The Integrated Carbon Observation System (ICOS) is committed to producing and providing long-term, high-precision, and open in situ data as per the FAIR principles.
ICOS measurements, of concentrations and fluxes of greenhouse gases in the atmosphere, ocean, and on land, are essential information for diverse scientific communities: satellite experts for calibration and validation, modelers to constrain their models and improve predictions of climate trends, or developers to produce new tools based on Earth Observation data. ICOS multi-domain measurements are invaluable as the need for high-quality, in situ calibration/validation data grows in proportion to advances in satellite observations. Other potential collaborations with remote sensing communities can be forged by the experience ICOS has gained in urban environments and addressing climate risks.
ICOS and the European Space Agency (ESA) are exploring opportunities to join forces to combine in situ and satellite measurements for calibration/validation, to ensure the accuracy, reliability and consistency of satellite data. ESA currently funds calibration/validation campaigns, but ICOS data gives ESA the benefit of using near-real-time, long-time series and quality-controlled intercomparable measurements at several locations in Europe and beyond. ICOS is also ready to improve the routine measurements to match satellite requirements – a gap analysis is currently underway in the framework of the EU-project, NUBICOS - New Users for a Better ICOS.
What each ICOS domain can offer the remote sensing community:
Atmosphere
ICOS provides high-precision, ground-based measurements of CO₂, CH₄, N₂O, and CO which are essential calibration and validation inputs for satellite data. Historical ICOS data also provides long-term context for satellite measurements. The use of ICOS data improves atmospheric transport modeling, and aids in attributing emissions to specific sources and sinks.
The synergy between ICOS and upcoming CO2M mission can enhance spatial and temporal resolution, enabling precise monitoring and verification of anthropogenic emissions, thereby supporting Europe’s climate goals
Ecosystem
In the Ecosystem domain, we are collaborating with the satellite community to implement new ICOS measurements that are more interoperable for calibration and validation. Within the NUBICOS project, we pilot the measurement of additional Essential Climate Variables (ECVs) like fAPAR, Leaf Area Index (LAI) and Land Surface Temperature (LST). These variables will support validation of the Sentinel-2 and Sentinel-3 products. In collaboration with cal/val experts, we are defining the best protocols for each measurement in terms of setup, number of sensors and processing.
Ocean
ICOS ocean stations make long-term measurements of Essential Ocean Variables (EOVs) like Surface Carbon Dioxide (CO₂) Partial Pressure (pCO₂), Sea Surface Salinity (SSS), and Sea Surface Temperature (SST). These parameters are vital for quantifying and understanding ocean carbon dynamics, air-sea fluxes, and the global carbon cycle. ICOS ocean data significantly enhance satellite greenhouse gas (GHG) observations by providing in situ measurements for validation, bias correction, and improved accuracy in flux calculations. They help address satellite limitations such as cloud cover, surface-layer distinctions, and spectral sensitivities, refining boundary layer models and climate predictions. The integration of ICOS data with satellite observations enhances data assimilation, fills observational gaps, and improves understanding of the global GHG cycle, thereby contributing to the upcoming CO2M satellite mission and supporting actionable climate policies.