On the structure of background winds near the summer mesopause

Meteor wind radar observations in bistatic mode from two locations in the British Isles have led to the identification of planetary waves in the Summer season near the top of the Middle Atmosphere. By virtue of increased spatial resolution compared with traditional, monostatic radar it has been possible to identify waves with a scale size of around 4000 km and a phase speed of 12ms−1. There is some evidence for cyclonic wind motions similar to those observed in the lower atmosphere.