ENVISAT/SCIAMACHY First Results on Instrument Performance, Retrieval and Validation of CO, CH4 and Other Greenhouse Gases

The Scanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY (SCIAMACHY), launched on board the ENVISAT satellite on 1 March 2002, currently captures the absorption signatures in earth-scattered solar light due to some sixteen chemical species, as well as clouds and aerosols in a variety of nadir, limb, solar occultation, and lunar occultation modes, in eight ultraviolet, visible and near infrared channels (covering 240 nm to 2380 nm). Channels 6, 7 and 8, which work in the near infrared, were developed, calibrated and characterized in-flight at SRON. Of considerable interest is channel 8 in nadir mode, which may be used for the detection of tropospheric H₂O, N₂O, and in particular, CO and CH₄. These are important atmospheric constituents for understanding climate change and the knowledge of their global distribution will be considerably enhanced using satellite measurements. The final results of a channel 8 in-flight performance assessment will be presented along with retrieval and validation results and a retrieval method sensitivity and robustness analysis. Our retrieval results are derived independently of the operational ENVISAT/SCIAMACHY Level 2 data product and thus provide an additional point of comparison for validation, verification and, ultimately, incorporation into global circulation models.