Highlights of GOMOS stellar occultation measurements and recent improvements of the data

International audienceEuropean Space Agency’s GOMOS (Global Ozone Monitoring by Occultation of Stars) instrument on-board Envisat satellite operated during 2002 - 2012. During the ten years of the mission, GOMOS instrument successfully measured vertical profiles of O3, NO2, NO3 and aerosols, including polar mesospheric clouds and polar stratospheric clouds, using UV-VIS channel and O2 and H2O using two near--IR channels. The best quality of data was obtained during the night time, but recently also the data processing of the day time observations have been improved. The two photometers of GOMOS have been used to retrieve high vertical resolution temperature profiles as well as for studying turbulence and gravity waves. Constituents with weak spectral signatures, such as OClO and Na, can be detected using temporal averaging. GOMOS measurements provide global coverage with about 200-400 daily profile measurements. Vertically the measurements extend from 5 km to 100 km with varying valid altitude range depending on constituent. Stellar occultation technique ensures high vertical resolution of 2-4 km, very accurate altitude registration and relatively simple data retrieval. The self-calibrating feature of the occultation technique is particularly suitable for long term trend analysis and therefore useful for studying climate-chemistry interactions. In particular, the high quality night time observations of ozone, NO2 and NO3 have been used in several time series analysis and studies related to middle atmosphere chemistry and dynamics including effects of the energetic particles. The joint SAGE II and GOMOS ozone profile time series have shown upper stratospheric ozone recovery at most latitudes outside the polar regions.In this presentation we discuss the highlights of GOMOS measurements and introduce the recent improvements on the data quality, including, in particular, day time measurements and ozone profiles in the very interesting upper troposphere - lower stratosphere region