During the last years the DOAS retrieval method has been successfully applied to GOME/ERS-2 satellite data (UV-visible spectra of reflected sunlight) to retrieve total column amounts of, e.g., atmospheric ozone, NO2 and BrO. Due to the much stronger dependence of the absorption cross-section of "line-absorbers" such as H2O, CO2, CO, CH4, N2O, and O2, on wavelength, pressure and temperature, the standard DOAS method cannot directly be applied to these gases absorbing in the visible (VIS) and near-infrared (NIR) spectral region observed by SCIAMACHY/ENVISAT.
In order to retrieve the total columns of these important gases from SCIAMACHY VIS/NIR nadir measurements, the Weighting-Function-Modified (WFM) DOAS method has been proposed recently (Buchwitz et al, JGR 2000). The method and its current implementation will be described and first results concerning its application to the retrieval of water vapor total column amounts from GOME VIS nadir measurements will be presented.
