Carbon Monoxide and Methane Retrievals from Short Wave Infrared Nadir Observations of SCIAMACHY and GOSAT
Schreier, Franz; Gimeno Garcia, Sebastian; Lichtenberg, GŁnter; Hess, Michael
DLR - Remote Sensing Technology Institute, GERMANY
Nadir observations in the short wave infrared channels of SCIAMACHY and GOSAT reveal information on the atmospheric carbon gases methane, carbon monoxide (SCIAMACHY only) and carbon dioxide. For the estimation of vertical column densities from SCIAMACHY measurements the Beer InfraRed Retrieval Algorithm (BIRRA) code has been developed that performs a nonlinear or separable least squares fit of concentration profile scaling factors along with some auxiliary parameters. Our current work focuses on improvements with respect to wavelength calibration, a more flexible multi-spectral window fitting scheme, and a better modeling of SCIAMACHY's channel 8 spectral response function. Furthermore the impact of a better climatology for pressure, temperature, and water vapor is investigated. Despite the different measurement principle (Fourier transform instead of grating spectrometer) the methodology of vertical column density retrieval from GOSAT is largely identical to SCIAMACHY, and accordingly BIRRA can be used without significant changes. Our contribution will briefly describe these code extensions and presents examples from carbon monoxide (SCIAMACHY channel 8) and methane (SCIAMACHY channel 6 and GOSAT band 2) retrievals.