The scientific evidence of global warming demands monitoring of the global distribution of greenhouse gases for understanding the underlying processes, for climate prediction and the development of mitigation strategies. These challenges require accurate knowledge of the present-day global distribution of the most important greenhouse gases CO2 and CH4 including their temporal variation. In recent times, several spaceborne missions were launched to determine the atmospheric abundance of these trace gases.
For example, in the year 2002, ESA launched the SCIAMACHY instrument aboard the ENVISAT satellite, which was fully operational until 2012. This exploring mission demonstrated convincingly the capability to determine the amount of atmospheric greenhouse gas (in particular CH4) from space. Later, in 2009 the dedicated greenhouse gas mission GOSAT was successfully launched by the Japanese space agency JAXA, followed up by NASA’s OCO-2 in 2014. The interpretation of the mission data not only requires radiometric accurate measurements but also dedicated approaches to achieve the required data accuracy for the well-mixed trace gases CO2 and CH4.
At the Earth science group within SRON, we focus on scientific data interpretation of these missions to demonstrate their scientific value and to advance our current knowledge on the distribution of sources and sinks of greenhouse gases. By means of our dedicated retrieval algorithms the total column mixing ratio of CH4 and CO2 can be inferred from the radiometric measurements, which are regularly validated with on-ground reference measurements. Long-term greenhouse gas data records are developed by SRON as part of the Climate Change Initiative (CCI) of ESA and the Copernicus Climate Change Service (C3S) of ECMWF. SRON also performs the operational processing of GOSAT XCH4 within the Copernicus Atmosphere Monitoring Service (CAMS) project of ECMWF.
Based on our successful retrieval algorithms and data processing software for the current greenhouse gas mission, SRON develops software for the operational processing of CH4 for Sentinel 5 on the METOP-SG satellite and its precursor mission Sentinel-5P/TROPOMI. Moreover, using this algorithm heritage, SRON advices the European Space Agency via dedicated assessment studies on the design and implementation of the future carbon dioxide monitoring mission Sentinel-7.