A ten year climatology of stratospheric gravity wave activity above southern Germany has been established recently. The climatology is based on high vertical-resolution radiosonde data of routine soundings from Munich (48N, 12E) and Stuttgart (49N, 9E) close to the northern baseline of the Alps. Four large-amplitude-wave cases are selected based on exceptional large values of energy density of stratospheric fluctuations caused by the waves. The synoptic-scale flow pattern for these cases is illustrated by ECMWF-analyses. Two characteristic features are evident for all cases: a strong north-westerly tropospheric jet stream together with a tropopause anomaly. Thus, mountains are not an important source for the stratospheric gravity waves of the selected cases since the radiosondes are launched upstream of the west-east oriented Alps. Finally, the generation and propagation of these large-amplitude-waves is studied in detail using MM5-simulations. The orographic effect of the Alps as flow barrier is inverstigated in this context and the selected cases are compared with a mountain wave case.

This study helps to better understand the sources of stratospheric large-amplitude gravity waves in the vicinity of mountains.