VHF‐radar measurements of dynamical processes in the stratosphere and mesosphere

Radar observations in the stratosphere and mesosphere have been carried out during a minor stratospheric warming in February 1980 using the SOUSY‐VHF‐Doppler‐Radar (Germany). Enhanced echoes have been received from the stratosphere up to an altitude of about 36 km and from the mesosphere in the height range between 58 and 96 km. Aspect sensitivity has been observed at stratospheric heights, where the signal power can decrease by 10 dB between the vertical and 7° off‐vertical directions. No such effect has been observed in the mesosphere. The background wind speed and the wind direction have been deduced from Doppler measurements made in three different beam directions. The observed 3‐hour average wind speed in the stratosphere reaches a maximum of 60 m s−1, while that in the mesosphere reaches 40 m s−1. In particular, quasi‐periodic signal power variations, which are associated with vertical velocity oscillations at periods of about 12 to 15 min, have been observed in the mesosphere.