Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 9 3 2009 10.5194/acpd-9-12615-2009 http://www.atmos-chem-phys-discuss.net/9/12615/2009/ http://www.atmos-chem-phys-discuss.net/9/12615/2009/acpd-9-12615-2009.html http://www.atmos-chem-phys-discuss.net/9/12615/2009/acpd-9-12615-2009.pdf 12615 12643 2009-05-29 Influence of scintillation on GOMOS ozone retrievals V. F. Sofieva viktoria.sofieva@fmi.fi V. Kan F. Dalaudier E. Kyrölä J. Tamminen J.-L. Bertaux A. Hauchecorne D. Fussen F. Vanhellemont Earth observation, Finnish Meteorological Institute, Helsinki, Finland Organization of Russian Academy of Sciences A.M. Obukhov Institute of Atmospheric Physics RAS, Russia LATMOS, Verrières-le-Buisson Cedex, France Institut d'Aeronomie Spatiale de Belgique, Brussels, Belgium The stellar light passed through the Earth atmosphere is affected by refractive effects, which should be taken into account in retrievals from stellar occultation measurements. Scintillation caused by air density irregularities is a nuisance for retrievals of atmospheric composition. In this paper, we consider the influence of scintillation on stellar occultation measurements and on quality of ozone retrievals from these measurements, based on experience of the GOMOS (Global Ozone Monitoring by Occultation of Stars) instrument on board the Envisat satellite. <br><br> In the GOMOS retrievals, the scintillation effect is corrected using scintillation measurements by the fast photometer. We present quantitative estimates of the current scintillation correction quality and of the impact of scintillation on ozone retrievals by GOMOS. The analysis has shown that the present scintillation correction efficiently removes the distortion of transmission spectra caused by anisotropic scintillations. The impact of errors of dilution and anisotropic scintillation correction on quality of ozone retrievals is negligible. However, the current scintillation correction is not able to remove the wavelength-dependent distortion of transmission spectra caused by isotropic scintillations, which can be present in off-orbital-plane occultations. This distortion may result in error of ozone retrievals of 0.5–1.5% at altitudes 20–40 km. This contribution to the error budget is significant for bright stars. The advanced inversion methods that can minimize the influence of scintillation correction error are also discussed. Dalaudier F., Kan, V., and Gurvich, A. S.: Chromatic refraction with global ozone monitoring by occultation of stars. I. Description and scintillation correction, Appl. Optics, 40, 866–877, 2001. Dalaudier, F. and Sofieva, V. F.: Simulation of optical scintillations, GOMOS special issue, in preparation, 2009. GOMOS ESL, Algorithm Theoretical Basis Document, version 2.0, 2006 Gurvich, A. 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