Synergetic use of IASI profile and TROPOMI total-column level 2 methane retrieval products
The thermal infrared nadir spectra of IASI (Infrared Atmospheric Sounding Interferometer) are successfully used for retrievals of different atmospheric trace gas profiles. However, these retrievals offer generally reduced information about the lowermost tropospheric layer due to the lack of thermal contrast close to the surface. Spectra of scattered solar radiation observed in the near-infrared and/or shortwave infrared, for instance by TROPOMI (TROPOspheric Monitoring Instrument), offer higher sensitivity near the ground and are used for the retrieval of total-column-averaged mixing ratios of a variety of atmospheric trace gases.
For this product the different sensitivities of the IASI and TROPOMI satellite sensors are explored, leading to a global CH4 dataset that is representative for the troposphere from ground to about 450hPa; a description of the synergetic combination method is given in Schneider et al., 2022.