| Summary: | International audience This study consists to retrieve wind data from trajectories of balloon flights, which can be considered as perfect tracers at high levels ( above 25 km), to provide an assessment of meteorological wind data coming from Era-interim Re-analysis and forecastsfrom ECMWF. We first present our database including 327 balloon flights from 1989 to 2011 and validate the methodology to deduce zonal and meridional winds. Balloon flights were operated by the CNES (French Spatial Agency). The large stratospheric balloons can reach ceilings in the range 25-40 km and the flight durations are from few hours to several days. The collected database covers various seasons and different locations: Polar region (Kiruna (North of Sweeden)), Mid-latitudes (Gap and Aire-sur-Adour (France)) and Tropics (Hawaii, Teresina and Bauru (Brazil), Niamey (Niger)). Geophysical conditions we analyze are: polar vortex, spring and summer turn around in polar region, mid-latitude circulation in spring and autumn, and in the tropic East and West phase of the Quasi Biennale Oscillation.The first goal of this study is evaluate the vertical variability of the wind (intensity and direction) at high altitude in order to improve Balloon trajectory forecasts during measurement campaign to help for the flight decision and drive the balloon during the flight, which is a major goal for the safety related for future balloon campaign. The second goal is to evaluate the ability of ECMWF model to represent and predict winds and the circulation in the mid-stratosphere. The method used to compare ECMWF results and wind measurement is presented including methodology for interpolating ECMWF results on our data grid. Whatever the region /season considered, preliminary results obtained highlight bias between Era-interim Re-analysis and our wind data. In the future we plan to extend our study to operational wind data from ECMWF.
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