Evaluation of the atmospheric transport model MEDIA using ECMWF data and using ARPEGE data during the Atmes like experiment of ETEX

During the differed time experiment of ETEX Meteo-France performed its atmospheric transport model MEDIA using both ECMWF data and a new data set provided by the french numerical weather prediction model ARPEGE. The specifications of the two meteorological data sets are strictly the same. The difference with the the real time response is that a six hours step re-analysis of the weather conditions was performed by ARPEGE to build the new data set. The results with ARPEGE data are better than during the real time response but the best simulation of the cloud displacement is obtained when we use ECMWF data. (author)