A comparison of seasonal variations of gravity wave intensity observed by the MU radar with a theoretical model

A theoretical model of an ensemble of harmonics of internal gravity waves ( IGWs) propagating from random sources in the atmosphere is used to explain the seasonal variations of IGW intensity observed at different altitudes in the lower and middle atmosphere with the Japanese middle and upper atmosph ere radar. Calculations reproduce the seasonal cycles of IGW amplitudes hav ing a maximum in winter and a minimum in summer in the upper troposphere an d having maxims in winter and summer and minima at equinoxes in the mesosph ere. The seasonal behavior at different altitudes appears to be produced by the seasonal variations of the background wind and temperature, which infl uence the IGW generation, propagation, and dissipation.