On the accuracy of stratospheric meteorological reanalyses using wind measurements at high altitude in the stratosphere in polar and equatorial regions.

Abstract:

This study is motivated by the improvement of the knowledge of stratospheric dynamics and the evaluation of the ability of models to represent wind variability in the stratosphere. We deduce from the Zero Pressure balloons trajectories, operated by CNES during the last decade, zonal and meridional wind components to provide an unique database in the altitude range [25-40] km. The collected data cover various seasons and locations in polar region above the Esrange (Sweden) launch base (67.9°N, 23.1°E) and Tropics above the Teresina (Brazil) launch base (5.1°, 42.9°W). We performed comparisons between wind measurements and ERA–interim reanalysis from ECMWF (European Centre for Medium-Range Weather Forecasts). We will present the systematically evaluation of the accuracy of the ERA–interim reanalyzes up to 40 km and performed in several geophysical conditions (winter and summer in polar region, and in the equatorial East and West phase of the Quasi Biennale Oscillation).We identify large discrepancies: above 30 km in Polar region, and in the equatorial region where a large wave activity is recorded. Results presented will help for better understanding and improving the stratospheric circulation representation used by the models.