Mapping of the Carbon Dioxide Mid-tropospheric Mixing Ratio and Methane Total Column from Hyperspectral Sounders Data

This paper presents at first an updated status of atmospheric column-average CO2 mixing ratio XCO2 retrieval scheme based on clear-sky or cloud-cleared AIRS/EOS-Aqua data inversion algorithm. Maps of monthly averaged XCO2 estimates have been produced for extensive region of Siberia with spatial averaging about 1.5 x1.5. Similar methodology has been applied for the retrieval of “instant” XCO2 from clear sky IASI data. The retrievals have been produced for July, 7, 2008 and for the region of airborne measurements made in the frame of YAK-AEROSIB campaign. The accuracy of XCO2 retrievals assessed by comparison with aircraft flask CO2 observations is about 2.2 ppmv. With respect to the CH4 column retrieval from IASI data the approach has been developed based upon the application of iterative physical inversion algorithm to clear-sky IASI data. The performance of the retrieval algorithm is evaluated in the case study experiment involving IASI data covering the Siberia region. The feasibility of IASI-based QCH4 retrieval has been evaluated through comparison with collocated and quasi-synchronous AIRS-based QCH4 retrievals. The values of standard deviation between both products (averaged over the grid 2 x2) are less than 3%