Gravity wave motions in the upper middle atmosphere (60-110 km)

Abstract

Recent improvements in radar techniques have significantly increased their potential for inves- tigating internal atmospheric gravity waves propagating in the upper mesosphere and lower thermosphere. Information relating to the upward flux of horizontal momentum, and hence the mean flow acceleration associated with these waves, is now accessible, as are better estimates of horizontal scales and phase velocities. Long term single site measurements of horizontal velocity have also allowed seasonal variations in mean square velocity components associated with gravity waves to be investigated. Recent results obtained with the Adelaide, Australia (35°S), and Saskatoon, Canada (52°N), MF radars are briefly considered, together with related observations derived from other techniques.