Improvements in the tropical ozone profile retrieval from GOME-UV/Vis nadir spectra

Abstract

The Global Ozone Monitoring Experiment (GOME) is a nadir viewing grating spectrometer measuring radiances in the visible and ultraviolet spectral range. The analysis of sun-normalized nadir spectra from GOME enables us to retrieve height resolved ozone distributions. The retrieval is based upon the FURM algorithm (Full Retrieval Method) which uses the advanced optimal estimation scheme. The spectral data require accurate radiometric calibration with regard to the increasing degradation of the instrument with time. In this paper, a calibration and degradation correction will be presented which enables us to extend the spectral range to shorter wavelengths enhancing the stratospheric information content of the retrieved profiles. This helps to avoid non-physical profile structures often observed in the tropics, where the ozone maximum is sensitive to this spectral range. Results in the low latitude range are compared with experimental results from the HALogen Occultation Experiment (HALOE) and retrieval results from former versions of FURM and show generally much better agreement.