Background Wind Effect on the Diurnal Tide in the Middle Atmosphere

Abstract

Numerical calculation of the atmospheric diurnal tide in the middle atmosphere has been carried out for the equinoctial condition with emphasis on the effect of latitudinal temperature gradient and background mean zonal wind. It is shown that in the mid-to-low latitude region, propagating (1, 1) mode is affected, especially in its phase, by the equinoctial westerly wind and phase lag at 90km is 4-5 hours relative to the no wind condition. The result might account for part of the tidal variability observed in the mesosphere and lower thermosphere.