ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-5-1589-2005 Solar occultation with SCIAMACHY: algorithm description and first validation Meyer J. 1 Bracher A. 1 Rozanov A. 1 Schlesier A. C. 1 Bovensmann H. 1 Burrows J. P. 1 Institute of Environmental Physics, University of Bremen, Germany 22 06 2005 5 6 1589 1604 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/5/1589/2005/acp-5-1589-2005.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/5/1589/2005/acp-5-1589-2005.pdf

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 of simulating 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 O<sub>3</sub> and NO<sub>2</sub> vertical profile retrievals have been validated with data from ozone sondes and satellite based occultation instruments. The validation shows very promising results for SCIAMACHY O<sub>3</sub> and NO<sub>2</sub> values between 15 to 35km with errors of the order of 10% and 15%, respectively.