Investigation of inertia-gravity waves in the upper troposphere/lower stratosphere over Northern Germany observed with collocated VHF/UHF radars

[摘要] A case study to investigate the properties of inertia-gravity waves in the uppertroposphere/lower stratosphere has been carried out over Northern Germany during theoccurrence of an upper tropospheric jet in connection with a poleward Rossby wavebreaking event from 17-19 December 1999. The investigations are based on theevaluation of continuous radar measurements with the OSWIN VHF radar atKühlungsborn (54.1 N, 11.8 E) and the 482 MHz UHF windprofiler at Lindenberg (52.2 N, 14.1 E). Both radars are separated byabout 265 km. Based on wavelet transformations of both data sets, thedominant vertical wavelengths of about 2-4 km for fixed times as well as thedominant observed periods of about 11 h and weaker oscillations with periods of 6 h for the altitude range between 5 and 8 km are comparable. Gravitywave parameters have been estimated at both locations separately and by a complexcross-spectral analysis of the data of both radars. The results show the appearance ofdominating inertia-gravity waves with characteristic horizontal wavelengths of 300 km moving in the opposite direction than the mean background wind and asecondary less pronounced wave with a horizontal wavelength in the order of about200 km moving with the wind. Temporal and spatial differences of the observedwaves are discussed.

[学科分类] 大气科学