - Pichot, Christian A1 - Peiffer, Marianne A1 - Leban, Jean Michel A1 - Dreyer, Erwin Y1 - 2014/07// JF - Annals of Forest Science VL - 71 IS - 5 SP - 523 EP - 525 DO - 10.1007/s13595-014-0375-3 UR - http://link.springer.com/10.1007/s13595-014-0375-3 ER - TY - JOUR T1 - Elevated uptake of CO2 over Europe inferred from GOSAT XCO2 retrievals: a real phenomenon or an artefact of the analysis? A1 - Feng, L. A1 - Palmer, P. I. A1 - Parker, R. J. A1 - Deutscher, N. M. A1 - Feist, D. G. A1 - Kivi, R. A1 - Morino, I. A1 - Sussmann, R. Y1 - 2015/01// JF - Atmospheric Chemistry and Physics Discussions VL - 15 IS - 2 SP - 1989 EP - 2011 DO - 10.5194/acpd-15-1989-2015 UR - http://www.atmos-chem-phys-discuss.net/15/1989/2015/ N2 - Estimates of the natural CO2 flux over Europe inferred from in situ measurements of atmospheric CO2 mole fraction have been used previously to check top-down flux estimates inferred from space-borne dry-air CO2 column (XCO2) retrievals. Recent work has shown that CO2 fluxes inferred from XCO2 data from the Japanese Greenhouse gases Observing SATellite (GOSAT) have a larger seasonal amplitude and a more negative annual net CO2 balance than those inferred from the in situ data. The causes of this enhanced European CO2 uptake have since become the focus of recent studies. We show this elevated uptake over Europe could largely be explained by mis-fitting data due to regional biases. We establish a reference in situ inversion that uses an Ensemble Kalman Filter (EnKF) to assimilate surface flask data and the XCO2 data from the surface-based Total Carbon Column Observing Network (TCCON). The same EnKF system is also used to assimilate two, independent versions of GOSAT XCO2 data. We find that the GOSAT-inferred European terrestrial biosphere uptake peaks during the summer, similar to the reference inversion, but the net annual flux is 1.18 ± 0.1 GtC a−1 compared to a value of 0.56 ± 0.1 GtC a−1 for our control inversion that uses only in situ data. To reconcile these two estimates, we have performed a series of numerical experiments that assimilate observations with biases or assimilate synthetic observations for which part or all of the GOSAT XCO2 data are replaced with model data. We find that 50–80% of the elevated European uptake in 2010 inferred from GOSAT data is due to retrievals outside the immediate European region, while most of the remainder can be explained by a sub-ppm retrieval bias over Europe. We have used data assimilation techniques to estimate monthly GOSAT XCO2 biases from the joint assimilation of in situ observations and GOSAT XCO2 retrievals. We find a monthly varying bias of up to 0.5 ppm can explain an overestimate of the annual sink of up to 0.18 GtC a−1. ER - TY - JOUR T1 - Arctic methane sources: Isotopic evidence for atmospheric inputs A1 - Fisher, R. E. A1 - Sriskantharajah, S. A1 - Lowry, D. A1 - Lanoisellé, M. A1 - Fowler, C. M. R. A1 - James, R. H. A1 - Hermansen, O. A1 - Lund Myhre, C. A1 - Stohl, A. A1 - Greinert, J. A1 - Nisbet-Jones, P. B. R. A1 - Mienert, J. A1 - Nisbet, E. G. Y1 - 2011/11// JF - Geophysical Research Letters VL - 38 IS - 21 SP - n/a EP - n/a DO - 10.1029/2011GL049319 UR - http://doi.wiley.com/10.1029/2011GL049319 ER - TY - JOUR T1 - Estimating regional methane surface fluxes: the relative importance of surface and GOSAT mole fraction measurements A1 - Fraser, A. A1 - Palmer, P. I. A1 - Feng, L. A1 - Boesch, H. A1 - Cogan, A. A1 - Parker, R. A1 - Dlugokencky, E. J. A1 - Fraser, P. J. A1 - Krummel, P. B. A1 - Langenfelds, R. L. A1 - O'Doherty, S. A1 - Prinn, R. G. A1 - Steele, L. P. A1 - van der Schoot, M. A1 - Weiss, R. F. Y1 - 2013/06// JF - Atmospheric Chemistry and Physics VL - 13 IS - 11 SP - 5697 EP - 5713 DO - 10.5194/acp-13-5697-2013 UR - http://www.atmos-chem-phys.net/13/5697/2013/ ER - TY - JOUR T1 - Estimating regional fluxes of CO2 and CH4 using space-borne observations of XCH4 : XCO2 A1 - Fraser, A. A1 - Palmer, P. I. A1 - Feng, L. A1 - Bösch, H. A1 - Parker, R. A1 - Dlugokencky, E. J. A1 - Krummel, P. B. A1 - Langenfelds, R. L. Y1 - 2014/06// JF - Atmospheric Chemistry and Physics Discussions VL - 14 IS - 11 SP - 15867 EP - 15894 DO - 10.5194/acpd-14-15867-2014 UR - http://www.atmos-chem-phys-discuss.net/14/15867/2014/ N2 - We use the GEOS-Chem global 3-D atmospheric chemistry transport model to interpret XCH4:XCO2 column ratios retrieved using a proxy method from the Japanese Greenhouse gases Observing SATellite (GOSAT). The advantage of these data over CO2 and CH4 columns retrieved independently using a full physics optimal estimation algorithm is that they suffer less from scattering-related regional bias. We show the model is able to reproduce observed global and regional spatial (mean bias =0.7%) and temporal variations (global r2=0.92) of this ratio with model bias 2 and CH4 that are typically six months out of phase which may reduce the sensitivity of the ratio to changes in either gas. To simultaneously estimate fluxes of CO2 and CH4 we use a formal Bayesian inverse model infrastructure. We use two approaches to independently resolve flux estimates of these two gases using GOSAT observations of XCH4:XCO2: (1) the a priori error covariance between CO2 and CH4 describing common source from biomass burning; and (2) also fitting independent surface atmospheric measurements of CH4 and CO2 mole fraction that provide additional constraints, improving the effectiveness of the observed GOSAT ratio to constrain fluxes. We demonstrate the impact of these two approaches using Observing System Simulation Experiments. A posteriori flux estimates inferred using only the GOSAT ratios and taking advantage of the error covariance due to biomass burning are not consistent with the true fluxes in our experiments, as the inversion system cannot judge which species' fluxes to adjust. This can result in a posteriori fluxes that are further from the truth than the a priori fluxes. We find that adding the surface data to the inversion dramatically improves the ability of the GOSAT ratios to infer both CH4 and CO2 fluxes. We show that using real GOSAT XCH4:XCO2 ratios together with the surface data during 2010 outcompetes inversions using the individual XCH4 or the full-physics XCO2 data products. Regional fluxes that show the greatest improvements have model minus observation differences with a large seasonal cycle such as Tropical South America for which we report a small but significant annual source of CO2 compared to a small annual sink inferred from the XCO2 data. Based on our analysis we argue that using the ratios we may be reaching the limitations on the precision of these data. ER - TY - JOUR T1 - Australian carbon tetrachloride emissions in a global context A1 - Fraser, Paul J. A1 - Dunse, Bronwyn L. A1 - Manning, Alistair J. A1 - Walsh, Sean A1 - Wang, R. Hsiang J. A1 - Krummel, Paul B. A1 - Steele, L. Paul A1 - Porter, Laurie W. A1 - Allison, Colin A1 - O'Doherty, Simon A1 - Simmonds, Peter G. A1 - Mühle, Jens A1 - Weiss, Ray F. A1 - Prinn, Ronald G. Y1 - 2014/// JF - Environmental Chemistry VL - 11 IS - 1 SP - 77 EP - 77 DO - 10.1071/EN13171 UR - http://www.publish.csiro.au/?paper=EN13171 ER - TY - JOUR T1 - The impact of spectral resolution on satellite retrieval accuracy of CO2 and CH4 A1 - Galli, A. A1 - Guerlet, S. A1 - Butz, A. A1 - Aben, I. A1 - Suto, H. A1 - Kuze, A. A1 - Deutscher, N. M. A1 - Notholt, J. A1 - Wunch, D. A1 - Wennberg, P. O. A1 - Griffith, D. W. T. A1 - Hasekamp, O. A1 - Landgraf, J. Y1 - 2014/04// JF - Atmospheric Measurement Techniques VL - 7 IS - 4 SP - 1105 EP - 1119 DO - 10.5194/amt-7-1105-2014 UR - http://www.atmos-meas-tech.net/7/1105/2014/ N2 - The Fourier-transform spectrometer on board the Japanese GOSAT (Greenhouse gases Observing SATellite) satellite offers an excellent opportunity to study the impact of instrument resolution on retrieval accuracy of CO2 and CH4. This is relevant to further improve retrieval accuracy and to optimize the cost–benefit ratio of future satellite missions for the remote sensing of greenhouse gases. To address this question, we degrade GOSAT measurements with a spectral resolution of ≈ 0.24 cm−1 step by step to a resolution of 1.5 cm−1. We examine the results by comparing relative differences at various resolutions, by referring the results to reference values from the Total Carbon Column Observing Network (TCCON), and by calculating and inverting synthetic spectra for which the true CO2 and CH4 columns are known. The main impacts of degrading the spectral resolution are reproduced for all approaches based on GOSAT measurements; pure forward model errors identified with simulated measurements are much smaller. For GOSAT spectra, the most notable effect on CO2 retrieval accuracy is the increase of the standard deviation of retrieval errors from 0.7 to 1.0% when the spectral resolution is reduced by a factor of six. The retrieval biases against atmospheric water abundance and air mass become stronger with decreasing resolution. The error scatter increase for CH4 columns is less pronounced. The selective degradation of single spectral windows demonstrates that the retrieval accuracy of CO2 and CH4 is dominated by the spectral range where the absorption lines of the target molecule are located. For both GOSAT and synthetic measurements, retrieval accuracy decreases with lower spectral resolution for a given signal-to-noise ratio, suggesting increasing interference errors. ER - TY - JOUR T1 - Quantifying methane and nitrous oxide emissions from the UK and Ireland using a national-scale monitoring network A1 - Ganesan, A. L. A1 - Manning, A. J. A1 - Grant, A. A1 - Young, D. A1 - Oram, D .E. A1 - Sturges, W. T. A1 - Moncrieff, J. B. A1 - O'Doherty, S. Y1 - 2015/06// JF - Atmospheric Chemistry and Physics VL - 15 IS - 11 SP - 6393 EP - 6406 DO - 10.5194/acp-15-6393-2015 UR - http://www.atmos-chem-phys.net/15/6393/2015/ N2 - The UK is one of several countries around the world that has enacted legislation to reduce its greenhouse gas emissions. In this study, we present top-down emissions of methane (CH4) and nitrous oxide (N2O) for the UK and Ireland over the period August~2012 to August~2014. These emissions were inferred using measurements from a network of four sites around the two countries. We used a hierarchical Bayesian inverse framework to infer fluxes as well as a set of covariance parameters that describe uncertainties in the system. We inferred average UK total emissions of 2.09 (1.65–2.67) Tg yr−1 CH4 and 0.101 (0.068–0.150) Tg yr−1 N2O and found our derived UK estimates to be generally lower than the a priori emissions, which consisted primarily of anthropogenic sources and with a smaller contribution from natural sources. We used sectoral distributions from the UK National Atmospheric Emissions Inventory (NAEI) to determine whether these discrepancies can be attributed to specific source sectors. Because of the distinct distributions of the two dominant CH4 emissions sectors in the UK, agriculture and waste, we found that the inventory may be overestimated in agricultural CH4 emissions. We found that annual mean N2O emissions were consistent with both the prior and the anthropogenic inventory but we derived a significant seasonal cycle in emissions. This seasonality is likely due to seasonality in fertilizer application and in environmental drivers such as temperature and rainfall, which are not reflected in the annual resolution inventory. Through the hierarchical Bayesian inverse framework, we quantified uncertainty covariance parameters and emphasized their importance for high-resolution emissions estimation. We inferred average model errors of approximately 20 and 0.4 ppb and correlation timescales of 1.0 (0.72–1.43) and 2.6 (1.9–3.9) days for CH4 and N2O, respectively. These errors are a combination of transport model errors as well as errors due to unresolved emissions processes in the inventory. We found the largest CH4 errors at the Tacolneston station in eastern England, which may be due to sporadic emissions from landfills and offshore gas in the North Sea. ER - TY - JOUR T1 - European emissions of HCFC-22 based on eleven years of high frequency atmospheric measurements and a Bayesian inversion method A1 - Graziosi, F. A1 - Arduini, J. A1 - Furlani, F. A1 - Giostra, U. A1 - Kuijpers, L.J.M. A1 - Montzka, S.A. A1 - Miller, B.R. A1 - O'Doherty, S.J. A1 - Stohl, A. A1 - Bonasoni, P. A1 - Maione, M. Y1 - 2015/07// JF - Atmospheric Environment VL - 112 SP - 196 EP - 207 DO - 10.1016/j.atmosenv.2015.04.042 UR - http://linkinghub.elsevier.com/retrieve/pii/S1352231015300431 ER - TY - JOUR T1 - Impact of aerosol and thin cirrus on retrieving and validating XCO 2 from GOSAT shortwave infrared measurements A1 - Guerlet, S. A1 - Butz, A. A1 - Schepers, D. A1 - Basu, S. A1 - Hasekamp, O. P. A1 - Kuze, A. A1 - Yokota, T. A1 - Blavier, J.-F. A1 - Deutscher, N. M. A1 - Griffith, D. W. T. A1 - Hase, F. A1 - Kyro, E. A1 - Morino, I. A1 - Sherlock, V. A1 - Sussmann, R. A1 - Galli, A. A1 - Aben, I. Y1 - 2013/05// JF - Journal of Geophysical Research: Atmospheres VL - 118 IS - 10 SP - 4887 EP - 4905 DO - 10.1002/jgrd.50332 UR - http://doi.wiley.com/10.1002/jgrd.50332 ER - TY - JOUR T1 - Results from the International Halocarbons in Air Comparison Experiment (IHALACE) A1 - Hall, B. D. A1 - Engel, A. A1 - Mühle, J. A1 - Elkins, J. W. A1 - Artuso, F. A1 - Atlas, E. A1 - Aydin, M. A1 - Blake, D. A1 - Brunke, E.-G. A1 - Chiavarini, S. A1 - Fraser, P. J. A1 - Happell, J. A1 - Krummel, P. B. A1 - Levin, I. A1 - Loewenstein, M. A1 - Maione, M. A1 - Montzka, S. A. A1 - O'Doherty, S. A1 - Reimann, S. A1 - Rhoderick, G. A1 - Saltzman, E. S. A1 - Scheel, H. E. A1 - Steele, L. P. A1 - Vollmer, M. K. A1 - Weiss, R. F. A1 - Worthy, D. A1 - Yokouchi, Y. Y1 - 2014/02// JF - Atmospheric Measurement Techniques VL - 7 IS - 2 SP - 469 EP - 490 DO - 10.5194/amt-7-469-2014 UR - http://www.atmos-meas-tech.net/7/469/2014/ ER - TY - JOUR T1 - Assessment of a multi-species in situ FTIR for precise atmospheric greenhouse gas observations A1 - Hammer, S. A1 - Griffith, D. W. T. A1 - Konrad, G. A1 - Vardag, S. A1 - Caldow, C. A1 - Levin, I. Y1 - 2013/05// JF - Atmospheric Measurement Techniques VL - 6 IS - 5 SP - 1153 EP - 1170 DO - 10.5194/amt-6-1153-2013 UR - http://www.atmos-meas-tech.net/6/1153/2013/ ER - TY - JOUR T1 - Conceptual design of a measurement network of the global change A1 - Hari, P. A1 - Petäjä, T. A1 - Bäck, J. A1 - Kerminen, V.-M. A1 - Lappalainen, H. K. A1 - Vihma, T. A1 - Laurila, T. A1 - Viisanen, Y. A1 - Vesala, T. A1 - Kulmala, M. Y1 - 2015/08// JF - Atmospheric Chemistry and Physics Discussions VL - 15 IS - 15 SP - 21063 EP - 21093 DO - 10.5194/acpd-15-21063-2015 UR - http://www.atmos-chem-phys-discuss.net/15/21063/2015/ N2 - The global environment is changing rapidly due to anthropogenic emissions and actions. Such activities modify aerosol and greenhouse gas concentrations in the atmosphere, leading to regional and global climate change and affecting e.g. food and fresh-water security, sustainable use of natural resources and even demography. Here we present a conceptual design of a global, hierarchical observation network that can provide tools and increased understanding to tackle the inter-connected environmental and societal challenges that we will face in the coming decades. The philosophy behind the conceptual design relies on physical conservation laws of mass, energy and momentum, as well as on concentration gradients that act as driving forces for the atmosphere-biosphere exchange. The network is composed of standard, flux/advanced and flagship stations, each of which having specific and identified tasks. Each ecosystem type on the globe has its own characteristic features that have to be taken into consideration. The hierarchical network as a whole is able to tackle problems related to large spatial scales, heterogeneity of ecosystems and their complexity. The most comprehensive observations are envisioned to occur in flag ship stations, with which the process-level understanding can be expanded to continental and global scales together with advanced data analysis, earth system modelling and satellite remote sensing. The denser network of the flux and standard stations allow application and up-scaling of the results obtained from flag ship stations to the global level. ER - TY - JOUR T1 - Calibration of sealed HCl cells used for TCCON instrumental line shape monitoring A1 - Hase, F. A1 - Drouin, B. J. A1 - Roehl, C. M. A1 - Toon, G. C. A1 - Wennberg, P. O. A1 - Wunch, D. A1 - Blumenstock, T. A1 - Desmet, F. A1 - Feist, D. G. A1 - Heikkinen, P. A1 - De Mazière, M. A1 - Rettinger, M. A1 - Robinson, J. A1 - Schneider, M. A1 - Sherlock, V. A1 - Sussmann, R. A1 - Té, Y. A1 - Warneke, T. A1 - Weinzierl, C. Y1 - 2013/12// JF - Atmospheric Measurement Techniques VL - 6 IS - 12 SP - 3527 EP - 3537 DO - 10.5194/amt-6-3527-2013 UR - http://www.atmos-meas-tech.net/6/3527/2013/ ER - TY - JOUR T1 - How well do tall-tower measurements characterize the CO2 mole fraction distribution in the planetary boundary layer? A1 - Haszpra, L. A1 - Barcza, Z. A1 - Haszpra, T. A1 - Pátkai, Zs. A1 - Davis, K. J. Y1 - 2015/04// JF - Atmospheric Measurement Techniques VL - 8 IS - 4 SP - 1657 EP - 1671 DO - 10.5194/amt-8-1657-2015 UR - http://www.atmos-meas-tech.net/8/1657/2015/ N2 - Planetary boundary layer (PBL) CO2 mole fraction data are needed by transport models and carbon budget models as both input and reference for validation. The height of in situ CO2 mole fraction measurements is usually different from that of the model levels where the data are needed; data from short towers, in particular, are difficult to utilize in atmospheric models that do not simulate the surface layer well. Tall-tower CO2 mole fraction measurements observed at heights ranging from 10 to 115 m above ground level at a rural site in Hungary and regular airborne vertical mole fraction profile measurements (136 vertical profiles) above the tower allowed us to estimate how well a tower of a given height could estimate the CO2 mole fraction above the tower in the PBL. The statistical evaluation of the height-dependent bias between the real PBL CO2 mole fraction profile (measured by the aircraft) and the measurement at a given elevation above the ground was performed separately for the summer and winter half years to take into account the different dynamics of the lower troposphere and the different surface CO2 flux in the different seasons. The paper presents (1) how accurately the vertical distribution of CO2 in the PBL can be estimated from the measurements on the top of a tower of height H; (2) how tall of a tower would be needed for the satisfaction of different requirements on the accuracy of the estimation of the CO2 vertical distribution; (3) how accurate of a CO2 vertical distribution estimation can be expected from the existing towers; and (4) how much improvement can be achieved in the accuracy of the estimation of CO2 vertical distribution by applying the virtual tall-tower concept. ER - TY - JOUR T1 - Contribution of oil and natural gas production to renewed increase of atmospheric methane (2007&ndash;2014): top-down estimate from ethane and methane column observations A1 - Hausmann, P. A1 - Sussmann, R. A1 - Smale, D. Y1 - 2015/12// JF - Atmospheric Chemistry and Physics Discussions VL - 15 IS - 24 SP - 35991 EP - 36028 DO - 10.5194/acpd-15-35991-2015 UR - http://www.atmos-chem-phys-discuss.net/15/35991/2015/ N2 - Harmonized time series of column-averaged mole fractions of atmospheric methane and ethane over the period 1999–2014 are derived from solar Fourier transform infrared (FTIR) measurements at the Zugspitze summit (47° N, 2964 m a.s.l.) and at Lauder (45° S, 370 m a.s.l.). Long-term trend analysis reveals a consistent renewed methane increase since 2007 of 6.2 [5.6, 6.9] ppb yr−1 at the Zugspitze and 6.0 [5.3, 6.7] ppb yr−1 at Lauder (95 % confidence intervals). Several recent studies provide pieces of evidence that the renewed methane increase is most likely driven by two main factors: (i) increased methane emissions from tropical wetlands, followed by (ii) increased thermogenic methane emissions due to growing oil and natural gas production. Here, we quantify the magnitude of the second class of sources, using long-term measurements of atmospheric ethane as tracer for thermogenic methane emissions. In 2007, after years of weak decline, the Zugspitze ethane time series shows the sudden onset of a significant positive trend (2.3 [1.8, 2.8] × 10-2 ppb yr−1 for 2007–2014), while a negative trend persists at Lauder after 2007 (−0.4 [−0.6, −0.1] × 10-2 ppb yr−1). Zugspitze methane and ethane time series are significantly correlated for the period 2007–2014 and can be assigned to thermogenic methane emissions with an ethane-to-methane ratio of 10–21 %. We present optimized emission scenarios for 2007–2014 derived from an atmospheric two-box model. From our trend observations we infer a total ethane emission increase over the period 2007–2014 from oil and natural gas sources of 1–11 Tg yr−1 along with an overall methane emission increase of 24–45 Tg yr−1. Based on these results, the oil and natural gas emission contribution C to the renewed methane increase is deduced using three different emission scenarios with dedicated ranges of methane-to-ethane ratios (MER). Reference scenario 1 assumes an oil and gas emission combination with MER = 3.3–7.6, which results in a minimum contribution C > 28 % (given as lower bound of 99 % confidence interval). For the limiting cases of pure oil-related emissions with MER = 1.7–3.3 (scenario 2) and pure natural gas sources with MER = 7.6–12.1 (scenario 3) the results are C > 13 % and C > 53 %, respectively. Our results suggest that long-term observations of column-averaged ethane provide a valuable constraint on the source attribution of methane emission changes and provide basic knowledge for developing effective climate change mitigation strategies. ER - TY - JOUR T1 - Effects of cooling and internal wave motions on gas transfer coefficients in a boreal lake A1 - Heiskanen, JOUNI J. A1 - Mammarella, IVAN A1 - Haapanala, SAMI A1 - Pumpanen, JUKKA A1 - Vesala, TIMO A1 - MacIntyre, SALLY A1 - Ojala, ANNE Y1 - 2014/05// JF - Tellus B VL - 66 IS - 0 DO - 10.3402/tellusb.v66.22827 UR - http://www.tellusb.net/index.php/tellusb/article/view/22827 ER - TY - JOUR T1 - Effects of water clarity on lake stratification and lake-atmosphere heat exchange A1 - Heiskanen, Jouni J. A1 - Mammarella, Ivan A1 - Ojala, Anne A1 - Stepanenko, Victor A1 - Erkkilä, Kukka-Maaria A1 - Miettinen, Heli A1 - Sandström, Heidi A1 - Eugster, Werner A1 - Leppäranta, Matti A1 - Järvinen, Heikki A1 - Vesala, Timo A1 - Nordbo, Annika Y1 - 2015/08// JF - Journal of Geophysical Research: Atmospheres VL - 120 IS - 15 SP - 7412 EP - 7428 DO - 10.1002/2014JD022938 UR - http://doi.wiley.com/10.1002/2014JD022938 ER - TY - JOUR T1 - Footprint Evaluation for Flux and Concentration Measurements for an Urban-Like Canopy with Coupled Lagrangian Stochastic and Large-Eddy Simulation Models A1 - Hellsten, Antti A1 - Luukkonen, Sofia-M. A1 - Steinfeld, Gerald A1 - Kanani-Sühring, Farah A1 - Markkanen, Tiina A1 - Järvi, Leena A1 - Lento, Juha A1 - Vesala, Timo A1 - Raasch, Siegfried Y1 - 2015/11// JF - Boundary-Layer Meteorology VL - 157 IS - 2 SP - 191 EP - 217 DO - 10.1007/s10546-015-0062-4 UR - http://link.springer.com/10.1007/s10546-015-0062-4 ER - TY - JOUR T1 - Low cost and state of the art methods to measure nitrous oxide emissions A1 - Hensen, Arjan A1 - Skiba, Ute A1 - Famulari, Daniela Y1 - 2013/06// JF - Environmental Research Letters VL - 8 IS - 2 SP - 025022 EP - 025022 DO - 10.1088/1748-9326/8/2/025022 UR - http://stacks.iop.org/1748-9326/8/i=2/a=025022?key=crossref.06fe71ce5ce997875305d33a5e049fcd ER - TY - JOUR T1 - SCIAMACHY WFM-DOAS XCO2: reduction of scattering related errors A1 - Heymann, J. A1 - Bovensmann, H. A1 - Buchwitz, M. A1 - Burrows, J. P. A1 - Deutscher, N. M. A1 - Notholt, J. A1 - Rettinger, M. A1 - Reuter, M. A1 - Schneising, O. A1 - Sussmann, R. A1 - Warneke, T. Y1 - 2012/10// JF - Atmospheric Measurement Techniques VL - 5 IS - 10 SP - 2375 EP - 2390 DO - 10.5194/amt-5-2375-2012 UR - http://www.atmos-meas-tech.net/5/2375/2012/ ER - TY - JOUR T1 - Observing wind, aerosol particles, cloud and precipitation: Finland's new ground-based remote-sensing network A1 - Hirsikko, A. A1 - O'Connor, E. J. A1 - Komppula, M. A1 - Korhonen, K. A1 - Pfüller, A. A1 - Giannakaki, E. A1 - Wood, C. R. A1 - Bauer-Pfundstein, M. A1 - Poikonen, A. A1 - Karppinen, T. A1 - Lonka, H. A1 - Kurri, M. A1 - Heinonen, J. A1 - Moisseev, D. A1 - Asmi, E. A1 - Aaltonen, V. A1 - Nordbo, A. A1 - Rodriguez, E. A1 - Lihavainen, H. A1 - Laaksonen, A. A1 - Lehtinen, K. E. J. A1 - Laurila, T. A1 - Petäjä, T. A1 - Kulmala, M. A1 - Viisanen, Y. Y1 - 2014/05// JF - Atmospheric Measurement Techniques VL - 7 IS - 5 SP - 1351 EP - 1375 DO - 10.5194/amt-7-1351-2014 UR - http://www.atmos-meas-tech.net/7/1351/2014/ N2 - The Finnish Meteorological Institute, in collaboration with the University of Helsinki, has established a new ground-based remote-sensing network in Finland. The network consists of five topographically, ecologically and climatically different sites distributed from southern to northern Finland. The main goal of the network is to monitor air pollution and boundary layer properties in near real time, with a Doppler lidar and ceilometer at each site. In addition to these operational tasks, two sites are members of the Aerosols, Clouds and Trace gases Research InfraStructure Network (ACTRIS); a Ka band cloud radar at Sodankylä will provide cloud retrievals within CloudNet, and a multi-wavelength Raman lidar, PollyXT (POrtabLe Lidar sYstem eXTended), in Kuopio provides optical and microphysical aerosol properties through EARLINET (the European Aerosol Research Lidar Network). Three C-band weather radars are located in the Helsinki metropolitan area and are deployed for operational and research applications. We performed two inter-comparison campaigns to investigate the Doppler lidar performance, compare the backscatter signal and wind profiles, and to optimize the lidar sensitivity through adjusting the telescope focus length and data-integration time to ensure sufficient signal-to-noise ratio (SNR) in low-aerosol-content environments. In terms of statistical characterization, the wind-profile comparison showed good agreement between different lidars. Initially, there was a discrepancy in the SNR and attenuated backscatter coefficient profiles which arose from an incorrectly reported telescope focus setting from one instrument, together with the need to calibrate. After diagnosing the true telescope focus length, calculating a new attenuated backscatter coefficient profile with the new telescope function and taking into account calibration, the resulting attenuated backscatter profiles all showed good agreement with each other. It was thought that harsh Finnish winters could pose problems, but, due to the built-in heating systems, low ambient temperatures had no, or only a minor, impact on the lidar operation – including scanning-head motion. However, accumulation of snow and ice on the lens has been observed, which can lead to the formation of a water/ice layer thus attenuating the signal inconsistently. Thus, care must be taken to ensure continuous snow removal. ER - TY - JOUR T1 - Comparison of GC/time-of-flight MS with GC/quadrupole MS for halocarbon trace gas analysis A1 - Hoker, J. A1 - Obersteiner, F. A1 - Bönisch, H. A1 - Engel, A. Y1 - 2015/05// JF - Atmospheric Measurement Techniques VL - 8 IS - 5 SP - 2195 EP - 2206 DO - 10.5194/amt-8-2195-2015 UR - http://www.atmos-meas-tech.net/8/2195/2015/ N2 - We present the application of time-of-flight mass spectrometry (TOF MS) for the analysis of halocarbons in the atmosphere after cryogenic sample preconcentration and gas chromatographic separation. For the described field of application, the quadrupole mass spectrometer (QP MS) is a state-of-the-art detector. This work aims at comparing two commercially available instruments, a QP MS and a TOF MS, with respect to mass resolution, mass accuracy, stability of the mass axis and instrument sensitivity, detector sensitivity, measurement precision and detector linearity. Both mass spectrometers are operated on the same gas chromatographic system by splitting the column effluent to both detectors. The QP MS had to be operated in optimised single ion monitoring (SIM) mode to achieve a sensitivity which could compete with the TOF MS. The TOF MS provided full mass range information in any acquired mass spectrum without losing sensitivity. Whilst the QP MS showed the performance already achieved in earlier tests, the sensitivity of the TOF MS was on average higher than that of the QP MS in the "operational" SIM mode by a factor of up to 3, reaching detection limits of less than 0.2 pg. Measurement precision determined for the whole analytical system was up to 0.2% depending on substance and sampled volume. The TOF MS instrument used for this study displayed significant non-linearities of up to 10% for two-thirds of all analysed substances. ER - TY - JOUR T1 - Comparison of MOD16 and LSA-SAF MSG evapotranspiration products over Europe for 2011 A1 - Hu, Guangcheng A1 - Jia, Li A1 - Menenti, Massimo Y1 - 2015/01// JF - Remote Sensing of Environment VL - 156 SP - 510 EP - 526 DO - 10.1016/j.rse.2014.10.017 UR - http://linkinghub.elsevier.com/retrieve/pii/S0034425714004271 ER - TY - JOUR T1 - Efficient gas exchange between a boreal river and the atmosphere A1 - Huotari, Jussi A1 - Haapanala, Sami A1 - Pumpanen, Jukka A1 - Vesala, Timo A1 - Ojala, Anne Y1 - 2013/11// JF - Geophysical Research Letters VL - 40 IS - 21 SP - 5683 EP - 5686 DO - 10.1002/2013GL057705 UR - http://doi.wiley.com/10.1002/2013GL057705 ER - TY - JOUR T1 - Bias corrections of GOSAT SWIR XCO2 and XCH4 with TCCON data and their evaluation using aircraft measurement data A1 - Inoue, M. A1 - Morino, I. A1 - Uchino, O. A1 - Nakatsuru, T. A1 - Yoshida, Y. A1 - Yokota, T. A1 - Wunch, D. A1 - Wennberg, P. O. A1 - Roehl, C. M. A1 - Griffith, D. W. T. A1 - Velazco, V. A. A1 - Deutscher, N. M. A1 - Warneke, T. A1 - Notholt, J. A1 - Robinson, J. A1 - Sherlock, V. A1 - Hase, F. A1 - Blumenstock, T. A1 - Rettinger, M. A1 - Sussmann, R. A1 - Kyrö, E. A1 - Kivi, R. A1 - Shiomi, K. A1 - Kawakami, S. A1 - De Mazière, M. A1 - Arnold, S. G. A1 - Feist, D. G. A1 - Barrow, E. A. A1 - Barney, J. A1 - Dubey, M. A1 - Schneider, M. A1 - Iraci, L. A1 - Podolske, J. R. A1 - Hillyard, P. A1 - Machida, T. A1 - Sawa, Y. A1 - Tsuboi, K. A1 - Matsueda, H. A1 - Sweeney, C. A1 - Tans, P. P. A1 - Andrews, A. E. A1 - Biraud, S. C. A1 - Fukuyama, Y. A1 - Pittman, J. V. A1 - Kort, E. A. A1 - Tanaka, T. Y1 - 2016/01// JF - Atmospheric Measurement Techniques Discussions SP - 1 EP - 49 DO - 10.5194/amt-2015-366 UR - http://www.atmos-meas-tech-discuss.net/amt-2015-366/ N2 - We describe a method for removing systematic biases of column-averaged dry air mole fractions of CO2 (XCO2) and CH4 (XCH4) derived from short-wavelength infrared (SWIR) spectra of the Greenhouse gases Observing SATellite (GOSAT). We conduct correlation analyses between the GOSAT biases and simultaneously-retrieved auxiliary parameters. We use these correlations to bias correct the GOSAT data, removing these spurious correlations. Data from Total Carbon Column Observing Network (TCCON) were used as reference values for this regression analysis. To evaluate the effectiveness of this correction method, the uncorrected/corrected GOSAT data were compared to independent XCO2 and XCH4 data derived from aircraft measurements taken for the Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL) project, the National Oceanic and Atmospheric Administration (NOAA), the U.S. Department of Energy (DOE), the National Institute for Environmental Studies (NIES), the Japan Meteorological Agency (JMA), the HIAPER Pole- to-Pole observations (HIPPO) program, and the GOSAT validation aircraft observation campaign over Japan. These comparisons demonstrate that the empirically-derived bias correction improves the agreement between GOSAT XCO2/XCH4 and the aircraft data. Finally, we present latitudinal distributions and temporal variations of the derived GOSAT biases. ER - TY - JOUR T1 - Biases in methane chamber measurements in peatlands A1 - Juszczak, R. Y1 - 2013/01// JF - International Agrophysics VL - 27 IS - 2 DO - 10.2478/v10247-012-0081-z UR - http://www.degruyter.com/view/j/intag.2013.27.issue-2/v10247-012-0081-z/v10247-012-0081-z.xml ER - TY - JOUR T1 - Exchange of the Greenhouse Gases Methane and Nitrous Oxide Between the Atmosphere and a Temperate Peatland in Central Europe A1 - Juszczak, Radosław A1 - Augustin, Jürgen Y1 - 2013/10// JF - Wetlands VL - 33 IS - 5 SP - 895 EP - 907 DO - 10.1007/s13157-013-0448-3 UR - http://link.springer.com/10.1007/s13157-013-0448-3 ER - TY - JOUR T1 - A process-based 222radon flux map for Europe and its comparison to long-term observations A1 - Karstens, U. A1 - Schwingshackl, C. A1 - Schmithüsen, D. A1 - Levin, I. Y1 - 2015/11// JF - Atmospheric Chemistry and Physics VL - 15 IS - 22 SP - 12845 EP - 12865 DO - 10.5194/acp-15-12845-2015 UR - http://www.atmos-chem-phys.net/15/12845/2015/ N2 - Detailed 222radon (222Rn) flux maps are an essential pre-requisite for the use of radon in atmospheric transport studies. Here we present a high-resolution 222Rn flux map for Europe, based on a parameterization of 222Rn production and transport in the soil. The 222Rn exhalation rate is parameterized based on soil properties, uranium content, and modelled soil moisture from two different land-surface reanalysis data sets. Spatial variations in exhalation rates are primarily determined by the uranium content of the soil, but also influenced by soil texture and local water-table depth. Temporal variations are related to soil moisture variations as the molecular diffusion in the unsaturated soil zone depends on available air-filled pore space. The implemented diffusion parameterization was tested against campaign-based 222Rn soil profile measurements. Monthly 222Rn exhalation rates from European soils were calculated with a nominal spatial resolution of 0.083° × 0.083° and compared to long-term direct measurements of 222Rn exhalation rates in different areas of Europe. The two realizations of the 222Rn flux map, based on the different soil moisture data sets, both realistically reproduce the observed seasonality in the fluxes but yield considerable differences for absolute flux values. The mean 222Rn flux from soils in Europe is estimated to be 10 mBq m−2 s−1 (ERA-Interim/Land soil moisture) or 15 mBq m−2 s−1 (GLDAS (Global Land Data Assimilation System) Noah soil moisture) for the period 2006–2010. The corresponding seasonal variations with low fluxes in winter and high fluxes in summer range in the two realizations from ca. 7 to ca. 14 mBq m−2 s−1 and from ca. 11 to ca. 20 mBq m−2 s−1, respectively. These systematic differences highlight the importance of realistic soil moisture data for a reliable estimation of 222Rn exhalation rates. Comparison with observations suggests that the flux estimates based on the GLDAS Noah soil moisture model on average better represent observed fluxes. ER - TY - JOUR T1 - Latent heat exchange in the boreal and arctic biomes A1 - Kasurinen, Ville A1 - Alfredsen, Knut A1 - Kolari, Pasi A1 - Mammarella, Ivan A1 - Alekseychik, Pavel A1 - Rinne, Janne A1 - Vesala, Timo A1 - Bernier, Pierre A1 - Boike, Julia A1 - Langer, Moritz A1 - Belelli Marchesini, Luca A1 - van Huissteden, Ko A1 - Dolman, Han A1 - Sachs, Torsten A1 - Ohta, Takeshi A1 - Varlagin, Andrej A1 - Rocha, Adrian A1 - Arain, Altaf A1 - Oechel, Walter A1 - Lund, Magnus A1 - Grelle, Achim A1 - Lindroth, Anders A1 - Black, Andy A1 - Aurela, Mika A1 - Laurila, Tuomas A1 - Lohila, Annalea A1 - Berninger, Frank Y1 - 2014/11// JF - Global Change Biology VL - 20 IS - 11 SP - 3439 EP - 3456 DO - 10.1111/gcb.12640 UR - http://doi.wiley.com/10.1111/gcb.12640 ER - TY - JOUR T1 - Ubiquity of organic nitrates from nighttime chemistry in the European submicron aerosol A1 - Kiendler-Scharr, A. A1 - Mensah, A. A. A1 - Friese, E. A1 - Topping, D. A1 - Nemitz, E. A1 - Prevot, A. S. H. A1 - Äijälä, M. A1 - Allan, J. A1 - Canonaco, F. A1 - Canagaratna, M. A1 - Carbone, S. A1 - Crippa, M. A1 - Dall Osto, M. A1 - Day, D. A. A1 - De Carlo, P. A1 - Di Marco, C. F. A1 - Elbern, H. A1 - Eriksson, A. A1 - Freney, E. A1 - Hao, L. A1 - Herrmann, H. A1 - Hildebrandt, L. A1 - Hillamo, R. A1 - Jimenez, J. L. A1 - Laaksonen, A. A1 - McFiggans, G. A1 - Mohr, C. A1 - O'Dowd, C. A1 - Otjes, R. A1 - Ovadnevaite, J. A1 - Pandis, S. N. A1 - Poulain, L. A1 - Schlag, P. A1 - Sellegri, K. A1 - Swietlicki, E. A1 - Tiitta, P. A1 - Vermeulen, A. A1 - Wahner, A. A1 - Worsnop, D. A1 - Wu, H.-C. Y1 - 2016/07// JF - Geophysical Research Letters VL - 43 IS - 14 SP - 7735 EP - 7744 DO - 10.1002/2016GL069239 UR - http://onlinelibrary.wiley.com/doi/10.1002/2016GL069239/abstract UR - http://doi.wiley.com/10.1002/2016GL069239 L1 - file:///C:/Users/alex.vermeulen/Documents/Kiendler-Scharr_et_al-2016-Geophysical_Research_Letters.pdf N2 - In the atmosphere nighttime removal of volatile organic compounds is initiated to a large extent by reaction with the nitrate radical (NO3) forming organic nitrates which partition between gas and particulate phase. Here we show based on particle phase measurements performed at a suburban site in the Netherlands that organic nitrates contribute substantially to particulate nitrate and organic mass. Comparisons with a chemistry transport model indicate that most of the measured particulate organic nitrates are formed by NO3 oxidation. Using aerosol composition data from three intensive observation periods at numerous measurement sites across Europe, we conclude that organic nitrates are a considerable fraction of fine particulate matter (PM1) at the continental scale. Organic nitrates represent 34% to 44% of measured submicron aerosol nitrate and are found at all urban and rural sites, implying a substantial potential of PM reduction by NOx emission control. ER - TY - JOUR T1 - Three decades of global methane sources and sinks A1 - Kirschke, Stefanie A1 - Bousquet, Philippe A1 - Ciais, Philippe A1 - Saunois, Marielle A1 - Canadell, Josep G. A1 - Dlugokencky, Edward J. A1 - Bergamaschi, Peter A1 - Bergmann, Daniel A1 - Blake, Donald R. A1 - Bruhwiler, Lori A1 - Cameron-Smith, Philip A1 - Castaldi, Simona A1 - Chevallier, Frédéric A1 - Feng, Liang A1 - Fraser, Annemarie A1 - Heimann, Martin A1 - Hodson, Elke L. A1 - Houweling, Sander A1 - Josse, Béatrice A1 - Fraser, Paul J. A1 - Krummel, Paul B. A1 - Lamarque, Jean-François A1 - Langenfelds, Ray L. A1 - Le Quéré, Corinne A1 - Naik, Vaishali A1 - O'Doherty, Simon A1 - Palmer, Paul I. A1 - Pison, Isabelle A1 - Plummer, David A1 - Poulter, Benjamin A1 - Prinn, Ronald G. A1 - Rigby, Matt A1 - Ringeval, Bruno A1 - Santini, Monia A1 - Schmidt, Martina A1 - Shindell, Drew T. A1 - Simpson, Isobel J. A1 - Spahni, Renato A1 - Steele, L. Paul A1 - Strode, Sarah A. A1 - Sudo, Kengo A1 - Szopa, Sophie A1 - van der Werf, Guido R. A1 - Voulgarakis, Apostolos A1 - van Weele, Michiel A1 - Weiss, Ray F. A1 - Williams, Jason E. A1 - Zeng, Guang Y1 - 2013/09// JF - Nature Geoscience VL - 6 IS - 10 SP - 813 EP - 823 DO - 10.1038/ngeo1955 UR - http://www.nature.com/doifinder/10.1038/ngeo1955 ER - TY - JOUR T1 - Evaluation of the boundary layer dynamics of the TM5 model A1 - Koffi, E N A1 - Bergamaschi, P A1 - Karstens, U A1 - Krol, M A1 - Segers, A A1 - Schmidt, M A1 - Levin, I A1 - Vermeulen, A T A1 - Fisher, R E A1 - Kazan, V A1 - Klein Baltink, H A1 - Lowry, D A1 - Manca, G A1 - Meijer, H A J A1 - Moncrieff, J A1 - Pal, S A1 - Ramonet, M A1 - Scheeren, H A Y1 - 2016/03// PB - Copernicus Publications JF - Geoscientific Model Development Discussions VL - 2016 SP - 1 EP - 37 DO - 10.5194/gmd-2016-48 UR - http://www.geosci-model-dev-discuss.net/gmd-2016-48/ UR - http://www.geosci-model-dev-discuss.net/gmd-2016-48/gmd-2016-48.pdf N2 - We evaluate the capability of the global atmospheric transport model TM5 to reproduce observations of the boundary layer dynamics and the associated variability of trace gases close to the surface, using radon (222Rn), which is an excellent tracer for vertical mixing owing to its short lifetime (half-life) of 3.82 days. Focusing on the European scale, we compare the boundary layer height (BLH) in the TM5 model with observations from the NOAA Integrated Global Radiosonde Archive (IGRA) and in addition with ceilometer measurements at Cabauw (The Netherlands) and lidar BLH retrievals at Trainou (France). Furthermore, we compare TM5 simulations of 222Rn activity concentrations, using a novel, process-based 222Rn flux map over Europe (Karstens et al., 2015), with quasi-continuous 222Rn measurements from 10 European monitoring stations. The TM5 model reproduces relatively well the daytime BLH (within ~ 10–20 % for most of the stations), except for coastal sites, for which differences are usually larger due to model representation errors. During night, TM5 overestimates the shallow nocturnal BLHs, especially for the very low observed BLHs ( The 222Rn activity concentration simulations based on the new 222Rn flux map show significant improvements especially regarding the average seasonal variability, compared to simulations using constant 222Rn fluxes. Nevertheless, the (relative) differences between simulated and observed daytime minimum 222Rn activity concentrations are larger for several stations (on the order of 50 %) compared to the (relative) differences between simulated and observed BLH at noon. Although the nocturnal BLH is often higher in the model than observed, simulated 222Rn nighttime maxima are larger at several continental stations, which points to potential deficiencies of TM5 to correctly simulate the vertical gradients within the nocturnal boundary layer, limitations of the 222Rn flux map, or issues related to the definition of the nocturnal BLH. At several stations the simulated decrease of 222Rn activity concentrations in the morning is faster than observed. In addition, simulated vertical 222Rn activity concentration gradients at Cabauw decrease faster than observations during the morning transition period, and are in general lower than observed gradients during daytime, which points to too fast vertical mixing in the TM5 boundary layer during daytime. Furthermore, the capability of the TM5 model to simulate the diurnal BLH cycle is limited due to the current coarse temporal resolution (3 hr/6 hr) of the TM5 input meteorology. Additionally, we analyze the impact of a new treatment of convection in TM5, based on the ECMWF reanalysis, leading to overall significantly lower (on the order of ~ 20 %) surface 222Rn activity concentrations during daytime compared to the current default convection scheme based on Tiedtke (1989). However, the performance of the model simulations compared to the 222Rn observations is very similar in terms of root mean square and correlation coefficient for both convection schemes. ER - TY - JOUR T1 - Nitrogen balance of a boreal Scots pine forest A1 - Korhonen, J. F. J. A1 - Pihlatie, M. A1 - Pumpanen, J. A1 - Aaltonen, H. A1 - Hari, P. A1 - Levula, J. A1 - Kieloaho, A.-J. A1 - Nikinmaa, E. A1 - Vesala, T. A1 - Ilvesniemi, H. Y1 - 2013/02// JF - Biogeosciences VL - 10 IS - 2 SP - 1083 EP - 1095 DO - 10.5194/bg-10-1083-2013 UR - http://www.biogeosciences.net/10/1083/2013/ ER - TY - JOUR T1 - Measurements of methane emission from a temperate wetland by the eddy covariance method A1 - Kowalska, N. A1 - Chojnicki, B.H. A1 - Rinne, J. A1 - Haapanala, S. A1 - Siedlecki, P. A1 - Urbaniak, M. A1 - Juszczak, R. A1 - Olejnik, J. Y1 - 2013/01// JF - International Agrophysics VL - 27 IS - 3 DO - 10.2478/v10247-012-0096-5 UR - http://www.degruyter.com/view/j/intag.2013.27.issue-3/v10247-012-0096-5/v10247-012-0096-5.xml ER - TY - JOUR T1 - Impact of optimized mixing heights on simulated regional atmospheric transport of CO2 A1 - Kretschmer, R. A1 - Gerbig, C. A1 - Karstens, U. A1 - Biavati, G. A1 - Vermeulen, A. A1 - Vogel, F. A1 - Hammer, S. A1 - Totsche, K. U. Y1 - 2014/07// JF - Atmospheric Chemistry and Physics VL - 14 IS - 14 SP - 7149 EP - 7172 DO - 10.5194/acp-14-7149-2014 UR - http://www.atmos-chem-phys.net/14/7149/2014/ N2 - The mixing height (MH) is a crucial parameter in commonly used transport models that proportionally affects air concentrations of trace gases with sources/sinks near the ground and on diurnal scales. Past synthetic data experiments indicated the possibility to improve tracer transport by minimizing errors of simulated MHs. In this paper we evaluate a method to constrain the Lagrangian particle dispersion model STILT (Stochastic Time-Inverted Lagrangian Transport) with MH diagnosed from radiosonde profiles using a bulk Richardson method. The same method was used to obtain hourly MHs for the period September/October 2009 from the Weather Research and Forecasting (WRF) model, which covers the European continent at 10 km horizontal resolution. Kriging with external drift (KED) was applied to estimate optimized MHs from observed and modelled MHs, which were used as input for STILT to assess the impact on CO2 transport. Special care has been taken to account for uncertainty in MH retrieval in this estimation process. MHs and CO2 concentrations were compared to vertical profiles from aircraft in situ data. We put an emphasis on testing the consistency of estimated MHs to observed vertical mixing of CO2. Modelled CO2 was also compared with continuous measurements made at Cabauw and Heidelberg stations. WRF MHs were significantly biased by ~10–20% during day and ~40–60% during night. Optimized MHs reduced this bias to ~5% with additional slight improvements in random errors. The KED MHs were generally more consistent with observed CO2 mixing. The use of optimized MHs had in general a favourable impact on CO2 transport, with bias reductions of 5–45% (day) and 60–90% (night). This indicates that a large part of the found CO2 model–data mismatch was indeed due to MH errors. Other causes for CO2 mismatch are discussed. Applicability of our method is discussed in the context of CO2 inversions at regional scales. ER - TY - JOUR T1 - Changes in biogeochemistry and carbon fluxes in a boreal forest after the clear-cutting and partial burning of slash A1 - Kulmala, Liisa A1 - Aaltonen, Hermanni A1 - Berninger, Frank A1 - Kieloaho, Antti-Jussi A1 - Levula, Janne A1 - Bäck, Jaana A1 - Hari, Pertti A1 - Kolari, Pasi A1 - Korhonen, Janne F.J. A1 - Kulmala, Markku A1 - Nikinmaa, Eero A1 - Pihlatie, Mari A1 - Vesala, Timo A1 - Pumpanen, Jukka Y1 - 2014/05// JF - Agricultural and Forest Meteorology VL - 188 SP - 33 EP - 44 DO - 10.1016/j.agrformet.2013.12.003 UR - http://linkinghub.elsevier.com/retrieve/pii/S0168192313003146 ER - TY - JOUR T1 - Frozen ponds: production and storage of methane during the Arctic winter in a lowland tundra landscape in northern Siberia, Lena River delta A1 - Langer, M. A1 - Westermann, S. A1 - Walter Anthony, K. A1 - Wischnewski, K. A1 - Boike, J. Y1 - 2015/02// JF - Biogeosciences VL - 12 IS - 4 SP - 977 EP - 990 DO - 10.5194/bg-12-977-2015 UR - http://www.biogeosciences.net/12/977/2015/ N2 - Lakes and ponds play a key role in the carbon cycle of permafrost ecosystems, where they are considered to be hotspots of carbon dioxide CO2 and methane CH4 emission. The strength of these emissions is, however, controlled by a variety of physical and biogeochemical processes whose responses to a warming climate are complex and only poorly understood. Small waterbodies have been attracting an increasing amount of attention since recent studies demonstrated that ponds can make a significant contribution to the CO2 and CH4emissions of tundra ecosystems. Waterbodies also have a marked effect on the thermal state of the surrounding permafrost; during the freezing period they prolong the period of time during which thawed soil material is available for microbial decomposition. This study presents net CH4 production rates during the freezing period from ponds within a typical lowland tundra landscape in northern Siberia. Rate estimations were based on CH4 concentrations measured in surface lake ice from a variety of waterbody types. Vertical profiles along ice blocks showed an exponential increase in CH4 concentration with depth. These CH4 profiles were reproduced by a 1-D mass balance model and the net CH4 production rates were then inferred through inverse modeling. Results revealed marked differences in early winter net CH4 production among various ponds. Ponds situated within intact polygonal ground structures yielded low net production rates, of the order of 10-11 to 10-10 mol m-2 s-1 (0.01 to 0.14 mgCH4 m-2 day-1). In contrast, ponds exhibiting clear signs of erosion yielded net CH4 production rates of the order of 10-7 mol m-2 s-1 (140 mg CH4 m-2 day-1). Our results therefore indicate that once a particular threshold in thermal erosion has been crossed, ponds can develop into major CH4 sources. This implies that any future warming of the climate may result in nonlinear CH4 emission behavior in tundra ecosystems. ER - TY - JOUR T1 - Newly detected ozone-depleting substances in the atmosphere A1 - Laube, Johannes C. A1 - Newland, Mike J. A1 - Hogan, Christopher A1 - Brenninkmeijer, Carl A. M. A1 - Fraser, Paul J. A1 - Martinerie, Patricia A1 - Oram, David E. A1 - Reeves, Claire E. A1 - Röckmann, Thomas A1 - Schwander, Jakob A1 - Witrant, Emmanuel A1 - Sturges, William T. Y1 - 2014/03// JF - Nature Geoscience VL - 7 IS - 4 SP - 266 EP - 269 DO - 10.1038/ngeo2109 UR - http://www.nature.com/doifinder/10.1038/ngeo2109 ER - TY - JOUR T1 - Comparison of nitrous oxide (N2O) analyzers for high-precision measurements of atmospheric mole fractions A1 - Lebegue, B. A1 - Schmidt, M. A1 - Ramonet, M. A1 - Wastine, B. A1 - Yver Kwok, C. A1 - Laurent, O. A1 - Belviso, S. A1 - Guemri, A. A1 - Philippon, C. A1 - Smith, J. A1 - Conil, S. A1 - Jost, H. J. A1 - Crosson, E. R. Y1 - 2015/10// JF - Atmospheric Measurement Techniques Discussions VL - 8 IS - 10 SP - 10937 EP - 10982 DO - 10.5194/amtd-8-10937-2015 UR - http://www.atmos-meas-tech-discuss.net/8/10937/2015/ N2 - Over the last few decades, in-situ measurements of atmospheric N2O mole fractions have been performed using gas chromatographs (GCs) equipped with electron capture detectors (ECDs). When trying to meet the World Meteorological Organization's (WMO) quality goal, this technique becomes very challenging as the detectors are highly non-linear and the GCs at remote stations require a considerable amount of maintenance by qualified technicians to maintain good short-term and long-term repeatability. With more robust optical spectrometers being now available for N2O measurements, we aim to identify a robust and stable analyzer that can be integrated into atmospheric monitoring networks, such as the Integrated Carbon Observation System (ICOS). In this study, we tested seven analyzers that were developed and commercialized from five different companies and compared the results with established techniques. Each instrument was characterized during a time period of approximately eight weeks. The test protocols included the characterization of the short-term and long-term repeatability, drift, temperature dependence, linearity and sensitivity to water vapor. During the test period, ambient air measurements were compared under field conditions at the Gif-sur-Yvette station. All of the analyzers showed a standard deviation better than 0.1 ppb for the 10 min averages. Some analyzers would benefit from improvements in temperature stability to reduce the instrument drift, which could then help in reducing the frequency of calibrations. For most instruments, the water vapor correction algorithms applied by companies are not sufficient for high-precision atmospheric measurements, which results in the need to dry the ambient air prior to analysis. ER - TY - JOUR T1 - Assessment of 222Radon progeny loss in long tubing based on static filter measurements in the laboratory and in the field A1 - Levin, Ingeborg A1 - Schmithüsen, Dominik A1 - Vermeulen, Alex Y1 - 2016/06// PB - Copernicus Publications JF - Atmospheric Measurement Techniques Discussions VL - 2016 SP - 1 EP - 15 DO - 10.5194/amt-2016-112 UR - http://www.atmos-meas-tech-discuss.net/amt-2016-112/ UR - http://www.atmos-meas-tech-discuss.net/amt-2016-112/amt-2016-112.pdf N2 - Aerosol loss in air intake systems potentially hampers the application of one-filter systems for progeny-based atmospheric 222Radon (222Rn) measurements. The artefacts are significant when air has to be collected via long sampling lines, e.g. from elevated heights at tall tower observatories. Here we present results from a study, determining 222Rn progeny loss from ambient air sampled via 8.2 mm inner diameter (ID) Decabon tubing (laboratory test) and from pre-installed 10 mm ID tubing at the Cabauw meteorological tower in the Netherlands. Progeny loss increased exponentially with length of the tubing, decreasing sampling efficiency to 66 % for 8.2 mm ID rolled-up tubing of 200 m length. Theoretical estimation of the loss yielded a sampling efficiency of 64 % for the same tubing, when taking into account turbulent inertial deposition of aerosol to the walls as well as loss due to gravitational settling. At Cabauw tower, theoretical estimates of the loss in vertical tubing with 10 mm ID and 200 m lengths yielded a total efficiency of 75 %, while we observed a slightly smaller sampling efficiency of 73 %. 222Rn progeny loss increased strongly at activity concentrations below 1 Bq m−3. Based on our experiments, an empirical correction function for 222Rn progeny measurements when sampling through long Decabon tubing was developed, allowing correction of respective measurements with an estimated uncertainty of 10–20 % for activity concentrations above 1 Bq m−3 and less than 10 % for activity concentrations above 2 Bq m−3. ER - TY - JOUR T1 - Long-lived atmospheric trace gases measurements in flask samples from three stations in India A1 - Lin, X. A1 - Indira, N. K. A1 - Ramonet, M. A1 - Delmotte, M. A1 - Ciais, P. A1 - Bhatt, B. C. A1 - Reddy, M. V. A1 - Angchuk, D. A1 - Balakrishnan, S. A1 - Jorphail, S. A1 - Dorjai, T. A1 - Mahey, T. T. A1 - Patnaik, S. A1 - Begum, M. A1 - Brenninkmeijer, C. A1 - Durairaj, S. A1 - Kirubagaran, R. A1 - Schmidt, M. A1 - Swathi, P. S. A1 - Vinithkumar, N. V. A1 - Yver Kwok, C. A1 - Gaur, V. K. Y1 - 2015/09// JF - Atmospheric Chemistry and Physics VL - 15 IS - 17 SP - 9819 EP - 9849 DO - 10.5194/acp-15-9819-2015 UR - http://www.atmos-chem-phys.net/15/9819/2015/ N2 - With the rapid growth in population and economic development, emissions of greenhouse gases (GHGs) from the Indian subcontinent have sharply increased during recent decades. However, evaluation of regional fluxes of GHGs and characterization of their spatial and temporal variations by atmospheric inversions remain uncertain due to a sparse regional atmospheric observation network. As a result of an Indo-French collaboration, three new atmospheric stations were established in India at Hanle (HLE), Pondicherry (PON) and Port Blair (PBL), with the objective of monitoring the atmospheric concentrations of GHGs and other trace gases. Here we present the results of the measurements of CO2, CH4, N2O, SF6, CO, and H2 from regular flask sampling at these three stations over the period 2007–2011. For each species, annual means, seasonal cycles and gradients between stations were calculated and related to variations in natural GHG fluxes, anthropogenic emissions, and monsoon circulations. Covariances between species at the synoptic scale were analyzed to investigate the likely source(s) of emissions. The flask measurements of various trace gases at the three stations have the potential to constrain the inversions of fluxes over southern and northeastern India. However, this network of ground stations needs further extension to other parts of India to better constrain the GHG budgets at regional and continental scales. ER - TY - JOUR T1 - Does GOSAT capture the true seasonal cycle of carbon dioxide? A1 - Lindqvist, H. A1 - O'Dell, C. W. A1 - Basu, S. A1 - Boesch, H. A1 - Chevallier, F. A1 - Deutscher, N. A1 - Feng, L. A1 - Fisher, B. A1 - Hase, F. A1 - Inoue, M. A1 - Kivi, R. A1 - Morino, I. A1 - Palmer, P. I. A1 - Parker, R. A1 - Schneider, M. A1 - Sussmann, R. A1 - Yoshida, Y. Y1 - 2015/11// JF - Atmospheric Chemistry and Physics VL - 15 IS - 22 SP - 13023 EP - 13040 DO - 10.5194/acp-15-13023-2015 UR - http://www.atmos-chem-phys.net/15/13023/2015/ N2 - The seasonal cycle accounts for a dominant mode of total column CO2 (XCO2) annual variability and is connected to CO2 uptake and release; it thus represents an important quantity to test the accuracy of the measurements from space. We quantitatively evaluate the XCO2 seasonal cycle of the Greenhouse Gases Observing Satellite (GOSAT) observations from the Atmospheric CO2 Observations from Space (ACOS) retrieval system and compare average regional seasonal cycle features to those directly measured by the Total Carbon Column Observing Network (TCCON). We analyse the mean seasonal cycle amplitude, dates of maximum and minimum XCO2, as well as the regional growth rates in XCO2 through the fitted trend over several years. We find that GOSAT/ACOS captures the seasonal cycle amplitude within 1.0 ppm accuracy compared to TCCON, except in Europe, where the difference exceeds 1.0 ppm at two sites, and the amplitude captured by GOSAT/ACOS is generally shallower compared to TCCON. This bias over Europe is not as large for the other GOSAT retrieval algorithms (NIES v02.21, RemoTeC v2.35, UoL v5.1, and NIES PPDF-S v.02.11), although they have significant biases at other sites. We find that the ACOS bias correction partially explains the shallow amplitude over Europe. The impact of the co-location method and aerosol changes in the ACOS algorithm were also tested and found to be few tenths of a ppm and mostly non-systematic. We find generally good agreement in the date of minimum XCO2 between ACOS and TCCON, but ACOS generally infers a date of maximum XCO2 2–3 weeks later than TCCON. We further analyse the latitudinal dependence of the seasonal cycle amplitude throughout the Northern Hemisphere and compare the dependence to that predicted by current optimized models that assimilate in situ measurements of CO2. In the zonal averages, models are consistent with the GOSAT amplitude to within 1.4 ppm, depending on the model and latitude. We also show that the seasonal cycle of XCO2 depends on longitude especially at the mid-latitudes: the amplitude of GOSAT XCO2 doubles from western USA to East Asia at 45–50° N, which is only partially shown by the models. In general, we find that model-to-model differences can be larger than GOSAT-to-model differences. These results suggest that GOSAT/ACOS retrievals of the XCO2 seasonal cycle may be sufficiently accurate to evaluate land surface models in regions with significant discrepancies between the models. ER - TY - JOUR T1 - Atmospheric transport and chemistry of trace gases in LMDz5B: evaluation and implications for inverse modelling A1 - Locatelli, R. A1 - Bousquet, P. A1 - Hourdin, F. A1 - Saunois, M. A1 - Cozic, A. A1 - Couvreux, F. A1 - Grandpeix, J.-Y. A1 - Lefebvre, M.-P. A1 - Rio, C. A1 - Bergamaschi, P. A1 - Chambers, S. D. A1 - Karstens, U. A1 - Kazan, V. A1 - van der Laan, S. A1 - Meijer, H. A. J. A1 - Moncrieff, J. A1 - Ramonet, M. A1 - Scheeren, H. A. A1 - Schlosser, C. A1 - Schmidt, M. A1 - Vermeulen, A. A1 - Williams, A. G. Y1 - 2015/02// JF - Geoscientific Model Development VL - 8 IS - 2 SP - 129 EP - 150 DO - 10.5194/gmd-8-129-2015 UR - http://www.geosci-model-dev.net/8/129/2015/ N2 - Representation of atmospheric transport is a major source of error in the estimation of greenhouse gas sources and sinks by inverse modelling. Here we assess the impact on trace gas mole fractions of the new physical parameterizations recently implemented in the atmospheric global climate model LMDz to improve vertical diffusion, mesoscale mixing by thermal plumes in the planetary boundary layer (PBL), and deep convection in the troposphere. At the same time, the horizontal and vertical resolution of the model used in the inverse system has been increased. The aim of this paper is to evaluate the impact of these developments on the representation of trace gas transport and chemistry, and to anticipate the implications for inversions of greenhouse gas emissions using such an updated model. Comparison of a one-dimensional version of LMDz with large eddy simulations shows that the thermal scheme simulates shallow convective tracer transport in the PBL over land very efficiently, and much better than previous versions of the model. This result is confirmed in three-dimensional simulations, by a much improved reproduction of the radon-222 diurnal cycle. However, the enhanced dynamics of tracer concentrations induces a stronger sensitivity of the new LMDz configuration to external meteorological forcings. At larger scales, the inter-hemispheric exchange is slightly slower when using the new version of the model, bringing them closer to observations. The increase in the vertical resolution (from 19 to 39 layers) significantly improves the representation of stratosphere/troposphere exchange. Furthermore, changes in atmospheric thermodynamic variables, such as temperature, due to changes in the PBL mixing modify chemical reaction rates, which perturb chemical equilibriums of reactive trace gases. One implication of LMDz model developments for future inversions of greenhouse gas emissions is the ability of the updated system to assimilate a larger amount of high-frequency data sampled at high-variability stations. Others implications are discussed at the end of the paper. ER - TY - JOUR T1 - Three years of semicontinuous greenhouse gas measurements at the Puy de Dôme station (central France) A1 - Lopez, M. A1 - Schmidt, M. A1 - Ramonet, M. A1 - Bonne, J.-L. A1 - Colomb, A. A1 - Kazan, V. A1 - Laj, P. A1 - Pichon, J.-M. Y1 - 2015/09// JF - Atmospheric Measurement Techniques VL - 8 IS - 9 SP - 3941 EP - 3958 DO - 10.5194/amt-8-3941-2015 UR - http://www.atmos-meas-tech.net/8/3941/2015/ N2 - Three years of greenhouse gas measurements, obtained using a gas chromatograph (GC) system located at the Puy de Dôme station at 1465 m a.s.l. in central France, are presented. The GC system was installed in 2010 at Puy de Dôme and was designed for automatic and accurate semicontinuous measurements of atmospheric carbon dioxide, methane, nitrous oxide and sulfur hexafluoride mole fractions. We present in detail the instrumental setup and the calibration strategy, which together allow the GC to reach repeatabilities of 0.1 μmol mol−1, 1.2 nmol mol−1, 0.3 nmol mol−1 and 0.06 pmol mol−1 for CO2, CH4, N2O and SF6, respectively. The analysis of the 3-year atmospheric time series revealed how the planetary boundary layer height drives the mole fractions observed at a mountain site such as Puy de Dôme where air masses alternate between the planetary boundary layer and the free troposphere. Accurate long-lived greenhouse gas measurements collocated with 222Rn measurements as an atmospheric tracer allowed us to determine the CO2, CH4 and N2O emissions in the catchment area of the station. The derived CO2 surface flux revealed a clear seasonal cycle, with net uptake by plant assimilation in the spring and net emission caused by the biosphere and burning of fossil fuel during the remainder of the year. We calculated a mean annual CO2 flux of 1310 ± 680 t CO2 km−2. The derived CH4 and N2O emissions in the station catchment area were 7.0 ± 4.0 t CH4 km−2 yr−1 and 1.8 ± 1.0 t N2O km−2 yr−1, respectively. Our derived annual CH4 flux is in agreement with the national French inventory, whereas our derived N2O flux is 5 times larger than the same inventory. ER - TY - JOUR T1 - Investigating discrepancies in heat, CO2 fluxes and O3 deposition velocity over maize as measured by the eddy-covariance and the aerodynamic gradient methods A1 - Loubet, Benjamin A1 - Cellier, Pierre A1 - Fléchard, Christophe A1 - Zurfluh, Olivier A1 - Irvine, Mark A1 - Lamaud, Eric A1 - Stella, Patrick A1 - Roche, Romain A1 - Durand, Brigitte A1 - Flura, Dominique A1 - Masson, Sylvie A1 - Laville, Patricia A1 - Garrigou, Didier A1 - Personne, Erwan A1 - Chelle, Michael A1 - Castell, Jean-François Y1 - 2013/02// JF - Agricultural and Forest Meteorology VL - 169 SP - 35 EP - 50 DO - 10.1016/j.agrformet.2012.09.010 UR - http://linkinghub.elsevier.com/retrieve/pii/S0168192312002845 ER - TY - JOUR T1 - Reconciling reported and unreported HFC emissions with atmospheric observations A1 - Lunt, Mark F. A1 - Rigby, Matthew A1 - Ganesan, Anita L. A1 - Manning, Alistair J. A1 - Prinn, Ronald G. A1 - O’Doherty, Simon A1 - Mühle, Jens A1 - Harth, Christina M. A1 - Salameh, Peter K. A1 - Arnold, Tim A1 - Weiss, Ray F. A1 - Saito, Takuya A1 - Yokouchi, Yoko A1 - Krummel, Paul B. A1 - Steele, L. Paul A1 - Fraser, Paul J. A1 - Li, Shanlan A1 - Park, Sunyoung A1 - Reimann, Stefan A1 - Vollmer, Martin K. A1 - Lunder, Chris A1 - Hermansen, Ove A1 - Schmidbauer, Norbert A1 - Maione, Michela A1 - Arduini, Jgor A1 - Young, Dickon A1 - Simmonds, Peter G. Y1 - 2015/05// JF - Proceedings of the National Academy of Sciences VL - 112 IS - 19 SP - 5927 EP - 5931 DO - 10.1073/pnas.1420247112 UR - http://www.pnas.org/lookup/doi/10.1073/pnas.1420247112 ER - TY - JOUR T1 - Effects of soil temperature and moisture on methane uptake and nitrous oxide emissions across three different ecosystem types A1 - Luo, G. J. A1 - Kiese, R. A1 - Wolf, B. A1 - Butterbach-Bahl, K. Y1 - 2013/05// JF - Biogeosciences VL - 10 IS - 5 SP - 3205 EP - 3219 DO - 10.5194/bg-10-3205-2013 UR - http://www.biogeosciences.net/10/3205/2013/ ER - TY - JOUR T1 - Regional CO2 flux estimates for 2009–2010 based on GOSAT and ground-based CO2 observations A1 - Maksyutov, S. A1 - Takagi, H. A1 - Valsala, V. K. A1 - Saito, M. A1 - Oda, T. A1 - Saeki, T. A1 - Belikov, D. A. A1 - Saito, R. A1 - Ito, A. A1 - Yoshida, Y. A1 - Morino, I. A1 - Uchino, O. A1 - Andres, R. J. A1 - Yokota, T. Y1 - 2013/09// JF - Atmospheric Chemistry and Physics VL - 13 IS - 18 SP - 9351 EP - 9373 DO - 10.5194/acp-13-9351-2013 UR - http://www.atmos-chem-phys.net/13/9351/2013/ ER - TY - JOUR T1 - EddyUH: an advanced software package for eddy covariance flux calculation for a wide range of instrumentation and ecosystems A1 - Mammarella, I. A1 - Peltola, O. A1 - Nordbo, A. A1 - Järvi, L. A1 - Rannik, Ü. Y1 - 2016/01// JF - Atmospheric Measurement Techniques Discussions SP - 1 EP - 33 DO - 10.5194/amt-2015-323 UR - http://www.atmos-meas-tech-discuss.net/amt-2015-323/ N2 - We have carried out an inter-comparison between EddyUH and EddyPro®, two public software packages for post-field processing of eddy covariance data. Datasets including carbon dioxide, methane and water vapour fluxes measured over two months at a wetland in Southern Finland and carbon dioxide and water vapour fluxes measured over three months at an urban site in Helsinki, were processed and analysed. The purpose was to estimate the flux uncertainty due to the use of different software packages and to evaluate the most critical processing steps, determining the largest deviations in the calculated fluxes. Turbulent fluxes calculated with a reference combination of processing steps were in good agreement, the systematic difference between the two software packages being up to 2% and 6.7% for half-hour and cumulative sum values, respectively. The raw data preparation and processing steps were consistent between the software packages, and most of the deviations in the estimated fluxes were due to the flux corrections. Among the different calculation procedures analysed, the spectral correction had biggest impact for closed-path latent heat fluxes, reaching nocturnal median value of 15% at the wetland site. We found up to 43% median value of deviation (with respect to the run with all corrections included) if closed path carbon dioxide flux is calculated without the dilution correction, while the methane fluxes were up to 10% lower without both dilution and spectroscopic corrections. The density (and spectroscopic) correction was the most critical step for open-path systems. However, we found also large spectral correction factors for the open-path methane fluxes, due to the sensor separation effect. ER - TY - JOUR T1 - Carbon dioxide and energy fluxes over a small boreal lake in Southern Finland A1 - Mammarella, Ivan A1 - Nordbo, Annika A1 - Rannik, Üllar A1 - Haapanala, Sami A1 - Levula, Janne A1 - Laakso, Heikki A1 - Ojala, Anne A1 - Peltola, Olli A1 - Heiskanen, Jouni A1 - Pumpanen, Jukka A1 - Vesala, Timo Y1 - 2015/07// JF - Journal of Geophysical Research: Biogeosciences VL - 120 IS - 7 SP - 1296 EP - 1314 DO - 10.1002/2014JG002873 UR - http://doi.wiley.com/10.1002/2014JG002873 ER - TY - JOUR T1 - Radon flux maps for the Netherlands and Europe using terrestrial gamma radiation derived from soil radionuclides A1 - Manohar, S.N. A1 - Meijer, H.A.J. A1 - Herber, M.A. Y1 - 2013/12// JF - Atmospheric Environment VL - 81 SP - 399 EP - 412 DO - 10.1016/j.atmosenv.2013.09.005 UR - http://linkinghub.elsevier.com/retrieve/pii/S1352231013006936 ER - TY - JOUR T1 - Nitrous oxide and methane in two tropical estuaries in a peat-dominated region of North-western Borneo A1 - Müller, D. A1 - Bange, H. W. A1 - Warneke, T. A1 - Rixen, T. A1 - Müller, M. A1 - Mujahid, A. A1 - Notholt, J. Y1 - 2016/01// JF - Biogeosciences Discussions SP - 1 EP - 28 DO - 10.5194/bg-2016-4 UR - http://www.biogeosciences-discuss.net/bg-2016-4/ N2 - Estuaries are sources of nitrous oxide (N2O) and methane (CH4) to the atmosphere. However, our present knowledge of N2O and CH4 emissions from estuaries in the tropics is very limited because data is scarce. In this study, we present first measurements of dissolved N2O and CH4 from two estuaries in a peat-dominated region of north-western Borneo. Two campaigns (during the dry seaso n in June 2013 and during the wet season in March 2014) were conducted in the estuaries of the rivers Lupar and Saribas. Median N2O concentrations ranged between 7.2 and 12.3 nmol L-1and were higher in the marine end-member (13.0 ± 7.0 nmol L-1). CH4 concentrations were low in the coastal ocean (3.6 ± 0.2 nmol L-1) and higher in the estuaries (medians between 12.2 and 64.0 nmol L-1). The respiration of abundant organic matter and presumably anthropogenic input caused a slight eutrophication, which did not lead to hypoxia or enhanced N2O concentrations, however. Generally, N2O concentrations were not related to dissolved inorganic nitrogen concentrations. Thus, the use of an emission factor for the calculation of N2O emissions from the inorganic nitrogen load leads to an overestimation of the flux from the Lupar and Saribas estuaries. N2O was negatively correlated with salinity during the dry season, which suggests a riverine source. In contrast, N2O concentrations during the wet season were not correlated with salinity but locally enhanced within the estuaries, implying that there were additional estuarine sources during the wet (i.e. monsoon) season. Estuarine CH4 distributions were not driven by freshwater input but rather by tidal variations. Both N2O and CH4 concentrations were more variable during the wet season. We infer that the wet season dominates the variability of the N2O and CH4 concentrations and subsequent emissions from tropical estuaries. Thus, we speculate that any changes the Southeast Asian monsoon system will lead to changes in the N2O and CH4 emissions from these systems. We also suggest that the ongoing cultivation of peat soil in Borneo is likely to increase N2O emissions from these estuaries, while the effect on CH4 remains uncertain. ER - TY - JOUR T1 - Fate of terrestrial organic carbon and associated CO2 and CO emissions from two Southeast Asian estuaries A1 - Müller, D. A1 - Warneke, T. A1 - Rixen, T. A1 - Müller, M. A1 - Mujahid, A. A1 - Bange, H. W. A1 - Notholt, J. Y1 - 2016/02// JF - Biogeosciences VL - 13 IS - 3 SP - 691 EP - 705 DO - 10.5194/bg-13-691-2016 UR - http://www.biogeosciences.net/13/691/2016/ N2 - Southeast Asian rivers convey large amounts of organic carbon, but little is known about the fate of this terrestrial material in estuaries. Although Southeast Asia is, by area, considered a hotspot of estuarine carbon dioxide (CO2) emissions, studies in this region are very scarce. We measured dissolved and particulate organic carbon, as well as CO2 partial pressures and carbon monoxide (CO) concentrations in two tropical estuaries in Sarawak, Malaysia, whose coastal area is covered by carbon-rich peatlands. We surveyed the estuaries of the rivers Lupar and Saribas during the wet and dry season, respectively. Carbon-to-nitrogen ratios suggest that dissolved organic matter (DOM) is largely of terrestrial origin. We found evidence that a large fraction of this carbon is respired. The median pCO2 in the estuaries ranged between 640 and 5065 µatm with little seasonal variation. CO2 fluxes were determined with a floating chamber and estimated to amount to 14–268 mol m−2 yr−1, which is high compared to other studies from tropical and subtropical sites. Estimates derived from a merely wind-driven turbulent diffusivity model were considerably lower, indicating that these models might be inappropriate in estuaries, where tidal currents and river discharge make an important contribution to the turbulence driving water–air gas exchange. Although an observed diurnal variability of CO concentrations suggested that CO was photochemically produced, the overall concentrations and fluxes were relatively moderate (0.4–1.3 nmol L−1 and 0.7–1.8 mmol m−2 yr−1) if compared to published data for oceanic or upwelling systems. We attributed this to the large amounts of suspended matter (4–5004 mg L−1), limiting the light penetration depth and thereby inhibiting CO photoproduction. We concluded that estuaries in this region function as an efficient filter for terrestrial organic carbon and release large amounts of CO2 to the atmosphere. The Lupar and Saribas rivers deliver 0.3 ± 0.2 Tg C yr−1 to the South China Sea as organic carbon and their mid-estuaries release approximately 0.4 ± 0.2 Tg C yr−1 into the atmosphere as CO2. ER - TY - JOUR T1 - Permafrost collapse after shrub removal shifts tundra ecosystem to a methane source A1 - Nauta, Ake L. A1 - Heijmans, Monique M. P. D. A1 - Blok, Daan A1 - Limpens, Juul A1 - Elberling, Bo A1 - Gallagher, Angela A1 - Li, Bingxi A1 - Petrov, Roman E. A1 - Maximov, Trofim C. A1 - van Huissteden, Jacobus A1 - Berendse, Frank Y1 - 2014/11// JF - Nature Climate Change VL - 5 IS - 1 SP - 67 EP - 70 DO - 10.1038/nclimate2446 UR - http://www.nature.com/doifinder/10.1038/nclimate2446 ER - TY - JOUR T1 - Regional Representativeness of CH4 and N2O Mixing Ratio Measurements at High-Altitude Mountain Station Kasprowy Wierch, Southern Poland A1 - Nęcki, Jarosław M. A1 - Gałkowski, Michał A1 - Chmura, Łukasz A1 - Gerbig, Christoph A1 - Zimnoch, Mirosław A1 - Zięba, Damian A1 - Bartyzel, Jakub A1 - Wołkowicz, Wojciech A1 - Różański, Kazimierz Y1 - 2016/// JF - Aerosol and Air Quality Research VL - 16 IS - 3 SP - 568 EP - 580 DO - 10.4209/aaqr.2015.05.0357 UR - http://aaqr.org/Doi.php?id=9_AAQR-15-05-SIMtS-0357&v=16&i=3&m=3&y=2016 ER - TY - JOUR T1 - Methane on the Rise--Again A1 - Nisbet, E. G. A1 - Dlugokencky, E. J. A1 - Bousquet, P. Y1 - 2014/01// JF - Science VL - 343 IS - 6170 SP - 493 EP - 495 DO - 10.1126/science.1247828 UR - http://www.sciencemag.org/cgi/doi/10.1126/science.1247828 ER - TY - JOUR T1 - An automated gas chromatography time-of-flight mass spectrometry instrument for the quantitative analysis of halocarbons in air A1 - Obersteiner, F. A1 - Bönisch, H. A1 - Engel, A. Y1 - 2016/01// JF - Atmospheric Measurement Techniques VL - 9 IS - 1 SP - 179 EP - 194 DO - 10.5194/amt-9-179-2016 UR - http://www.atmos-meas-tech.net/9/179/2016/ N2 - We present the characterization and application of a new gas chromatography time-of-flight mass spectrometry instrument (GC-TOFMS) for the quantitative analysis of halocarbons in air samples. The setup comprises three fundamental enhancements compared to our earlier work (Hoker et al., 2015): (1) full automation, (2) a mass resolving power R = m/Δm of the TOFMS (Tofwerk AG, Switzerland) increased up to 4000 and (3) a fully accessible data format of the mass spectrometric data. Automation in combination with the accessible data allowed an in-depth characterization of the instrument. Mass accuracy was found to be approximately 5 ppm in mean after automatic recalibration of the mass axis in each measurement. A TOFMS configuration giving R = 3500 was chosen to provide an R-to-sensitivity ratio suitable for our purpose. Calculated detection limits are as low as a few femtograms by means of the accurate mass information. The precision for substance quantification was 0.15 % at the best for an individual measurement and in general mainly determined by the signal-to-noise ratio of the chromatographic peak. Detector non-linearity was found to be insignificant up to a mixing ratio of roughly 150 ppt at 0.5 L sampled volume. At higher concentrations, non-linearities of a few percent were observed (precision level: 0.2 %) but could be attributed to a potential source within the detection system. A straightforward correction for those non-linearities was applied in data processing, again by exploiting the accurate mass information. Based on the overall characterization results, the GC-TOFMS instrument was found to be very well suited for the task of quantitative halocarbon trace gas observation and a big step forward compared to scanning, quadrupole MS with low mass resolving power and a TOFMS technique reported to be non-linear and restricted by a small dynamical range. ER - TY - JOUR T1 - Global emissions of HFC-143a (CH3CF3) and HFC-32 (CH2F2) from in situ and air archive atmospheric observations A1 - O'Doherty, S. A1 - Rigby, M. A1 - Mühle, J. A1 - Ivy, D. J. A1 - Miller, B. R. A1 - Young, D. A1 - Simmonds, P. G. A1 - Reimann, S. A1 - Vollmer, M. K. A1 - Krummel, P. B. A1 - Fraser, P. J. A1 - Steele, L. P. A1 - Dunse, B. A1 - Salameh, P. K. A1 - Harth, C. M. A1 - Arnold, T. A1 - Weiss, R. F. A1 - Kim, J. A1 - Park, S. A1 - Li, S. A1 - Lunder, C. A1 - Hermansen, O. A1 - Schmidbauer, N. A1 - Zhou, L. X. A1 - Yao, B. A1 - Wang, R. H. J. A1 - Manning, A. J. A1 - Prinn, R. G. Y1 - 2014/09// JF - Atmospheric Chemistry and Physics VL - 14 IS - 17 SP - 9249 EP - 9258 DO - 10.5194/acp-14-9249-2014 UR - http://www.atmos-chem-phys.net/14/9249/2014/ N2 - High-frequency, in situ observations from the Advanced Global Atmospheric Gases Experiment (AGAGE), for the period 2003 to 2012, combined with archive flask measurements dating back to 1977, have been used to capture the rapid growth of HFC-143a (CH3CF3) and HFC-32 (CH2F2) mole fractions and emissions into the atmosphere. Here we report the first in situ global measurements of these two gases. HFC-143a and HFC-32 are the third and sixth most abundant hydrofluorocarbons (HFCs) respectively and they currently make an appreciable contribution to the HFCs in terms of atmospheric radiative forcing (1.7 ± 0.04 and 0.7 ± 0.02 mW m−2 in 2012 respectively). In 2012 the global average mole fraction of HFC-143a was 13.4 ± 0.3 ppt (1σ) in the lower troposphere and its growth rate was 1.4 ± 0.04 ppt yr−1; HFC-32 had a global mean mole fraction of 6.2 ± 0.2 ppt and a growth rate of 1.1 ± 0.04 ppt yr−1 in 2012. The extensive observations presented in this work have been combined with an atmospheric transport model to simulate global atmospheric abundances and derive global emission estimates. It is estimated that 23 ± 3 Gg yr−1 of HFC-143a and 21 ± 11 Gg yr−1 of HFC-32 were emitted globally in 2012, and the emission rates are estimated to be increasing by 7 ± 5% yr−1 for HFC-143a and 14 ± 11% yr−1 for HFC-32. ER - TY - JOUR T1 - Long-term tropospheric trend of octafluorocyclobutane (c-C4F8 or PFC-318) A1 - Oram, D. E. A1 - Mani, F. S. A1 - Laube, J. C. A1 - Newland, M. J. A1 - Reeves, C. E. A1 - Sturges, W. T. A1 - Penkett, S. A. A1 - Brenninkmeijer, C. A. M. A1 - Röckmann, T. A1 - Fraser, P. J. Y1 - 2012/01// JF - Atmospheric Chemistry and Physics VL - 12 IS - 1 SP - 261 EP - 269 DO - 10.5194/acp-12-261-2012 UR - http://www.atmos-chem-phys.net/12/261/2012/ ER - TY - JOUR T1 - Effects of atmospheric light scattering on spectroscopic observations of greenhouse gases from space: Validation of PPDF-based CO 2 retrievals from GOSAT A1 - Oshchepkov, Sergey A1 - Bril, Andrey A1 - Yokota, Tatsuya A1 - Morino, Isamu A1 - Yoshida, Yukio A1 - Matsunaga, Tsuneo A1 - Belikov, Dmitry A1 - Wunch, Debra A1 - Wennberg, Paul A1 - Toon, Geoffrey A1 - O'Dell, Christopher A1 - Butz, André A1 - Guerlet, Sandrine A1 - Cogan, Austin A1 - Boesch, Hartmut A1 - Eguchi, Nawo A1 - Deutscher, Nicholas A1 - Griffith, David A1 - Macatangay, Ronald A1 - Notholt, Justus A1 - Sussmann, Ralf A1 - Rettinger, Markus A1 - Sherlock, Vanessa A1 - Robinson, John A1 - Kyrö, Esko A1 - Heikkinen, Pauli A1 - Feist, Dietrich G. A1 - Nagahama, Tomoo A1 - Kadygrov, Nikolay A1 - Maksyutov, Shamil A1 - Uchino, Osamu A1 - Watanabe, Hiroshi Y1 - 2012/06// JF - Journal of Geophysical Research: Atmospheres VL - 117 IS - D12 SP - n/a EP - n/a DO - 10.1029/2012JD017505 UR - http://doi.wiley.com/10.1029/2012JD017505 ER - TY - JOUR T1 - Effects of atmospheric light scattering on spectroscopic observations of greenhouse gases from space. Part 2: Algorithm intercomparison in the GOSAT data processing for CO 2 retrievals over TCCON sites A1 - Oshchepkov, Sergey A1 - Bril, Andrey A1 - Yokota, Tatsuya A1 - Wennberg, Paul O. A1 - Deutscher, Nicholas M. A1 - Wunch, Debra A1 - Toon, Geoffrey C. A1 - Yoshida, Yukio A1 - O'Dell, Christopher W. A1 - Crisp, David A1 - Miller, Charles E. A1 - Frankenberg, Christian A1 - Butz, André A1 - Aben, Ilse A1 - Guerlet, Sandrine A1 - Hasekamp, Otto A1 - Boesch, Hartmut A1 - Cogan, Austin A1 - Parker, Robert A1 - Griffith, David A1 - Macatangay, Ronald A1 - Notholt, Justus A1 - Sussmann, Ralf A1 - Rettinger, Markus A1 - Sherlock, Vanessa A1 - Robinson, John A1 - Kyrö, Esko A1 - Heikkinen, Pauli A1 - Feist, Dietrich G. A1 - Morino, Isamu A1 - Kadygrov, Nikolay A1 - Belikov, Dmitry A1 - Maksyutov, Shamil A1 - Matsunaga, Tsuneo A1 - Uchino, Osamu A1 - Watanabe, Hiroshi Y1 - 2013/02// JF - Journal of Geophysical Research: Atmospheres VL - 118 IS - 3 SP - 1493 EP - 1512 DO - 10.1002/jgrd.50146 UR - http://doi.wiley.com/10.1002/jgrd.50146 ER - TY - JOUR T1 - Simultaneous retrieval of atmospheric CO_2 and light path modification from space-based spectroscopic observations of greenhouse gases: methodology and application to GOSAT measurements over TCCON sites A1 - Oshchepkov, Sergey A1 - Bril, Andrey A1 - Yokota, Tatsuya A1 - Yoshida, Yukio A1 - Blumenstock, Thomas A1 - Deutscher, Nicholas M. A1 - Dohe, Susanne A1 - Macatangay, Ronald A1 - Morino, Isamu A1 - Notholt, Justus A1 - Rettinger, Markus A1 - Petri, Christof A1 - Schneider, Matthias A1 - Sussman, Ralf A1 - Uchino, Osamu A1 - Velazco, Voltaire A1 - Wunch, Debra A1 - Belikov, Dmitry Y1 - 2013/02// JF - Applied Optics VL - 52 IS - 6 SP - 1339 EP - 1339 DO - 10.1364/AO.52.001339 UR - https://www.osapublishing.org/abstract.cfm?URI=ao-52-6-1339 ER - TY - JOUR T1 - Development of a cavity-enhanced absorption spectrometer for airborne measurements of CH4 and CO2 A1 - O'Shea, S. J. A1 - Bauguitte, S. J.-B. A1 - Gallagher, M. W. A1 - Lowry, D. A1 - Percival, C. J. Y1 - 2013/05// JF - Atmospheric Measurement Techniques VL - 6 IS - 5 SP - 1095 EP - 1109 DO - 10.5194/amt-6-1095-2013 UR - http://www.atmos-meas-tech.net/6/1095/2013/ ER - TY - JOUR T1 - Area fluxes of carbon dioxide, methane, and carbon monoxide derived from airborne measurements around Greater London: A case study during summer 2012 A1 - O'Shea, Sebastian J. A1 - Allen, Grant A1 - Fleming, Zoë L. A1 - Bauguitte, Stephane J.-B. A1 - Percival, Carl J. A1 - Gallagher, Martin W. A1 - Lee, James A1 - Helfter, Carole A1 - Nemitz, Eiko Y1 - 2014/04// JF - Journal of Geophysical Research: Atmospheres VL - 119 IS - 8 SP - 4940 EP - 4952 DO - 10.1002/2013JD021269 UR - http://doi.wiley.com/10.1002/2013JD021269 ER - TY - JOUR T1 - The imprint of stratospheric transport on column-averaged methane A1 - Ostler, A. A1 - Sussmann, R. A1 - Patra, P. K. A1 - Wennberg, P. O. A1 - Deutscher, N. M. A1 - Griffith, D. W. T. A1 - Blumenstock, T. A1 - Hase, F. A1 - Kivi, R. A1 - Warneke, T. A1 - Wang, Z. A1 - De Mazière, M. A1 - Robinson, J. A1 - Ohyama, H. Y1 - 2015/07// JF - Atmospheric Chemistry and Physics Discussions VL - 15 IS - 14 SP - 20395 EP - 20447 DO - 10.5194/acpd-15-20395-2015 UR - http://www.atmos-chem-phys-discuss.net/15/20395/2015/ N2 - Model simulations of column-averaged methane mixing ratios (XCH4) are extensively used for inverse estimates of methane (CH4) emissions from atmospheric measurements. Our study shows that virtually all chemical transport models (CTM) used for this purpose are affected by stratospheric model-transport errors. We quantify the impact of such model transport errors on the simulation of stratospheric CH4 concentrations via an a posteriori correction method. This approach compares measurements of the mean age of air with modeled age and expresses the difference in terms of a correction to modeled stratospheric CH4 mixing ratios. We find age differences up to ~ 3 years yield to a bias in simulated CH4 of up to 250 parts per billion (ppb). Comparisons between model simulations and ground-based XCH4 observations from the Total Carbon Column Network (TCCON) reveal that stratospheric model-transport errors cause biases in XCH4 of ~ 20 ppb in the midlatitudes and ~ 27 ppb in the arctic region. Improved overall as well as seasonal model-observation agreement in XCH4 suggests that the proposed, age-of-air-based stratospheric correction is reasonable. The latitudinal model bias in XCH4 is supposed to reduce the accuracy of inverse estimates using satellite-derived XCH4 data. Therefore, we provide an estimate of the impact of stratospheric model-transport errors in terms of CH4 flux errors. Using a one-box approximation, we show that average model errors in stratospheric transport correspond to an overestimation of CH4 emissions by ~ 40 % (~ 7 Tg yr−1) for the arctic, ~ 5 % (~ 7 Tg yr−1) for the northern, and ~ 60 % (~ 7 Tg yr−1) for the southern hemispheric mid-latitude region. We conclude that an improved modeling of stratospheric transport is highly desirable for the joint use with atmospheric XCH4 observations in atmospheric inversions. ER - TY - JOUR T1 - Multistation intercomparison of column-averaged methane from NDACC and TCCON: impact of dynamical variability A1 - Ostler, A. A1 - Sussmann, R. A1 - Rettinger, M. A1 - Deutscher, N. M. A1 - Dohe, S. A1 - Hase, F. A1 - Jones, N. A1 - Palm, M. A1 - Sinnhuber, B.-M. Y1 - 2014/12// JF - Atmospheric Measurement Techniques VL - 7 IS - 12 SP - 4081 EP - 4101 DO - 10.5194/amt-7-4081-2014 UR - http://www.atmos-meas-tech.net/7/4081/2014/ N2 - Dry-air column-averaged mole fractions of methane (XCH4) retrieved from ground-based solar Fourier transform infrared (FTIR) measurements provide valuable information for satellite validation, evaluation of chemical-transport models, and source-sink-inversions. In this context, Sussmann et al. (2013) have shown that midinfrared (MIR) soundings from the Network for the Detection of Atmospheric Composition Change (NDACC) can be combined with near-infrared (NIR) soundings from the Total Carbon Column Observing Network (TCCON) without the need to apply an overall intercalibration factor. However, in spite of efforts to reduce a priori impact, some residual seasonal biases were identified, and the reasons behind remained unclear. In extension to this previous work, which was based on multiannual quasi-coincident MIR and NIR measurements from the stations Garmisch (47.48° N, 11.06° E, 743 m a.s.l.) and Wollongong (34.41° S, 150.88° E, 30 m a.s.l.), we now investigate upgraded retrievals with longer temporal coverage and include three additional stations (Ny-Ålesund, 78.92° N, 11.93° E, 20 m a.s.l.; Karlsruhe, 49.08° N, 8.43° E, 110 m a.s.l.; Izaña, 28.31° N, 16.45° W, 2.370 m a.s.l.). Our intercomparison results (except for Ny-Ålesund) confirm that there is no overall bias between MIR and NIR XCH4 retrievals, and all MIR and NIR time series reveal a quasi-periodic seasonal bias for all stations, except for Izaña. We find that dynamical variability causes MIR–NIR differences of up to ~ 30 ppb (parts per billion) for Ny-Ålesund, ~ 20 ppb for Wollongong, ~ 18 ppb for Garmisch, and ~ 12 ppb for Karlsruhe. The mechanisms behind this variability are elaborated via two case studies, one dealing with stratospheric subsidence induced by the polar vortex at Ny-Ålesund and the other with a deep stratospheric intrusion event at Garmisch. Smoothing effects caused by the dynamical variability during these events are different for MIR and NIR retrievals depending on the altitude of the perturbation area. MIR retrievals appear to be more realistic in the case of stratospheric subsidence, while NIR retrievals are more accurate in the case of stratosphere–troposphere exchange (STE) in the upper troposphere/lower stratosphere (UTLS) region. About 35% of the FTIR measurement days at Garmisch are impacted by STE, and about 23% of the measurement days at Ny-Ålesund are influenced by polar vortex subsidence. The exclusion of data affected by these dynamical situations resulted in improved agreement of MIR and NIR seasonal cycles for Ny-Ålesund and Garmisch. We found that dynamical variability is a key factor in constraining the accuracy of MIR and NIR seasonal cycles. To mitigate this impact it is necessary to use more realistic a priori profiles that take these dynamical events into account (e.g., via improved models), and/or to improve the FTIR retrievals to achieve a more uniform sensitivity at all altitudes (possibly including profile retrievals for the TCCON data). ER - TY - JOUR T1 - Investigation of the atmospheric boundary layer depth variability and its impact on the 222 Rn concentration at a rural site in France A1 - Pal, S. A1 - Lopez, M. A1 - Schmidt, M. A1 - Ramonet, M. A1 - Gibert, F. A1 - Xueref-Remy, I. A1 - Ciais, P. Y1 - 2015/01// JF - Journal of Geophysical Research: Atmospheres VL - 120 IS - 2 SP - 623 EP - 643 DO - 10.1002/2014JD022322 UR - http://doi.wiley.com/10.1002/2014JD022322 ER - TY - JOUR T1 - Assessing 5 years of GOSAT Proxy XCH4 data and associated uncertainties A1 - Parker, R. J. A1 - Boesch, H. A1 - Byckling, K. A1 - Webb, A. J. A1 - Palmer, P. I. A1 - Feng, L. A1 - Bergamaschi, P. A1 - Chevallier, F. A1 - Notholt, J. A1 - Deutscher, N. A1 - Warneke, T. A1 - Hase, F. A1 - Sussmann, R. A1 - Kawakami, S. A1 - Kivi, R. A1 - Griffith, D. W. T. A1 - Velazco, V. Y1 - 2015/11// JF - Atmospheric Measurement Techniques VL - 8 IS - 11 SP - 4785 EP - 4801 DO - 10.5194/amt-8-4785-2015 UR - http://www.atmos-meas-tech.net/8/4785/2015/ N2 - We present 5 years of GOSAT XCH4 retrieved using the "proxy" approach. The Proxy XCH4 data are validated against ground-based TCCON observations and are found to be of high quality with a small bias of 4.8 ppb (∼ 0.27 %) and a single-sounding precision of 13.4 ppb (∼ 0.74 %). The station-to-station bias (ameasure of the relative accuracy) is found to be 4.2 ppb. For the first time the XCH4 / XCO2 ratio component of the Proxy retrieval is validated (bias of 0.014 ppb ppm−1 (∼ 0.30 %), single-sounding precision of 0.033 ppb ppm−1 (∼ 0.72 %)). The uncertainty relating to the model XCO2 component of the Proxy XCH4 is assessed through the use of an ensemble of XCO2 models. While each individual XCO2 model is found to agree well with the TCCON validation data (r = 0.94–0.97), it is not possible to select one model as the best from our comparisons. The median XCO2 value of the ensemble has a smaller scatter against TCCON (a standard deviation of 0.92 ppm) than any of the individual models whilst maintaining a small bias (0.15 ppm). This model median XCO2 is used to calculate the Proxy XCH4 with the maximum deviation of the ensemble from the median used as an estimate of the uncertainty. We compare this uncertainty to the a posteriori retrieval error (which is assumed to reduce with sqrt(N)) and find typically that the model XCO2 uncertainty becomes significant during summer months when the a posteriori error is at its lowest due to the increase in signal related to increased summertime reflected sunlight. We assess the significance of these model and retrieval uncertainties on flux inversion by comparing the GOSAT XCH4 against modelled XCH4 from TM5-4DVAR constrained by NOAA surface observations (MACC reanalysis scenario S1-NOAA). We find that for the majority of regions the differences are much larger than the estimated uncertainties. Our findings show that useful information will be provided to the inversions for the majority of regions in addition to that already provided by the assimilated surface measurements. ER - TY - JOUR T1 - Cross-Validation of a Mobile N2O Flux Prototype (IPNOA) Using Micrometeorological and Chamber Methods A1 - Patricia Laville A1 - Simone Neri A1 - David Continanza A1 - Luca Ferrante Vero A1 - Simona Bosco A1 - Giorgio Virgili Y1 - 2015/04// JF - Journal of Energy and Power Engineering VL - 9 IS - 4 DO - 10.17265/1934-8975/2015.04.007 UR - http://www.davidpublisher.org/index.php/Home/Article/index?id=7863.html ER - TY - JOUR T1 - Studying the spatial variability of methane flux with five eddy covariance towers of varying height A1 - Peltola, O. A1 - Hensen, A. A1 - Belelli Marchesini, L. A1 - Helfter, C. A1 - Bosveld, F.C. A1 - van den Bulk, W.C.M. A1 - Haapanala, S. A1 - van Huissteden, J. A1 - Laurila, T. A1 - Lindroth, A. A1 - Nemitz, E. A1 - Röckmann, T. A1 - Vermeulen, A.T. A1 - Mammarella, I. Y1 - 2015/12// JF - Agricultural and Forest Meteorology VL - 214-215 SP - 456 EP - 472 DO - 10.1016/j.agrformet.2015.09.007 UR - http://linkinghub.elsevier.com/retrieve/pii/S0168192315007121 ER - TY - JOUR T1 - Evaluating the performance of commonly used gas analysers for methane eddy covariance flux measurements: the InGOS inter-comparison field experiment A1 - Peltola, O. A1 - Hensen, A. A1 - Helfter, C. A1 - Belelli Marchesini, L. A1 - Bosveld, F. C. A1 - van den Bulk, W. C. M. A1 - Elbers, J. A. A1 - Haapanala, S. A1 - Holst, J. A1 - Laurila, T. A1 - Lindroth, A. A1 - Nemitz, E. A1 - Röckmann, T. A1 - Vermeulen, A. T. A1 - Mammarella, I. Y1 - 2014/06// JF - Biogeosciences VL - 11 IS - 12 SP - 3163 EP - 3186 DO - 10.5194/bg-11-3163-2014 UR - http://www.biogeosciences.net/11/3163/2014/ N2 - The performance of eight fast-response methane (CH4) gas analysers suitable for eddy covariance flux measurements were tested at a grassland site near the Cabauw tall tower (Netherlands) during June 2012. The instruments were positioned close to each other in order to minimise the effect of varying turbulent conditions. The moderate CH4 fluxes observed at the location, of the order of 25 nmol m−2 s−1, provided a suitable signal for testing the instruments' performance. Generally, all analysers tested were able to quantify the concentration fluctuations at the frequency range relevant for turbulent exchange and were able to deliver high-quality data. The tested cavity ringdown spectrometer (CRDS) instruments from Picarro, models G2311-f and G1301-f, were superior to other CH4 analysers with respect to instrumental noise. As an open-path instrument susceptible to the effects of rain, the LI-COR LI-7700 achieved lower data coverage and also required larger density corrections; however, the system is especially useful for remote sites that are restricted in power availability. In this study the open-path LI-7700 results were compromised due to a data acquisition problem in our data-logging setup. Some of the older closed-path analysers tested do not measure H2O concentrations alongside CH4 (i.e. FMA1 and DLT-100 by Los Gatos Research) and this complicates data processing since the required corrections for dilution and spectroscopic interactions have to be based on external information. To overcome this issue, we used H2O mole fractions measured by other gas analysers, adjusted them with different methods and then applied them to correct the CH4 fluxes. Following this procedure we estimated a bias of the order of 0.1 g (CH4) m−2 (8% of the measured mean flux) in the processed and corrected CH4 fluxes on a monthly scale due to missing H2O concentration measurements. Finally, cumulative CH4 fluxes over 14 days from three closed-path gas analysers, G2311-f (Picarro Inc.), FGGA (Los Gatos Research) and FMA2 (Los Gatos Research), which were measuring H2O concentrations in addition to CH4, agreed within 3% (355–367 mg (CH4) m−2) and were not clearly different from each other, whereas the other instruments derived total fluxes which showed small but distinct differences (±10%, 330–399 mg (CH4) m−2). ER - TY - JOUR T1 - Field intercomparison of four methane gas analyzers suitable for eddy covariance flux measurements A1 - Peltola, O. A1 - Mammarella, I. A1 - Haapanala, S. A1 - Burba, G. A1 - Vesala, T. Y1 - 2013/06// JF - Biogeosciences VL - 10 IS - 6 SP - 3749 EP - 3765 DO - 10.5194/bg-10-3749-2013 UR - http://www.biogeosciences.net/10/3749/2013/ ER - TY - JOUR T1 - Investigating sources and sinks for ammonia exchanges between the atmosphere and a wheat canopy following slurry application with trailing hose A1 - Personne, Erwan A1 - Tardy, Florence A1 - Génermont, Sophie A1 - Decuq, Céline A1 - Gueudet, Jean-Christophe A1 - Mascher, Nicolas A1 - Durand, Brigitte A1 - Masson, Sylvie A1 - Lauransot, Michel A1 - Fléchard, Christophe A1 - Burkhardt, Jürgen A1 - Loubet, Benjamin Y1 - 2015/07// JF - Agricultural and Forest Meteorology VL - 207 SP - 11 EP - 23 DO - 10.1016/j.agrformet.2015.03.002 UR - http://linkinghub.elsevier.com/retrieve/pii/S0168192315000805 ER - TY - JOUR T1 - The uncertain climate footprint of wetlands under human pressure A1 - Petrescu, Ana Maria Roxana A1 - Lohila, Annalea A1 - Tuovinen, Juha-Pekka A1 - Baldocchi, Dennis D. A1 - Desai, Ankur R. A1 - Roulet, Nigel T. A1 - Vesala, Timo A1 - Dolman, Albertus Johannes A1 - Oechel, Walter C. A1 - Marcolla, Barbara A1 - Friborg, Thomas A1 - Rinne, Janne A1 - Matthes, Jaclyn Hatala A1 - Merbold, Lutz A1 - Meijide, Ana A1 - Kiely, Gerard A1 - Sottocornola, Matteo A1 - Sachs, Torsten A1 - Zona, Donatella A1 - Varlagin, Andrej A1 - Lai, Derrick Y. F. A1 - Veenendaal, Elmar A1 - Parmentier, Frans-Jan W. A1 - Skiba, Ute A1 - Lund, Magnus A1 - Hensen, Arjan A1 - van Huissteden, Jacobus A1 - Flanagan, Lawrence B. A1 - Shurpali, Narasinha J. A1 - Grünwald, Thomas A1 - Humphreys, Elyn R. A1 - Jackowicz-Korczyński, Marcin A1 - Aurela, Mika A. A1 - Laurila, Tuomas A1 - Grüning, Carsten A1 - Corradi, Chiara A. R. A1 - Schrier-Uijl, Arina P. A1 - Christensen, Torben R. A1 - Tamstorf, Mikkel P. A1 - Mastepanov, Mikhail A1 - Martikainen, Pertti J. A1 - Verma, Shashi B. A1 - Bernhofer, Christian A1 - Cescatti, Alessandro Y1 - 2015/04// JF - Proceedings of the National Academy of Sciences VL - 112 IS - 15 SP - 4594 EP - 4599 DO - 10.1073/pnas.1416267112 UR - http://www.pnas.org/lookup/doi/10.1073/pnas.1416267112 ER - TY - JOUR T1 - Remote sensing of CO2 and CH4 using solar absorption spectrometry with a low resolution spectrometer A1 - Petri, C. A1 - Warneke, T. A1 - Jones, N. A1 - Ridder, T. A1 - Messerschmidt, J. A1 - Weinzierl, T. A1 - Geibel, M. A1 - Notholt, J. Y1 - 2012/07// JF - Atmospheric Measurement Techniques VL - 5 IS - 7 SP - 1627 EP - 1635 DO - 10.5194/amt-5-1627-2012 UR - http://www.atmos-meas-tech.net/5/1627/2012/ ER - TY - JOUR T1 - Reassessing the variability in atmospheric H 2 using the two-way nested TM5 model A1 - Pieterse, G. A1 - Krol, M. C. A1 - Batenburg, A. M. A1 - M. Brenninkmeijer, C. A. A1 - Popa, M. E. A1 - O'Doherty, S. A1 - Grant, A. A1 - Steele, L. P. A1 - Krummel, P. B. A1 - Langenfelds, R. L. A1 - Wang, H. J. A1 - Vermeulen, A. T. A1 - Schmidt, M. A1 - Yver, C. A1 - Jordan, A. A1 - Engel, A. A1 - Fisher, R. E. A1 - Lowry, D. A1 - Nisbet, E. G. A1 - Reimann, S. A1 - Vollmer, M. K. A1 - Steinbacher, M. A1 - Hammer, S. A1 - Forster, G. A1 - Sturges, W. T. A1 - Röckmann, T. Y1 - 2013/05// JF - Journal of Geophysical Research: Atmospheres VL - 118 IS - 9 SP - 3764 EP - 3780 DO - 10.1002/jgrd.50204 UR - http://doi.wiley.com/10.1002/jgrd.50204 ER - TY - JOUR T1 - Seasonal and diurnal variation in CO fluxes from an agricultural bioenergy crop A1 - Pihlatie, M. A1 - Rannik, Ü. A1 - Haapanala, S. A1 - Peltola, O. A1 - Shurpali, N. A1 - Martikainen, P. J. A1 - Lind, S. A1 - Hyvönen, N. A1 - Virkajärvi, P. A1 - Zahniser, M. A1 - Mammarella, I. Y1 - 2016/01// JF - Biogeosciences Discussions SP - 1 EP - 27 DO - 10.5194/bg-2015-622 UR - http://www.biogeosciences-discuss.net/bg-2015-622/ N2 - Carbon monoxide (CO) is an important reactive trace gas in the atmosphere, while its sources and sinks in the biosphere are only poorly understood. Emissions of CO have been reported from a wide range of soil-plant systems. However, soils are generally considered as a sink of CO due to microbial oxidation processes. We measured CO fluxes by micrometeorological eddy covariance method from a bioenergy crop (reed canary grass) in Eastern Finland over April to November 2011. Continuous flux measurements allowed us to assess the seasonal and diurnal variability, and to compare the CO fluxes to simultaneously measured CO2, N2O and heat fluxes as well as relevant meteorological, soil and plant variables in order to investigate factors driving the CO exchange. The reed canary grass crop was a net source of CO from mid-April to mid-June, and a net sink throughout the rest of the measurement period from July to November 2011. CO fluxes had a distinct diurnal pattern with a net CO uptake in the night and an emission during the daytime with a maximum emission at noon. This pattern was most pronounced during the spring and early summer, during which the most significant relationships were found between daytime CO fluxes and global radiation, net radiation, sensible heat flux, soil heat flux, relative humidity and net ecosystem exchange. The strong positive correlation between CO fluxes and radiation suggests towards abiotic CO production processes, whereas, the relationship of CO fluxes with net ecosystem exchange indicates towards biotic CO formation during crop growth. The study shows a clear need for detailed process-studies accompanied with continuous flux measurements of CO exchange to improve the understanding of the processes associated with CO exchange. ER - TY - JOUR T1 - Multilayer modelling of ozone fluxes on winter wheat reveals large deposition on wet senescing leaves A1 - Potier, E. A1 - Ogée, J. A1 - Jouanguy, J. A1 - Lamaud, E. A1 - Stella, P. A1 - Personne, E. A1 - Durand, B. A1 - Mascher, N. A1 - Loubet, B. Y1 - 2015/10// JF - Agricultural and Forest Meteorology VL - 211-212 SP - 58 EP - 71 DO - 10.1016/j.agrformet.2015.05.006 UR - http://linkinghub.elsevier.com/retrieve/pii/S0168192315001483 ER - TY - JOUR T1 - Precipitation and net ecosystem exchange are the most important drivers of DOC flux in upland boreal catchments A1 - Pumpanen, Jukka A1 - Lindén, Aki A1 - Miettinen, Heli A1 - Kolari, Pasi A1 - Ilvesniemi, Hannu A1 - Mammarella, Ivan A1 - Hari, Pertti A1 - Nikinmaa, Eero A1 - Heinonsalo, Jussi A1 - Bäck, Jaana A1 - Ojala, Anne A1 - Berninger, Frank A1 - Vesala, Timo Y1 - 2014/09// JF - Journal of Geophysical Research: Biogeosciences VL - 119 IS - 9 SP - 1861 EP - 1878 DO - 10.1002/2014JG002705 UR - http://doi.wiley.com/10.1002/2014JG002705 ER - TY - JOUR T1 - Intercomparison of fast response commercial gas analysers for nitrous oxide flux measurements under field conditions A1 - Rannik, Ü. A1 - Haapanala, S. A1 - Shurpali, N. J. A1 - Mammarella, I. A1 - Lind, S. A1 - Hyvönen, N. A1 - Peltola, O. A1 - Zahniser, M. A1 - Martikainen, P. J. A1 - Vesala, T. Y1 - 2014/08// JF - Biogeosciences Discussions VL - 11 IS - 8 SP - 11747 EP - 11783 DO - 10.5194/bgd-11-11747-2014 UR - http://www.biogeosciences-discuss.net/11/11747/2014/ N2 - Four gas analysers capable of measuring nitrous oxide (N2O) concentration at a response time necessary for eddy covariance flux measurements were operated from spring till winter 2011 over a field cultivated with reed canary grass (RCG, Phalaris arundinaceae, L.), a perennial bioenergy crop in Eastern Finland. The instruments were TGA100A (Campbell Scientific Inc.), CW-TILDAS-CS (Aerodyne Research Inc.), N2O/CO-23d (Los Gatos Research Inc.) and QC-TILDAS-76-CS (Aerodyne Research Inc.). The period with high emission, lasting for about two weeks after fertilization in late May, was characterised by an up to two orders of magnitude higher emission, whereas during the rest of the campaign the N2O fluxes were small, from 0.1 to 1 nmol m−2 s−1. Two instruments, CW-TILDAS-CS and N2O/CO-23d, determined the N2O exchange with minor systematic difference throughout the campaign, when operated simultaneously. TGA100A produced cumulatively highest N2O estimates (with 29% higher value during the period when all instruments were operational). QC-TILDAS-76-CS obtained 36% lower fluxes than CW-TILDAS-CS during the first period, including the emission episode, whereas the correspondence with other instruments during the rest of the campaign was good. The reason for these episodic higher and lower estimates by the two instruments is not currently known, suggesting further need for detailed evaluation of instrument performance under field conditions with emphasis on stability, calibration and, in particular, simultaneous accurate determination of water vapour concentration due to its large impact on small N2O fluxes through spectroscopic and dilution corrections. The instrument CW-TILDAS-CS was characterised by the lowest noise level (std around 0.12 ppb at 10 Hz sampling rate), as compared to N2O/CO-23d and QC-TILDAS-76-CS (around 0.50 ppb) and TGA100A (around 2 ppb). Both instruments based on Continuous-Wave Quantum Cascade Lasers, CW-TILDAS-CS and N2O/CO-23d, were able to determine the same sample of low N2O fluxes with high mutual coefficient of determination at 30 min averaging level and with minor systematic difference over the observation period of several months. ER - TY - JOUR T1 - Random uncertainties of flux measurements by the eddy covariance technique A1 - Rannik, Üllar A1 - Peltola, Olli A1 - Mammarella, Ivan Y1 - 2016/02// JF - Atmospheric Measurement Techniques Discussions SP - 1 EP - 31 DO - 10.5194/amt-2016-31 UR - http://www.atmos-meas-tech-discuss.net/amt-2016-31/ N2 - Large variability is inherent to turbulent flux observations. We review different methods used to estimate the flux random errors. Flux errors are calculated using measured turbulent and simulated artificial records. We recommend two flux errors with clear physical meaning: the flux error of the co-variance, defining the error of the measured flux as one standard deviation of the random uncertainty of turbulent flux observed over an averaging period of typically 30 min to 1 hour duration; and the error of the flux due to the instrumental noise. We suggest that the numerical approximation by Finkelstein and Sims (2001) is a robust and accurate method for calculation of the first error estimate. The method appeared insensitive to the integration period and the value 200 s sufficient to obtain the estimate without significant bias for variety of sites and wide range of observation conditions. The error proposed by Wienhold et al. (1995) is a good approximation to the total flux random uncertainty provided that independent cross-covariance values far from the maximum are used in estimation as suggested in this study. For the error due to instrumental noise the method by Lenschow et al. (2000) is useful in evaluation of the respective uncertainty. The method was found to be reliable for signal-to-noise ratio, defined by the ratio of the standard deviation of the signal to that of the noise in this study, less than three. Finally, the random uncertainty of the error estimates was determined to be in the order of 10 to 30 % for the total flux error depending on the conditions and method of estimation. ER - TY - JOUR T1 - Different Apparent Gas Exchange Coefficients for CO 2 and CH 4 : Comparing a Brown-Water and a Clear-Water Lake in the Boreal Zone during the Whole Growing Season A1 - Rantakari, Miitta A1 - Heiskanen, Jouni A1 - Mammarella, Ivan A1 - Tulonen, Tiina A1 - Linnaluoma, Jessica A1 - Kankaala, Paula A1 - Ojala, Anne Y1 - 2015/10// JF - Environmental Science & Technology VL - 49 IS - 19 SP - 11388 EP - 11394 DO - 10.1021/acs.est.5b01261 UR - http://pubs.acs.org/doi/10.1021/acs.est.5b01261 ER - TY - JOUR T1 - High accuracy measurements of dry mole fractions of carbon dioxide and methane in humid air A1 - Rella, C. W. A1 - Chen, H. A1 - Andrews, A. E. A1 - Filges, A. A1 - Gerbig, C. A1 - Hatakka, J. A1 - Karion, A. A1 - Miles, N. L. A1 - Richardson, S. J. A1 - Steinbacher, M. A1 - Sweeney, C. A1 - Wastine, B. A1 - Zellweger, C. Y1 - 2013/03// JF - Atmospheric Measurement Techniques VL - 6 IS - 3 SP - 837 EP - 860 DO - 10.5194/amt-6-837-2013 UR - http://www.atmos-meas-tech.net/6/837/2013/ ER - TY - JOUR T1 - Satellite-inferred European carbon sink larger than expected A1 - Reuter, M. A1 - Buchwitz, M. A1 - Hilker, M. A1 - Heymann, J. A1 - Schneising, O. A1 - Pillai, D. A1 - Bovensmann, H. A1 - Burrows, J. P. A1 - Bösch, H. A1 - Parker, R. A1 - Butz, A. A1 - Hasekamp, O. A1 - O'Dell, C. W. A1 - Yoshida, Y. A1 - Gerbig, C. A1 - Nehrkorn, T. A1 - Deutscher, N. M. A1 - Warneke, T. A1 - Notholt, J. A1 - Hase, F. A1 - Kivi, R. A1 - Sussmann, R. A1 - Machida, T. A1 - Matsueda, H. A1 - Sawa, Y. Y1 - 2014/12// JF - Atmospheric Chemistry and Physics VL - 14 IS - 24 SP - 13739 EP - 13753 DO - 10.5194/acp-14-13739-2014 UR - http://www.atmos-chem-phys.net/14/13739/2014/ N2 - Current knowledge about the European terrestrial biospheric carbon sink, from the Atlantic to the Urals, relies upon bottom-up inventory and surface flux inverse model estimates (e.g. 0.27±0.16 GtC a−1 for 2000–2005 (Schulze et al., 2009), 0.17±0.44 GtC a−1 for 2001–2007 (Peters et al., 2010), 0.45±0.40 GtC a−1 for 2010 (Chevallier et al., 2014), 0.40±0.42 GtC a−1 for 2001–2004 (Peylin et al., 2013)). Inverse models assimilate in situ CO2 atmospheric concentrations measured by surface-based air sampling networks. The intrinsic sparseness of these networks is one reason for the relatively large flux uncertainties (Peters et al., 2010; Bruhwiler et al., 2011). Satellite-based CO2 measurements have the potential to reduce these uncertainties (Miller et al., 2007; Chevallier et al., 2007). Global inversion experiments using independent models and independent GOSAT satellite data products consistently derived a considerably larger European sink (1.0–1.3 GtC a−1 for 09/2009–08/2010 (Basu et al., 2013), 1.2–1.8 GtC a−1 in 2010 (Chevallier et al., 2014)). However, these results have been considered unrealistic due to potential retrieval biases and/or transport errors (Chevallier et al., 2014) or have not been discussed at all (Basu et al., 2013; Takagi et al., 2014). Our analysis comprises a regional inversion approach using STILT (Gerbig et al., 2003; Lin et al., 2003) short-range (days) particle dispersion modelling, rendering it insensitive to large-scale retrieval biases and less sensitive to long-range transport errors. We show that the satellite-derived European terrestrial carbon sink is indeed much larger (1.02±0.30 GtC a−1 in 2010) than previously expected. This is qualitatively consistent among an ensemble of five different inversion set-ups and five independent satellite retrievals (BESD (Reuter et al., 2011) 2003–2010, ACOS (O’Dell et al., 2012) 2010, UoL-FP (Cogan et al., 2012) 2010, RemoTeC (Butz et al., 2011) 2010, and NIES (Yoshida et al., 2013) 2010) using data from two different instruments (SCIAMACHY (Bovensmann et al., 1999) and GOSAT (Kuze et al., 2009)). The difference to in situ based inversions (Peylin et al., 2013), whilst large with respect to the mean reported European carbon sink (0.4 GtC a−1 for 2001–2004), is similar in magnitude to the reported uncertainty (0.42 GtC a−1). The highest gain in information is obtained during the growing season when satellite observation conditions are advantageous, a priori uncertainties are largest, and the surface sink maximises; during the dormant season, the results are dominated by the a priori. Our results provide evidence that the current understanding of the European carbon sink has to be revisited. ER - TY - JOUR T1 - Comparison of halocarbon measurements in an atmospheric dry whole air sample A1 - Rhoderick, George C. A1 - Hall, Bradley D. A1 - Harth, Christina M. A1 - Kim, Jin Seog A1 - Lee, Jeongsoon A1 - Montzka, Stephen A. A1 - Mühle, Jens A1 - Reimann, Stefan A1 - Vollmer, Martin K. A1 - Weiss, Ray F. Y1 - 2015/11// JF - Elementa: Science of the Anthropocene VL - 3 SP - 000075 EP - 000075 DO - 10.12952/journal.elementa.000075 UR - http://elementascience.org/article/info:doi/10.12952/journal.elementa.000075 ER - TY - JOUR T1 - Anthropogenic changes of CO2, CH4, N2O, CFCl3, CF2Cl2, CCl2FCClF2, CHCl3, CH3CCl3, CCl4, SF6 and SF5CF3 mixing ratios in the atmosphere over southern Poland A1 - RÓŻAŃSKI, Kazimierz A1 - NĘCKI, Jarosław A1 - CHMURA, Łukasz A1 - ŚLIWKA, Ireneusz A1 - ZIMNOCH, Mirosław A1 - BIELEWSKI, Jarosław A1 - GAŁKOWSKI, Michał A1 - BARTYZEL, Jakub A1 - ROSIEK, Janusz Y1 - 2014/04// JF - Geological Quarterly DO - 10.7306/gq.1163 UR - https://gq.pgi.gov.pl/article/view/10077/pdf_1153 ER - TY - JOUR T1 - Derivation of tropospheric methane from TCCON CH4 and HF total column observations A1 - Saad, K. M. A1 - Wunch, D. A1 - Toon, G. C. A1 - Bernath, P. A1 - Boone, C. A1 - Connor, B. A1 - Deutscher, N. M. A1 - Griffith, D. W. T. A1 - Kivi, R. A1 - Notholt, J. A1 - Roehl, C. A1 - Schneider, M. A1 - Sherlock, V. A1 - Wennberg, P. O. Y1 - 2014/09// JF - Atmospheric Measurement Techniques VL - 7 IS - 9 SP - 2907 EP - 2918 DO - 10.5194/amt-7-2907-2014 UR - http://www.atmos-meas-tech.net/7/2907/2014/ N2 - The Total Carbon Column Observing Network (TCCON) is a global ground-based network of Fourier transform spectrometers that produce precise measurements of column-averaged dry-air mole fractions of atmospheric methane (CH4). Temporal variability in the total column of CH4 due to stratospheric dynamics obscures fluctuations and trends driven by tropospheric transport and local surface fluxes that are critical for understanding CH4 sources and sinks. We reduce the contribution of stratospheric variability from the total column average by subtracting an estimate of the stratospheric CH4 derived from simultaneous measurements of hydrogen fluoride (HF). HF provides a proxy for stratospheric CH4 because it is strongly correlated to CH4 in the stratosphere, has an accurately known tropospheric abundance (of zero), and is measured at most TCCON stations. The stratospheric partial column of CH4 is calculated as a function of the zonal and annual trends in the relationship between CH4 and HF in the stratosphere, which we determine from ACE-FTS satellite data. We also explicitly take into account the CH4 column averaging kernel to estimate the contribution of stratospheric CH4 to the total column. The resulting tropospheric CH4 columns are consistent with in situ aircraft measurements and augment existing observations in the troposphere. ER - TY - JOUR T1 - Global and regional emissions estimates for N2O A1 - Saikawa, E. A1 - Prinn, R. G. A1 - Dlugokencky, E. A1 - Ishijima, K. A1 - Dutton, G. S. A1 - Hall, B. D. A1 - Langenfelds, R. A1 - Tohjima, Y. A1 - Machida, T. A1 - Manizza, M. A1 - Rigby, M. A1 - O'Doherty, S. A1 - Patra, P. K. A1 - Harth, C. M. A1 - Weiss, R. F. A1 - Krummel, P. B. A1 - van der Schoot, M. A1 - Fraser, P. J. A1 - Steele, L. P. A1 - Aoki, S. A1 - Nakazawa, T. A1 - Elkins, J. W. Y1 - 2014/05// JF - Atmospheric Chemistry and Physics VL - 14 IS - 9 SP - 4617 EP - 4641 DO - 10.5194/acp-14-4617-2014 UR - http://www.atmos-chem-phys.net/14/4617/2014/ N2 - We present a comprehensive estimate of nitrous oxide (N2O) emissions using observations and models from 1995 to 2008. High-frequency records of tropospheric N2O are available from measurements at Cape Grim, Tasmania; Cape Matatula, American Samoa; Ragged Point, Barbados; Mace Head, Ireland; and at Trinidad Head, California using the Advanced Global Atmospheric Gases Experiment (AGAGE) instrumentation and calibrations. The Global Monitoring Division of the National Oceanic and Atmospheric Administration/Earth System Research Laboratory (NOAA/ESRL) has also collected discrete air samples in flasks and in situ measurements from remote sites across the globe and analyzed them for a suite of species including N2O. In addition to these major networks, we include in situ and aircraft measurements from the National Institute of Environmental Studies (NIES) and flask measurements from the Tohoku University and Commonwealth Scientific and Industrial Research Organization (CSIRO) networks. All measurements show increasing atmospheric mole fractions of N2O, with a varying growth rate of 0.1–0.7% per year, resulting in a 7.4% increase in the background atmospheric mole fraction between 1979 and 2011. Using existing emission inventories as well as bottom-up process modeling results, we first create globally gridded a priori N2O emissions over the 37 years since 1975. We then use the three-dimensional chemical transport model, Model for Ozone and Related Chemical Tracers version 4 (MOZART v4), and a Bayesian inverse method to estimate global as well as regional annual emissions for five source sectors from 13 regions in the world. This is the first time that all of these measurements from multiple networks have been combined to determine emissions. Our inversion indicates that global and regional N2O emissions have an increasing trend between 1995 and 2008. Despite large uncertainties, a significant increase is seen from the Asian agricultural sector in recent years, most likely due to an increase in the use of nitrogenous fertilizers, as has been suggested by previous studies. ER - TY - JOUR T1 - Technical Note: Latitude-time variations of atmospheric column-average dry air mole fractions of CO2, CH4 and N2O A1 - Saito, R. A1 - Patra, P. K. A1 - Deutscher, N. A1 - Wunch, D. A1 - Ishijima, K. A1 - Sherlock, V. A1 - Blumenstock, T. A1 - Dohe, S. A1 - Griffith, D. A1 - Hase, F. A1 - Heikkinen, P. A1 - Kyrö, E. A1 - Macatangay, R. A1 - Mendonca, J. A1 - Messerschmidt, J. A1 - Morino, I. A1 - Notholt, J. A1 - Rettinger, M. A1 - Strong, K. A1 - Sussmann, R. A1 - Warneke, T. Y1 - 2012/08// JF - Atmospheric Chemistry and Physics VL - 12 IS - 16 SP - 7767 EP - 7777 DO - 10.5194/acp-12-7767-2012 UR - http://www.atmos-chem-phys.net/12/7767/2012/ ER - TY - JOUR T1 - First observations, trends, and emissions of HCFC-31 (CH 2 ClF) in the global atmosphere A1 - Schoenenberger, Fabian A1 - Vollmer, Martin K. A1 - Rigby, Matt A1 - Hill, Matthias A1 - Fraser, Paul J. A1 - Krummel, Paul B. A1 - Langenfelds, Ray L. A1 - Rhee, Tae Siek A1 - Peter, Thomas A1 - Reimann, Stefan Y1 - 2015/09// JF - Geophysical Research Letters VL - 42 IS - 18 SP - 7817 EP - 7824 DO - 10.1002/2015GL064709 UR - http://doi.wiley.com/10.1002/2015GL064709 ER - TY - JOUR T1 - Tropospheric CH4 signals as observed by NDACC FTIR at globally distributed sites and comparison to GAW surface in situ measurements A1 - Sepúlveda, E. A1 - Schneider, M. A1 - Hase, F. A1 - Barthlott, S. A1 - Dubravica, D. A1 - García, O. E. A1 - Gomez-Pelaez, A. A1 - González, Y. A1 - Guerra, J. C. A1 - Gisi, M. A1 - Kohlhepp, R. A1 - Dohe, S. A1 - Blumenstock, T. A1 - Strong, K. A1 - Weaver, D. A1 - Palm, M. A1 - Sadeghi, A. A1 - Deutscher, N. M. A1 - Warneke, T. A1 - Notholt, J. A1 - Jones, N. A1 - Griffith, D. W. T. A1 - Smale, D. A1 - Brailsford, G. W. A1 - Robinson, J. A1 - Meinhardt, F. A1 - Steinbacher, M. A1 - Aalto, T. A1 - Worthy, D. Y1 - 2014/07// JF - Atmospheric Measurement Techniques VL - 7 IS - 7 SP - 2337 EP - 2360 DO - 10.5194/amt-7-2337-2014 UR - http://www.atmos-meas-tech.net/7/2337/2014/ N2 - We present lower/middle tropospheric column-averaged CH4 mole fraction time series measured by nine globally distributed ground-based FTIR (Fourier transform infrared) remote sensing experiments of the Network for the Detection of Atmospheric Composition Change (NDACC). We show that these data are well representative of the tropospheric regional-scale CH4 signal, largely independent of the local surface small-scale signals, and only weakly dependent on upper tropospheric/lower stratospheric (UTLS) CH4 variations. In order to achieve the weak dependency on the UTLS, we use an a posteriori correction method. We estimate a typical precision for daily mean values of about 0.5% and a systematic error of about 2.5%. The theoretical assessments are complemented by an extensive empirical study. For this purpose, we use surface in situ CH4 measurements made within the Global Atmosphere Watch (GAW) network and compare them to the remote sensing data. We briefly discuss different filter methods for removing the local small-scale signals from the surface in situ data sets in order to obtain the in situ regional-scale signals. We find good agreement between the filtered in situ and the remote sensing data. The agreement is consistent for a variety of timescales that are interesting for CH4 source/sink research: day-to-day, monthly, and inter-annual. The comparison study confirms our theoretical estimations and proves that the NDACC FTIR measurements can provide valuable data for investigating the cycle of CH4. ER - TY - JOUR T1 - Surface-Parallel Sensor Orientation for Assessing Energy Balance Components on Mountain Slopes A1 - Serrano-Ortiz, P. A1 - Sánchez-Cañete, E. P. A1 - Olmo, F. J. A1 - Metzger, S. A1 - Pérez-Priego, O. A1 - Carrara, A. A1 - Alados-Arboledas, L. A1 - Kowalski, A. S. Y1 - 2016/03// JF - Boundary-Layer Meteorology VL - 158 IS - 3 SP - 489 EP - 499 DO - 10.1007/s10546-015-0099-4 UR - http://link.springer.com/10.1007/s10546-015-0099-4 ER - TY - JOUR T1 - Interannual fluctuations in the seasonal cycle of nitrous oxide and chlorofluorocarbons due to the Brewer-Dobson circulation A1 - Simmonds, P. G. A1 - Manning, A. J. A1 - Athanassiadou, M. A1 - Scaife, A. A. A1 - Derwent, R. G. A1 - O'Doherty, S. A1 - Harth, C. M. A1 - Weiss, R. F. A1 - Dutton, G. S. A1 - Hall, B. D. A1 - Sweeney, C. A1 - Elkins, J. W. Y1 - 2013/10// JF - Journal of Geophysical Research: Atmospheres VL - 118 IS - 19 SP - 10,694 EP - 10,706 DO - 10.1002/jgrd.50832 UR - http://doi.wiley.com/10.1002/jgrd.50832 ER - TY - JOUR T1 - Global and regional emissions estimates of 1,1-difluoroethane (HFC-152a, CH3CHF2) from in situ and air archive observations A1 - Simmonds, P. G. A1 - Rigby, M. A1 - Manning, A. J. A1 - Lunt, M. F. A1 - O'Doherty, S. A1 - McCulloch, A. A1 - Fraser, P. J. A1 - Henne, S. A1 - Vollmer, M. K. A1 - Mühle, J. A1 - Weiss, R. F. A1 - Salameh, P. K. A1 - Young, D. A1 - Reimann, S. A1 - Wenger, A. A1 - Arnold, T. A1 - Harth, C. M. A1 - Krummel, P. B. A1 - Steele, L. P. A1 - Dunse, B. L. A1 - Miller, B. R. A1 - Lunder, C. R. A1 - Hermansen, O. A1 - Schmidbauer, N. A1 - Saito, T. A1 - Yokouchi, Y. A1 - Park, S. A1 - Li, S. A1 - Yao, B. A1 - Zhou, L. X. A1 - Arduini, J. A1 - Maione, M. A1 - Wang, R. H. J. A1 - Ivy, D. A1 - Prinn, R. G. Y1 - 2016/01// JF - Atmospheric Chemistry and Physics VL - 16 IS - 1 SP - 365 EP - 382 DO - 10.5194/acp-16-365-2016 UR - http://www.atmos-chem-phys.net/16/365/2016/ N2 - High frequency, in situ observations from 11 globally distributed sites for the period 1994–2014 and archived air measurements dating from 1978 onward have been used to determine the global growth rate of 1,1-difluoroethane (HFC-152a, CH3CHF2). These observations have been combined with a range of atmospheric transport models to derive global emission estimates in a top-down approach. HFC-152a is a greenhouse gas with a short atmospheric lifetime of about 1.5 years. Since it does not contain chlorine or bromine, HFC-152a makes no direct contribution to the destruction of stratospheric ozone and is therefore used as a substitute for the ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). The concentration of HFC-152a has grown substantially since the first direct measurements in 1994, reaching a maximum annual global growth rate of 0.84 ± 0.05 ppt yr−1 in 2006, implying a substantial increase in emissions up to 2006. However, since 2007, the annual rate of growth has slowed to 0.38 ± 0.04 ppt yr−1 in 2010 with a further decline to an annual average rate of growth in 2013–2014 of −0.06 ± 0.05 ppt yr−1. The annual average Northern Hemisphere (NH) mole fraction in 1994 was 1.2 ppt rising to an annual average mole fraction of 10.1 ppt in 2014. Average annual mole fractions in the Southern Hemisphere (SH) in 1998 and 2014 were 0.84 and 4.5 ppt, respectively. We estimate global emissions of HFC-152a have risen from 7.3 ± 5.6 Gg yr−1 in 1994 to a maximum of 54.4 ± 17.1 Gg yr−1 in 2011, declining to 52.5 ± 20.1 Gg yr−1 in 2014 or 7.2 ± 2.8 Tg-CO2 eq yr−1. Analysis of mole fraction enhancements above regional background atmospheric levels suggests substantial emissions from North America, Asia, and Europe. Global HFC emissions (so called “bottom up” emissions) reported by the United Nations Framework Convention on Climate Change (UNFCCC) are based on cumulative national emission data reported to the UNFCCC, which in turn are based on national consumption data. There appears to be a significant underestimate ( > 20 Gg) of “bottom-up” reported emissions of HFC-152a, possibly arising from largely underestimated USA emissions and undeclared Asian emissions. ER - TY - JOUR T1 - Can seasonal and interannual variation in landscape CO2 fluxes be detected by atmospheric observations of CO2 concentrations made at a tall tower? A1 - Smallman, T. L. A1 - Williams, M. A1 - Moncrieff, J. B. Y1 - 2014/02// JF - Biogeosciences VL - 11 IS - 3 SP - 735 EP - 747 DO - 10.5194/bg-11-735-2014 UR - http://www.biogeosciences.net/11/735/2014/ ER - TY - JOUR T1 - Development and evaluation of a suite of isotope reference gases for methane in air A1 - Sperlich, P. A1 - Uitslag, N. A. M. A1 - Richter, J. M. A1 - Rothe, M. A1 - Geilmann, H. A1 - van der Veen, C. A1 - Röckmann, T. A1 - Blunier, T. A1 - Brand, W. A. Y1 - 2016/01// JF - Atmospheric Measurement Techniques Discussions SP - 1 EP - 24 DO - 10.5194/amt-2016-15 UR - http://www.atmos-meas-tech-discuss.net/amt-2016-15/ N2 - Measurements made by multiple analytical facilities can only be comparable if they are related to a unifying and traceable reference. However, reference materials that fulfil these fundamental requirements are unavailable for the analysis of isotope ratios in atmospheric methane, which led to misinterpretations of combined data sets in the past. We developed a method to produce a suite of standard gases that can be used to unify methane isotope ratio measurements of laboratories in the atmospheric monitoring community. We calibrated a suite of pure methane gases of different methanogenic origin against international referencing materials that define the VSMOW and VPDB isotope scales. The isotope ratios of our pure methane gases range between −320 and +40 ‰ for δ2H-CH4 and between −70 and −40 ‰ for δ13C-CH4, enveloping the isotope ratios of tropospheric methane (about −90 ‰ and −47 ‰ for δ2H-CH4 and δ13C-CH4, respectively). We estimate combined uncertainties for our δ2H and δ13C calibrations of <1.5 ‰ and <0.2 ‰, respectively. Aliquots of the calibrated pure methane gases have been diluted with methane-free air to atmospheric methane levels and filled into 5-L glass flasks. These synthetic gas mixtures comprise atmospheric oxygen/nitrogen ratios as well as appropriate argon, krypton and nitrous oxide mole fractions to prevent gas-specific measurement artefacts. The resulting synthetic atmospheric reference gases will be available to the atmospheric monitoring community. This will provide unifying isotope scale anchors for isotope ratio measurements of atmospheric methane so that data sets can be merged into a consistent global data frame. ER - TY - JOUR T1 - Stable carbon isotope signatures of methane from a Finnish subarctic wetland A1 - Sriskantharajah, S. A1 - Fisher, R. E. A1 - Lowry, D. A1 - Aalto, T. A1 - Hatakka, J. A1 - Aurela, M. A1 - Laurila, T. A1 - Lohila, A. A1 - Kuitunen, E. A1 - Nisbet, E. G. Y1 - 2012/06// JF - Tellus B VL - 64 IS - 0 DO - 10.3402/tellusb.v64i0.18818 UR - http://www.tellusb.net/index.php/tellusb/article/view/18818 ER - TY - JOUR T1 - Emissions halted of the potent greenhouse gas SF5CF3 A1 - Sturges, W. T. A1 - Oram, D. E. A1 - Laube, J. C. A1 - Reeves, C. E. A1 - Newland, M. J. A1 - Hogan, C. A1 - Martinerie, P. A1 - Witrant, E. A1 - Brenninkmeijer, C. A. M. A1 - Schuck, T. J. A1 - Fraser, P. J. Y1 - 2012/04// JF - Atmospheric Chemistry and Physics VL - 12 IS - 8 SP - 3653 EP - 3658 DO - 10.5194/acp-12-3653-2012 UR - http://www.atmos-chem-phys.net/12/3653/2012/ ER - TY - JOUR T1 - Upscaling of methane exchange in a boreal forest using soil chamber measurements and high-resolution LiDAR elevation data A1 - Sundqvist, E. A1 - Persson, A. A1 - Kljun, N. A1 - Vestin, P. A1 - Chasmer, L. A1 - Hopkinson, C. A1 - Lindroth, A. Y1 - 2015/12// JF - Agricultural and Forest Meteorology VL - 214-215 SP - 393 EP - 401 DO - 10.1016/j.agrformet.2015.09.003 UR - http://linkinghub.elsevier.com/retrieve/pii/S016819231500708X ER - TY - JOUR T1 - Methane exchange in a boreal forest estimated by gradient method A1 - Sundqvist, Elin A1 - Mölder, Meelis A1 - Crill, Patrick A1 - Kljun, Natascha A1 - Lindroth, Anders Y1 - 2015/07// JF - Tellus B VL - 67 IS - 0 DO - 10.3402/tellusb.v67.26688 UR - http://www.tellusb.net/index.php/tellusb/article/view/26688 ER - TY - JOUR T1 - First intercalibration of column-averaged methane from the Total Carbon Column Observing Network and the Network for the Detection of Atmospheric Composition Change A1 - Sussmann, R. A1 - Ostler, A. A1 - Forster, F. A1 - Rettinger, M. A1 - Deutscher, N. M. A1 - Griffith, D. W. T. A1 - Hannigan, J. W. A1 - Jones, N. A1 - Patra, P. K. Y1 - 2013/02// JF - Atmospheric Measurement Techniques VL - 6 IS - 2 SP - 397 EP - 418 DO - 10.5194/amt-6-397-2013 UR - http://www.atmos-meas-tech.net/6/397/2013/ ER - TY - JOUR T1 - Nitrous oxide emissions 1999 to 2009 from a global atmospheric inversion A1 - Thompson, R. L. A1 - Chevallier, F. A1 - Crotwell, A. M. A1 - Dutton, G. A1 - Langenfelds, R. L. A1 - Prinn, R. G. A1 - Weiss, R. F. A1 - Tohjima, Y. A1 - Nakazawa, T. A1 - Krummel, P. B. A1 - Steele, L. P. A1 - Fraser, P. A1 - O'Doherty, S. A1 - Ishijima, K. A1 - Aoki, S. Y1 - 2014/02// JF - Atmospheric Chemistry and Physics VL - 14 IS - 4 SP - 1801 EP - 1817 DO - 10.5194/acp-14-1801-2014 UR - http://www.atmos-chem-phys.net/14/1801/2014/ ER - TY - JOUR T1 - TransCom N2O model inter-comparison – Part 2: Atmospheric inversion estimates of N2O emissions A1 - Thompson, R. L. A1 - Ishijima, K. A1 - Saikawa, E. A1 - Corazza, M. A1 - Karstens, U. A1 - Patra, P. K. A1 - Bergamaschi, P. A1 - Chevallier, F. A1 - Dlugokencky, E. A1 - Prinn, R. G. A1 - Weiss, R. F. A1 - O'Doherty, S. A1 - Fraser, P. J. A1 - Steele, L. P. A1 - Krummel, P. B. A1 - Vermeulen, A. A1 - Tohjima, Y. A1 - Jordan, A. A1 - Haszpra, L. A1 - Steinbacher, M. A1 - Van der Laan, S. A1 - Aalto, T. A1 - Meinhardt, F. A1 - Popa, M. E. A1 - Moncrieff, J. A1 - Bousquet, P. Y1 - 2014/06// JF - Atmospheric Chemistry and Physics VL - 14 IS - 12 SP - 6177 EP - 6194 DO - 10.5194/acp-14-6177-2014 UR - http://www.atmos-chem-phys.net/14/6177/2014/ N2 - This study examines N2O emission estimates from five different atmospheric inversion frameworks based on chemistry transport models (CTMs). The five frameworks differ in the choice of CTM, meteorological data, prior uncertainties and inversion method but use the same prior emissions and observation data set. The posterior modelled atmospheric N2O mole fractions are compared to observations to assess the performance of the inversions and to help diagnose problems in the modelled transport. Additionally, the mean emissions for 2006 to 2008 are compared in terms of the spatial distribution and seasonality. Overall, there is a good agreement among the inversions for the mean global total emission, which ranges from 16.1 to 18.7 TgN yr−1 and is consistent with previous estimates. Ocean emissions represent between 31 and 38% of the global total compared to widely varying previous estimates of 24 to 38%. Emissions from the northern mid- to high latitudes are likely to be more important, with a consistent shift in emissions from the tropics and subtropics to the mid- to high latitudes in the Northern Hemisphere; the emission ratio for 0–30° N to 30–90° N ranges from 1.5 to 1.9 compared with 2.9 to 3.0 in previous estimates. The largest discrepancies across inversions are seen for the regions of South and East Asia and for tropical and South America owing to the poor observational constraint for these areas and to considerable differences in the modelled transport, especially inter-hemispheric exchange rates and tropical convective mixing. Estimates of the seasonal cycle in N2O emissions are also sensitive to errors in modelled stratosphere-to-troposphere transport in the tropics and southern extratropics. Overall, the results show a convergence in the global and regional emissions compared to previous independent studies. ER - TY - JOUR T1 - TransCom N2O model inter-comparison – Part 1: Assessing the influence of transport and surface fluxes on tropospheric N2O variability A1 - Thompson, R. L. A1 - Patra, P. K. A1 - Ishijima, K. A1 - Saikawa, E. A1 - Corazza, M. A1 - Karstens, U. A1 - Wilson, C. A1 - Bergamaschi, P. A1 - Dlugokencky, E. A1 - Sweeney, C. A1 - Prinn, R. G. A1 - Weiss, R. F. A1 - O'Doherty, S. A1 - Fraser, P. J. A1 - Steele, L. P. A1 - Krummel, P. B. A1 - Saunois, M. A1 - Chipperfield, M. A1 - Bousquet, P. Y1 - 2014/04// JF - Atmospheric Chemistry and Physics VL - 14 IS - 8 SP - 4349 EP - 4368 DO - 10.5194/acp-14-4349-2014 UR - http://www.atmos-chem-phys.net/14/4349/2014/ N2 - We present a comparison of chemistry-transport models (TransCom-N2O) to examine the importance of atmospheric transport and surface fluxes on the variability of N2O mixing ratios in the troposphere. Six different models and two model variants participated in the inter-comparison and simulations were made for the period 2006 to 2009. In addition to N2O, simulations of CFC-12 and SF6 were made by a subset of four of the models to provide information on the models' proficiency in stratosphere–troposphere exchange (STE) and meridional transport, respectively. The same prior emissions were used by all models to restrict differences among models to transport and chemistry alone. Four different N2O flux scenarios totalling between 14 and 17 TgN yr−1 (for 2005) globally were also compared. The modelled N2O mixing ratios were assessed against observations from in situ stations, discrete air sampling networks and aircraft. All models adequately captured the large-scale patterns of N2O and the vertical gradient from the troposphere to the stratosphere and most models also adequately captured the N2O tropospheric growth rate. However, all models underestimated the inter-hemispheric N2O gradient by at least 0.33 parts per billion (ppb), equivalent to 1.5 TgN, which, even after accounting for an overestimate of emissions in the Southern Ocean of circa 1.0 TgN, points to a likely underestimate of the Northern Hemisphere source by up to 0.5 TgN and/or an overestimate of STE in the Northern Hemisphere. Comparison with aircraft data reveal that the models overestimate the amplitude of the N2O seasonal cycle at Hawaii (21° N, 158° W) below circa 6000 m, suggesting an overestimate of the importance of stratosphere to troposphere transport in the lower troposphere at this latitude. In the Northern Hemisphere, most of the models that provided CFC-12 simulations captured the phase of the CFC-12, seasonal cycle, indicating a reasonable representation of the timing of STE. However, for N2O all models simulated a too early minimum by 2 to 3 months owing to errors in the seasonal cycle in the prior soil emissions, which was not adequately represented by the terrestrial biosphere model. In the Southern Hemisphere, most models failed to capture the N2O and CFC-12 seasonality at Cape Grim, Tasmania, and all failed at the South Pole, whereas for SF6, all models could capture the seasonality at all sites, suggesting that there are large errors in modelled vertical transport in high southern latitudes. ER - TY - JOUR T1 - Introduction to the European Monitoring and Evaluation Programme (EMEP) and observed atmospheric composition change during 1972&ndash;2009 A1 - Tørseth, K. A1 - Aas, W. A1 - Breivik, K. A1 - Fjæraa, A. M. A1 - Fiebig, M. A1 - Hjellbrekke, A. G. A1 - Lund Myhre, C. A1 - Solberg, S. A1 - Yttri, K. E. Y1 - 2012/06// JF - Atmospheric Chemistry and Physics VL - 12 IS - 12 SP - 5447 EP - 5481 DO - 10.5194/acp-12-5447-2012 UR - http://www.atmos-chem-phys.net/12/5447/2012/ ER - TY - JOUR T1 - Estimating global and North American methane emissions with high spatial resolution using GOSAT satellite data A1 - Turner, A. J. A1 - Jacob, D. J. A1 - Wecht, K. J. A1 - Maasakkers, J. D. A1 - Lundgren, E. A1 - Andrews, A. E. A1 - Biraud, S. C. A1 - Boesch, H. A1 - Bowman, K. W. A1 - Deutscher, N. M. A1 - Dubey, M. K. A1 - Griffith, D. W. T. A1 - Hase, F. A1 - Kuze, A. A1 - Notholt, J. A1 - Ohyama, H. A1 - Parker, R. A1 - Payne, V. H. A1 - Sussmann, R. A1 - Sweeney, C. A1 - Velazco, V. A. A1 - Warneke, T. A1 - Wennberg, P. O. A1 - Wunch, D. Y1 - 2015/06// JF - Atmospheric Chemistry and Physics VL - 15 IS - 12 SP - 7049 EP - 7069 DO - 10.5194/acp-15-7049-2015 UR - http://www.atmos-chem-phys.net/15/7049/2015/ N2 - We use 2009–2011 space-borne methane observations from the Greenhouse Gases Observing SATellite (GOSAT) to estimate global and North American methane emissions with 4° × 5° and up to 50 km × 50 km spatial resolution, respectively. GEOS-Chem and GOSAT data are first evaluated with atmospheric methane observations from surface and tower networks (NOAA/ESRL, TCCON) and aircraft (NOAA/ESRL, HIPPO), using the GEOS-Chem chemical transport model as a platform to facilitate comparison of GOSAT with in situ data. This identifies a high-latitude bias between the GOSAT data and GEOS-Chem that we correct via quadratic regression. Our global adjoint-based inversion yields a total methane source of 539 Tg a−1 with some important regional corrections to the EDGARv4.2 inventory used as a prior. Results serve as dynamic boundary conditions for an analytical inversion of North American methane emissions using radial basis functions to achieve high resolution of large sources and provide error characterization. We infer a US anthropogenic methane source of 40.2–42.7 Tg a−1, as compared to 24.9–27.0 Tg a−1 in the EDGAR and EPA bottom-up inventories, and 30.0–44.5 Tg a−1 in recent inverse studies. Our estimate is supported by independent surface and aircraft data and by previous inverse studies for California. We find that the emissions are highest in the southern–central US, the Central Valley of California, and Florida wetlands; large isolated point sources such as the US Four Corners also contribute. Using prior information on source locations, we attribute 29–44 % of US anthropogenic methane emissions to livestock, 22–31 % to oil/gas, 20 % to landfills/wastewater, and 11–15 % to coal. Wetlands contribute an additional 9.0–10.1 Tg a−1. ER - TY - JOUR T1 - The role of photo- and thermal degradation for CO2 and CO fluxes in an arid ecosystem A1 - van Asperen, H. A1 - Warneke, T. A1 - Sabbatini, S. A1 - Nicolini, G. A1 - Papale, D. A1 - Notholt, J. Y1 - 2015/07// JF - Biogeosciences VL - 12 IS - 13 SP - 4161 EP - 4174 DO - 10.5194/bg-12-4161-2015 UR - http://www.biogeosciences.net/12/4161/2015/ N2 - Recent studies have suggested the potential importance of abiotic degradation in arid ecosystems. In this study, the role of photo- and thermal degradation in ecosystem CO2 and CO exchange is assessed. A field experiment was performed in Italy using an FTIR-spectrometer (Fourier Transform Infrared) coupled to a flux gradient system and to flux chambers. In a laboratory experiment, field samples were exposed to different temperatures and radiation intensities. No photodegradation-induced CO2 and CO fluxes of in literature suggested magnitudes were found in the field nor in the laboratory study. In the laboratory, we measured CO2 and CO fluxes that were derived from thermal degradation. In the field experiment, CO uptake and emission have been measured and are proposed to be a result of biological uptake and abiotic thermal degradation-production. We suggest that previous studies, addressing direct photodegradation, have overestimated the role of photodegradation and observed fluxes might be due to thermal degradation, which is an indirect effect of radiation. The potential importance of abiotic decomposition in the form of thermal degradation, especially for arid regions, should be considered in future studies. ER - TY - JOUR T1 - Inferring 222Radon soil fluxes from ambient 222Radon activity and eddy covariance measurements of CO2 A1 - van der Laan, S A1 - Manohar, S N A1 - Vermeulen, A T A1 - Bosveld, F C A1 - Meijer, H A J A1 - Manning, A C A1 - van der Molen, M K A1 - van der Laan-Luijkx, I T Y1 - 2016/05// PB - Copernicus Publications JF - Atmospheric Measurement Techniques Discussions VL - 2016 SP - 1 EP - 18 DO - 10.5194/amt-2016-93 UR - http://www.atmos-meas-tech-discuss.net/amt-2016-93/ UR - http://www.atmos-meas-tech-discuss.net/amt-2016-93/amt-2016-93.pdf N2 - We present a new methodology, which we call Single Pair of Observations Technique with Eddy Covariance (SPOT- EC), to estimate regional scale surface fluxes of 222Radon (222Rn) from tower-based observations of 222Rn activity, CO2 mole fractions and direct CO2 flux measurements from eddy covariance. For specific events, the regional (222Rn) surface flux is calculated from short term changes in ambient (222Rn) activity scaled with the ratio of the mean CO2 surface flux for the specific event versus the change in its observed mole fraction. The resulting 222Rn surface emissions are integrated in time (between the moment of observation and the last prior background levels) and space (i.e. over the footprint of the observations). The measurement uncertainty obtained is about ± 15 % for diurnal events and about ± 10 % for longer term (e.g. seasonal or annual) means. The method does not provide continuous observations, but reliable daily averages can be obtained. We applied our method to in-situ observations from two sites in the Netherlands: Cabauw station (CBW) and Lutjewad station (LUT). For LUT, which is an intensive agricultural site, we estimated a mean 222Rn surface flux of (0.29 ± 0.02) atoms cm−2 s−1 with values > 0.5 atoms cm−2 s−1 to the south and southeast. For CBW we estimated a mean 222Rn surface flux of (0.63 ± 0.04) atoms cm−2 s−1. Highest values were observed to the southwest, where the soil type is mainly peat or river-clay respectively. For both stations a good agreement was found between our results and those from measurements with accumulation chambers and two recently published 222Rn soil flux maps for Europe. At both sites, large spatial and temporal variability of 222Rn surface fluxes were observed which would be impractical to measure with an accumulation chamber. SPOT-EC therefore offers an important new tool for estimating region scale 222Rn surface fluxes and for gaining new insights in the driving mechanisms behind 222Rn surface emissions. Practical applications furthermore include calibration of process-based 222Rn soil flux models, validation of atmospheric transport models and performing regional scale inversions of e.g. greenhouse gases via the SPOT 222Rn-tracer method. ER - TY - JOUR T1 - Estimation of continuous anthropogenic CO2: model-based evaluation of CO2, CO, δ13C(CO2) and Δ14C(CO2) tracer methods A1 - Vardag, S. N. A1 - Gerbig, C. A1 - Janssens-Maenhout, G. A1 - Levin, I. Y1 - 2015/11// JF - Atmospheric Chemistry and Physics VL - 15 IS - 22 SP - 12705 EP - 12729 DO - 10.5194/acp-15-12705-2015 UR - http://www.atmos-chem-phys.net/15/12705/2015/ N2 - We investigate different methods for estimating anthropogenic CO2 using modeled continuous atmospheric concentrations of CO2 alone, as well as CO2 in combination with the surrogate tracers CO, δ13C(CO2) and Δ14C(CO2). These methods are applied at three hypothetical stations representing rural, urban and polluted conditions. We find that, independent of the tracer used, an observation-based estimate of continuous anthropogenic CO2 is not yet feasible at rural measurement sites due to the low signal-to-noise ratio of anthropogenic CO2 estimates at such settings. The tracers δ13C(CO2) and CO provide an accurate possibility to determine anthropogenic CO2 continuously, only if all CO2 sources in the catchment area are well characterized or calibrated with respect to their isotopic signature and CO to anthropogenic CO2 ratio. We test different calibration strategies for the mean isotopic signature and CO to CO2 ratio using precise Δ14C(CO2) measurements on monthly integrated as well as on grab samples. For δ13C(CO2), a calibration with annually averaged 14C(CO2) grab samples is most promising, since integrated sampling introduces large biases into anthropogenic CO2 estimates. For CO, these biases are smaller. The precision of continuous anthropogenic CO2 determination using δ13C(CO2) depends on measurement precision of δ13C(CO2) and CO2, while the CO method is mainly limited by the variation in natural CO sources and sinks. At present, continuous anthropogenic CO2 could be determined using the tracers δ13C(CO2) and/or CO with a precision of about 30 %, a mean bias of about 10 % and without significant diurnal discrepancies. Hypothetical future measurements of continuous Δ14C(CO2) with a precision of 5 ‰ are promising for anthropogenic CO2 determination (precision ca. 10–20 %) but are not yet available. The investigated tracer-based approaches open the door to improving, validating and reducing biases of highly resolved emission inventories using atmospheric observation and regional modeling. ER - TY - JOUR T1 - Comparisons of continuous atmospheric CH4, CO2 and N2O measurements – results from a travelling instrument campaign at Mace Head A1 - Vardag, S. N. A1 - Hammer, S. A1 - O'Doherty, S. A1 - Spain, T. G. A1 - Wastine, B. A1 - Jordan, A. A1 - Levin, I. Y1 - 2014/08// JF - Atmospheric Chemistry and Physics VL - 14 IS - 16 SP - 8403 EP - 8418 DO - 10.5194/acp-14-8403-2014 UR - http://www.atmos-chem-phys.net/14/8403/2014/ N2 - A 2-month measurement campaign with a Fourier transform infrared analyser as a travelling comparison instrument (TCI) was performed at the Advanced Global Atmospheric Gases Experiment (AGAGE) and World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) station at Mace Head, Ireland. The aim was to evaluate the compatibility of atmospheric methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) measurements of the routine station instrumentation, consisting of a gas chromatograph (GC) for CH4 and N2O as well as a cavity ring-down spectroscopy (CRDS) system for CH4 and CO2. The advantage of a TCI approach for quality control is that the comparison covers the entire ambient air measurement system, including the sample intake system and the data evaluation process. For initial quality and performance control, the TCI was run in parallel with the Heidelberg GC before and after the measurement campaign at Mace Head. Median differences between the Heidelberg GC and the TCI were well within the WMO inter-laboratory compatibility target for all three greenhouse gases. At Mace Head, the median difference between the station GC and the TCI were −0.04 nmol mol−1 for CH4 and −0.37 nmol mol−1 for N2O (GC-TCI). For N2O, a similar difference (−0.40 nmol mol−1) was found when measuring surveillance or working gas cylinders with both instruments. This suggests that the difference observed in ambient air originates from a calibration offset that could partly be due to a difference between the WMO N2O X2006a reference scale used for the TCI and the Scripps Institution of Oceanography (SIO-1998) scale used at Mace Head and in the whole AGAGE network. Median differences between the CRDS G1301 and the TCI at Mace Head were 0.12 nmol mol−1 for CH4 and 0.14 μmol mol−1 for CO2 (CRDS G1301 – TCI). The difference between both instruments for CO2 could not be explained, as direct measurements of calibration gases show no such difference. The CH4 differences between the TCI, the GC and the CRDS G1301 at Mace Head are much smaller than the WMO inter-laboratory compatibility target, while this is not the case for CO2 and N2O. ER - TY - JOUR T1 - First continuous measurements of δ18O-CO2 in air with a Fourier transform infrared spectrometer A1 - Vardag, S. N. A1 - Hammer, S. A1 - Sabasch, M. A1 - Griffith, D. W. T. A1 - Levin, I. Y1 - 2015/02// JF - Atmospheric Measurement Techniques VL - 8 IS - 2 SP - 579 EP - 592 DO - 10.5194/amt-8-579-2015 UR - http://www.atmos-meas-tech.net/8/579/2015/ N2 - The continuous in situ measurement of δ18O in atmospheric CO2 opens a new door to differentiating between CO2 source and sink components with high temporal resolution. Continuous 13C–CO2 measurement systems have already been commercially available for some time, but until now, only few instruments have been able to provide a continuous measurement of the oxygen isotope ratio in CO2. Besides precise 13C/12C observations, the Fourier transform infrared (FTIR) spectrometer is also able to measure the 18O / 16O ratio in CO2, but the precision and accuracy of the measurements have not yet been evaluated. Here we present a first analysis of δ18O-CO2 (and δ13C-CO2) measurements with the FTIR analyser in Heidelberg. We used Allan deviation to determine the repeatability of δ18O-CO2 measurements and found that it decreases from 0.25‰ for 10 min averages to about 0.1‰ after 2 h and remains at that value up to 24 h. We evaluated the measurement precision over a 10-month period (intermediate measurement precision) using daily working gas measurements and found that our spectrometer measured δ18O-CO2 to better than 0.3‰ at a temporal resolution of less than 10 min. The compatibility of our FTIR-spectrometric measurements to isotope-ratio mass-spectrometric (IRMS) measurements was determined by comparing FTIR measurements of cylinder gases and ambient air with IRMS measurements of flask samples, filled with gases of the same cylinders or collected from the same ambient air intake. Two-sample t tests revealed that, at the 0.01 significance level, the FTIR and the IRMS measurements do not differ significantly from each other and are thus compatible. We describe two weekly episodes of ambient air measurements, one in winter and one in summer, and discuss what potential insights and new challenges combined highly resolved CO2, δ13C-CO2 and δ18O-CO2 records may provide in terms of better understanding regional scale continental carbon exchange processes. ER - TY - JOUR T1 - Analysis of the vertical radon structure at the Spanish “El Arenosillo” tower station A1 - Vargas, A. A1 - Arnold, D. A1 - Adame, J.A. A1 - Grossi, C. A1 - Hernández-Ceballos, M.A. A1 - Bolivar, J.P. Y1 - 2015/01// JF - Journal of Environmental Radioactivity VL - 139 SP - 1 EP - 17 DO - 10.1016/j.jenvrad.2014.09.018 UR - http://linkinghub.elsevier.com/retrieve/pii/S0265931X14002847 ER - TY - JOUR T1 - First Observations of the Fourth Generation Synthetic Halocarbons HFC-1234yf, HFC-1234ze(E), and HCFC-1233zd(E) in the Atmosphere A1 - Vollmer, Martin K. A1 - Reimann, Stefan A1 - Hill, Matthias A1 - Brunner, Dominik Y1 - 2015/03// JF - Environmental Science & Technology VL - 49 IS - 5 SP - 2703 EP - 2708 DO - 10.1021/es505123x UR - http://pubs.acs.org/doi/abs/10.1021/es505123x ER - TY - JOUR T1 - Modern inhalation anesthetics: Potent greenhouse gases in the global atmosphere A1 - Vollmer, Martin K. A1 - Rhee, Tae Siek A1 - Rigby, Matt A1 - Hofstetter, Doris A1 - Hill, Matthias A1 - Schoenenberger, Fabian A1 - Reimann, Stefan Y1 - 2015/03// JF - Geophysical Research Letters VL - 42 IS - 5 SP - 1606 EP - 1611 DO - 10.1002/2014GL062785 UR - http://doi.wiley.com/10.1002/2014GL062785 ER - TY - JOUR T1 - Abrupt reversal in emissions and atmospheric abundance of HCFC-133a (CF 3 CH 2 Cl) A1 - Vollmer, Martin K. A1 - Rigby, Matt A1 - Laube, Johannes C. A1 - Henne, Stephan A1 - Rhee, Tae Siek A1 - Gooch, Lauren J. A1 - Wenger, Angelina A1 - Young, Dickon A1 - Steele, L. Paul A1 - Langenfelds, Ray L. A1 - Brenninkmeijer, Carl A. M. A1 - Wang, Jia-Lin A1 - Ou-Yang, Chang-Feng A1 - Wyss, Simon A. A1 - Hill, Matthias A1 - Oram, David E. A1 - Krummel, Paul B. A1 - Schoenenberger, Fabian A1 - Zellweger, Christoph A1 - Fraser, Paul J. A1 - Sturges, William T. A1 - O'Doherty, Simon A1 - Reimann, Stefan Y1 - 2015/10// JF - Geophysical Research Letters VL - 42 IS - 20 SP - 8702 EP - 8710 DO - 10.1002/2015GL065846 UR - http://doi.wiley.com/10.1002/2015GL065846 ER - TY - JOUR T1 - Isotopic evidence for biogenic molecular hydrogen production in the Atlantic Ocean A1 - Walter, S. A1 - Kock, A. A1 - Steinhoff, T. A1 - Fiedler, B. A1 - Fietzek, P. A1 - Kaiser, J. A1 - Krol, M. A1 - Popa, M. E. A1 - Chen, Q. A1 - Tanhua, T. A1 - Röckmann, T. Y1 - 2016/01// JF - Biogeosciences VL - 13 IS - 1 SP - 323 EP - 340 DO - 10.5194/bg-13-323-2016 UR - http://www.biogeosciences.net/13/323/2016/ N2 - Oceans are a net source of molecular hydrogen (H2) to the atmosphere. The production of marine H2 is assumed to be mainly biological by N2 fixation, but photochemical pathways are also discussed. We present measurements of mole fraction and isotopic composition of dissolved and atmospheric H2 from the southern and northern Atlantic between 2008 and 2010. In total almost 400 samples were taken during 5 cruises along a transect between Punta Arenas (Chile) and Bremerhaven (Germany), as well as at the coast of Mauritania. The isotopic source signatures of dissolved H2 extracted from surface water are highly deuterium-depleted and correlate negatively with temperature, showing δD values of (−629 ± 54) ‰ for water temperatures at (27 ± 3) °C and (−249 ± 88) ‰ below (19 ± 1) °C. The results for warmer water masses are consistent with the biological production of H2. This is the first time that marine H2 excess has been directly attributed to biological production by isotope measurements. However, the isotope values obtained in the colder water masses indicate that beside possible biological production, a significant different source should be considered. The atmospheric measurements show distinct differences between both hemispheres as well as between seasons. Results from the global chemistry transport model TM5 reproduce the measured H2 mole fractions and isotopic composition well. The climatological global oceanic emissions from the GEMS database are in line with our data and previously published flux calculations. The good agreement between measurements and model results demonstrates that both the magnitude and the isotopic signature of the main components of the marine H2 cycle are in general adequately represented in current atmospheric models despite a proposed source different from biological production or a substantial underestimation of nitrogen fixation by several authors. ER - TY - JOUR T1 - Comparison between static chamber and tunable diode laser-based eddy covariance techniques for measuring nitrous oxide fluxes from a cotton field A1 - Wang, Kai A1 - Zheng, Xunhua A1 - Pihlatie, Mari A1 - Vesala, Timo A1 - Liu, Chunyan A1 - Haapanala, Sami A1 - Mammarella, Ivan A1 - Rannik, Üllar A1 - Liu, Huizhi Y1 - 2013/04// JF - Agricultural and Forest Meteorology VL - 171-172 SP - 9 EP - 19 DO - 10.1016/j.agrformet.2012.11.009 UR - http://linkinghub.elsevier.com/retrieve/pii/S0168192312003462 ER - TY - JOUR T1 - Retrieval of tropospheric column-averaged CH4 mole fraction by solar absorption FTIR-spectrometry using N2O as a proxy A1 - Wang, Z. A1 - Deutscher, N. M. A1 - Warneke, T. A1 - Notholt, J. A1 - Dils, B. A1 - Griffith, D. W. T. A1 - Schmidt, M. A1 - Ramonet, M. A1 - Gerbig, C. Y1 - 2014/10// JF - Atmospheric Measurement Techniques VL - 7 IS - 10 SP - 3295 EP - 3305 DO - 10.5194/amt-7-3295-2014 UR - http://www.atmos-meas-tech.net/7/3295/2014/ N2 - Tropospheric column-averaged CH4 mole fractions were derived from ground-based column absorption measurements. The method uses stratospheric N2O columns to correct for the stratospheric contribution to the CH4 total column. The method was applied to four Total Carbon Column Observing Network (TCCON) sites covering locations from the Northern Arctic to the tropics. It performs well for all sites. The derived tropospheric CH4 concentrations were compared with profiles measured by aircraft at three sites. The results indicate an inter-site consistency within 6 ppb (~0.3%). With aircraft profiles up to 3 km, the seasonal behavior of the derived tropospheric CH4 concentration was also checked, revealing a difference of around 20 ppb. The mean relative uncertainty of the four sites, as estimated from the daily standard deviations, is 0.23%. ER - TY - JOUR T1 - Retrieval of methane source strengths in Europe using a simple modeling approach to assess the potential of spaceborne lidar observations A1 - Weaver, C. A1 - Kiemle, C. A1 - Kawa, S. R. A1 - Aalto, T. A1 - Necki, J. A1 - Steinbacher, M. A1 - Arduini, J. A1 - Apadula, F. A1 - Berkhout, H. A1 - Hatakka, J. Y1 - 2014/03// JF - Atmospheric Chemistry and Physics VL - 14 IS - 5 SP - 2625 EP - 2637 DO - 10.5194/acp-14-2625-2014 UR - http://www.atmos-chem-phys.net/14/2625/2014/ N2 -

We investigate the sensitivity of future spaceborne lidar measurements to changes in surface methane emissions. We use surface methane observations from nine European ground stations and a Lagrangian transport model to infer surface methane emissions for 2010. Our inversion shows the strongest emissions from the Netherlands, the coal mines in Upper Silesia, Poland, and wetlands in southern Finland. The simulated methane surface concentrations capture at least half of the daily variability in the observations, suggesting that the transport model is correctly simulating the regional transport pathways over Europe. With this tool we can test whether proposed methane lidar instruments will be sensitive to changes in surface emissions. We show that future lidar instruments should be able to detect a 50% reduction in methane emissions from the Netherlands and Germany, at least during summer.

ER - TY - JOUR T1 - Spatially resolving methane emissions in California: constraints from the CalNex aircraft campaign and from present (GOSAT, TES) and future (TROPOMI, geostationary) satellite observations A1 - Wecht, K. J. A1 - Jacob, D. J. A1 - Sulprizio, M. P. A1 - Santoni, G. W. A1 - Wofsy, S. C. A1 - Parker, R. A1 - Bösch, H. A1 - Worden, J. Y1 - 2014/08// JF - Atmospheric Chemistry and Physics VL - 14 IS - 15 SP - 8173 EP - 8184 DO - 10.5194/acp-14-8173-2014 UR - http://www.atmos-chem-phys.net/14/8173/2014/ N2 - We apply a continental-scale inverse modeling system for North America based on the GEOS-Chem model to optimize California methane emissions at 1/2° × 2/3° horizontal resolution using atmospheric observations from the CalNex aircraft campaign (May–June 2010) and from satellites. Inversion of the CalNex data yields a best estimate for total California methane emissions of 2.86 ± 0.21 Tg a−1, compared with 1.92 Tg a−1 in the EDGAR v4.2 emission inventory used as a priori and 1.51 Tg a−1 in the California Air Resources Board (CARB) inventory used for state regulations of greenhouse gas emissions. These results are consistent with a previous Lagrangian inversion of the CalNex data. Our inversion provides 12 independent pieces of information to constrain the geographical distribution of emissions within California. Attribution to individual source types indicates dominant contributions to emissions from landfills/wastewater (1.1 Tg a−1), livestock (0.87 Tg a−1), and gas/oil (0.64 Tg a−1). EDGAR v4.2 underestimates emissions from livestock, while CARB underestimates emissions from landfills/wastewater and gas/oil. Current satellite observations from GOSAT can constrain methane emissions in the Los Angeles Basin but are too sparse to constrain emissions quantitatively elsewhere in California (they can still be qualitatively useful to diagnose inventory biases). Los Angeles Basin emissions derived from CalNex and GOSAT inversions are 0.42 ± 0.08 and 0.31 ± 0.08 Tg a−1 that the future TROPOMI satellite instrument (2015 launch) will be able to constrain California methane emissions at a detail comparable to the CalNex aircraft campaign. Geostationary satellite observations offer even greater potential for constraining methane emissions in the future. ER - TY - JOUR T1 - Improvement of the retrieval algorithm for GOSAT SWIR XCO2 and XCH4 and their validation using TCCON data A1 - Yoshida, Y. A1 - Kikuchi, N. A1 - Morino, I. A1 - Uchino, O. A1 - Oshchepkov, S. A1 - Bril, A. A1 - Saeki, T. A1 - Schutgens, N. A1 - Toon, G. C. A1 - Wunch, D. A1 - Roehl, C. M. A1 - Wennberg, P. O. A1 - Griffith, D. W. T. A1 - Deutscher, N. M. A1 - Warneke, T. A1 - Notholt, J. A1 - Robinson, J. A1 - Sherlock, V. A1 - Connor, B. A1 - Rettinger, M. A1 - Sussmann, R. A1 - Ahonen, P. A1 - Heikkinen, P. A1 - Kyrö, E. A1 - Mendonca, J. A1 - Strong, K. A1 - Hase, F. A1 - Dohe, S. A1 - Yokota, T. Y1 - 2013/06// JF - Atmospheric Measurement Techniques VL - 6 IS - 6 SP - 1533 EP - 1547 DO - 10.5194/amt-6-1533-2013 UR - http://www.atmos-meas-tech.net/6/1533/2013/ ER - TY - JOUR T1 - Plume mapping and isotopic characterisation of anthropogenic methane sources A1 - Zazzeri, G. A1 - Lowry, D. A1 - Fisher, R.E. A1 - France, J.L. A1 - Lanoisellé, M. A1 - Nisbet, E.G. Y1 - 2015/06// JF - Atmospheric Environment VL - 110 SP - 151 EP - 162 DO - 10.1016/j.atmosenv.2015.03.029 UR - http://linkinghub.elsevier.com/retrieve/pii/S1352231015002538 ER -