EFFECT OF THE WAVE SHEAR INTERACTION ON GRAVITY-WAVE ACTIVITY IN THE LOWER AND MIDDLE ATMOSPHERE

Observational results of the wave activities and the vertical wave number spectra of the horizontal wind fluctuations and the temperature density fluctuations in the lower and middle atmosphere obtained by various groups using different instruments at different locations are reviewed and summarized. Then, we use a simple analytic model of wave shear interaction to explain the wave-energy dissipation observed in the stratosphere/lower mesosphere. the east west anisotropy of the wave propagation. and the deceleration of the zonal mean flow, in summer and in winter in the middle mesosphere, the annual variation in the upper troposphere/stratosphere/lower mesosphere. and the semi-annual variation in the middle mesosphere. We also point out that the saturation spectra observed in the middle mesosphere and the winter troposphere are caused by wave motions in the strong background wind shear and the low stability temperature profile, and that the saturation spectrum is universally N2/2m3 (where N is the Brunt Vaisala frequency and m is the vertical wave number).