Absolute Calibration and Degradation of Sciamachy/gome Reflectances

The goal of this study is to develop a method to quantify SCIAMACHY degradation and calibration in the UV, where the focus is on the O3 profile wavelength range 270-330 nm. Awaiting SCIAMACHY data reprocessing, the method has been performed on GOME observations, SCIAMACHY predecessor. The approach followed is to compare GOME reflectivity spectra with simulated spectra using collocated independent measurements of O3, temperature and pressure. For this a vector radiative transfer model (RTM) was used to avoid errors introduced by the GOME polarisation correction algorithm, (degradation of) the GOME polarisation measurements and errors in the forward radiances introduced when using a scalar RTM.