Validation of CO2 Retrievals from GOSAT SWIR TANSO-FTS data, and Evaluation of Advanced spectral SWIR/TIR Synergistic Methodologies for Lowermost Tropospheric CO2 Retrieval.

Abstract : The retrieval of the lowermost tropospheric content of greenhouse gases such as CO2 and CH4 is a critical issue for characterizing their sources and sinks. One key question lies in the methods to extract the best information of the concentration of these gases in the lower troposphere from satellite observations. We present first a validation of our atmospheric CO2 products retrieved from SWIR TANSO-FTS data on board GOSAT. This validation is based on the comparison between our CO2 products with TCCON products and other CO2 products from GOSAT data provided by several research groups (ACOS, NIES, SRON/KIT, and Univ. of Leicester). Then, we present spectral synergy methodologies exploiting SWIR and TIR spectral bands of TANSO-FTS and we discuss their expected added value to improve the retrieval of the lower tropospheric CO2 product. A specific approach combining SWIR and TIR level 2 products is compared with a more classical SWIR/TIR level 1 synergy algorithm and preliminary results are presented using synthetic TIR and SWIR GOSAT measurements.