ACP Atmospheric Chemistry and Physics ACP Atmos. Chem. Phys. 1680-7324 Copernicus Publications Göttingen, Germany 10.5194/acp-10-9505-2010 GOMOS data characterisation and error estimation Tamminen J. 1 Kyrölä E. 1 Sofieva V. F. 1 Laine M. 1 Bertaux J.-L. 2 Hauchecorne A. 2 Dalaudier F. 2 Fussen D. 3 Vanhellemont F. 3 Fanton-d'Andon O. 4 Barrot G. 4 Mangin A. 4 Guirlet M. 4 Blanot L. 4 Fehr T. 5 Saavedra de Miguel L. 5 Fraisse R. 6 Finnish Meteorological Institute, Earth Observation, Helsinki, Finland LATMOS/IPSL, UVSQ, CNRS-INSU, Paris, France BIRA-IASB, Brussels, Belgium ACRI ST, Sophia Antipolis, France ESA-ESRIN, Italy EADS-Astrium, Toulouse, France 08 10 2010 10 19 9505 9519 Copyright: © 2010 J. Tamminen et al. 2010 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://acp.copernicus.org/articles/10/9505/2010/acp-10-9505-2010.html The full text article is available as a PDF file from https://acp.copernicus.org/articles/10/9505/2010/acp-10-9505-2010.pdf

The Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument uses stellar occultation technique for monitoring ozone, other trace gases and aerosols in the stratosphere and mesosphere. The self-calibrating measurement principle of GOMOS together with a relatively simple data retrieval where only minimal use of a priori data is required provides excellent possibilities for long-term monitoring of atmospheric composition. <br><br> GOMOS uses about 180 of the brightest stars as its light source. Depending on the individual spectral characteristics of the stars, the signal-to-noise ratio of GOMOS varies from star to star, resulting also in varying accuracy of retrieved profiles. We present here an overview of the GOMOS data characterisation and error estimation, including modeling errors, for O<sub>3</sub>, NO<sub>2</sub>, NO<sub>3</sub>, and aerosol profiles. The retrieval error (precision) of night-time measurements in the stratosphere is typically 0.5–4% for ozone, about 10–20% for NO<sub>2</sub>, 20–40% for NO<sub>3</sub> and 2–50% for aerosols. Mesospheric O<sub>3</sub>, up to 100 km, can be measured with 2–10% precision. The main sources of the modeling error are incompletely corrected scintillation, inaccurate aerosol modeling, uncertainties in cross sections of trace gases and in atmospheric temperature. The sampling resolution of GOMOS varies depending on the measurement geometry. In the data inversion a Tikhonov-type regularization with pre-defined target resolution requirement is applied leading to 2–3 km vertical resolution for ozone and 4 km resolution for other trace gases and aerosols.

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