On the joint use of IASI and GOSAT retrievals in the thermal infrared
Résumé
GOSAT (Greenhouse Gases Observing SATellite) is a satellite dedicated to the study of greenhouses gases. It carries an infrared Fourier transform spectrometer (Thermal And Near infrared Sensor for carbon Observation-Fourier Transform Spectrometer or TANSO-FTS), which acquires spectra in 4 bands, located in the Near-Infrared (NIR), ShortWave Infrared (SWIR) and Thermal Infrared (TIR). An imager (Cloud and Aerosol Imager or TANSO-CAI) enables to gain information on clouds and aerosols, and this information is used to improve the quality of CO2 and CH4 retrievals. IASI (Infrared Atmospheric Sounding Interferometer) designed by CNES for Eumetsat is carried by the MetOp-A satellite. It is used for operational meteorology and is also interesting for greenhouse gases as well as for atmospheric chemistry and climate. We looked for close spatial and temporal coincidences with six TCCON sites where high resolution FTIR measurements are performed routinely. Cloud-free and spatially homogeneous fields of view (IFOVs) were selected using CAI images. The TCCON retrieved VMR profiles have been used as reference and compared with those we retrieved from coincident measurements of GOSAT and IASI. We used the [1240;1320] cm-1 window for CH4, and the [980;1100] cm-1 window for O3 retrieval. Finally, we will highlight the potential to further improve the results using the synergy between measurements in the TIR and the SWIR spectral domains.