Enhancements of gravity wave amplitudes at midlatitudes during sudden stratospheric warmings in 2008

Abstract. Two minor and one major stratospheric warming happened in January and February 2008 when the polar vortex was shifted toward midlatitudes. The analysis of temperature profiles from radiosondes in Payerne (Switzerland) during this period reveals an enhancement of gravity wave amplitudes between 25 and 30 km altitude especially during the two minor warmings around 20 January and 1 February. Increases of gravity wave amplitudes in the mid-stratosphere are associated with a strong tropopause jet and the presence of the polar vortex edge over Switzerland.