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Assimilation of GOME total‐ozone satellite observations in a three‐dimensional tracer‐transport model

A data‐assimilation scheme to assimilate the Global Ozone Monitoring Experiment (GOME) total‐ozone data is described. The corresponding software (called TM3DAM) has been operational since early 2000 and is used to produce daily ozone analyses and five‐day ozone forecasts. The model is a tracer‐transport model with a parametrized description of stratospheric gas‐phase and heterogeneous ozone chemistry. It is driven by operational meteorological fields from the ECMWF numerical weather‐prediction model. TM3DAM analyses near‐real‐time level‐2 ozone data from the GOME instrument on the ESA ERS‐2 satellite. The focus of this paper is on the data‐assimilation aspects and the analysis results. The assimilation approach is based on the Kalman‐filter equations and provides detailed and realistic maps of the forecast error. The analysis scheme is nevertheless computationally efficient. The forecast‐minus‐observation statistics, accumulated over a two‐year period, are described in detail. A comparison with TOMS and Brewer observations shows good agreement. Copyright © 2003 Royal Meteorological Society