Inertia-gravity waves in the troposphere and lower stratosphere associated with a jet stream exit region

摘要

Radar measurements at Aberystwyth (52.4°N, 4.1° W) of winds at tropospheric and lower stratosphericheights are shown for 12-13 March 1994 in a region of highly curved flow,downstream of the jet maximum. The perturbations of horizontal velocity havecomparable amplitudes in the troposphere and lower stratosphere with downwardand upward phase propagation, respectively, in these two height regions. Thesense of rotation with increasing height in hodographs of horizontalperturbation velocity derived for hourly intervals show downwards propagation ofenergy in the troposphere and upward propagation in the lower stratosphere withvertical wavelengths of 1.7 to 2.3 km. The results indicate inertia-gravitywaves propagating in a direction similar to that of the jet stream but atsmaller velocities. Some of the features observed contrast with those ofprevious observations of inertia-gravity waves propagating transverse to the jetstream. The interpretation of the hodographs to derive wave parameters has takenaccount of the vertical shear of the background wind transverse to the directionof wave propagation.Key words. Meteorology and atmospheric dynamics(mesoscale meteorology; middle atmosphere dynamics; waves and tides)