Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 5 1 2005 10.5194/acpd-5-17-2005 http://www.atmos-chem-phys-discuss.net/5/17/2005/ http://www.atmos-chem-phys-discuss.net/5/17/2005/acpd-5-17-2005.html http://www.atmos-chem-phys-discuss.net/5/17/2005/acpd-5-17-2005.pdf 17 66 2005-01-10 Solar occultation with SCIAMACHY: algorithm description and first validation J. Meyer A. Bracher A. Rozanov A. C. Schlesier H. Bovensmann J. P. Burrows Institute of Environmental Physics, University of Bremen, Germany This presentation concentrates on solar occultation measurements with the spaceborne spectrometer SCIAMACHY in the UV-Vis wavelength range. Solar occultation measurements provide unique information about the vertical distribution of atmospheric constituents. For retrieval of vertical trace gas concentration profiles, an algorithm has been developed based on the optimal estimation method. The forward model is capable to simulate the extinction signals of different species as they occur in atmospheric transmission spectra obtained from occultation measurements. Furthermore, correction algorithms have been implemented to address shortcomings of the tangent height pre-processing and inhomogeneities of measured solar spectra. First results of O₃ and NO₂ vertical profile retrievals have been validated with data from ozone sondes and satellite based occultation instruments. The validation shows very promising results for SCIAMACHY O₃ and NO₂ values between 15 to 35 km with errors in the order of 10% and 15%, respectively.