Atmospheric Tidal Motions over Australia below 20 Kilometers

Abstract

The diurnal and semidiurnal variations of the wind have been computed from 12 years of upper wind observations at Australian stations. The strong diurnal oscillation in the boundary layer over the continent is remarkably constant in phase and appears to interact with the sea breeze oscillations at the coast. Above a transition layer of varying thickness, a layer of roughly constant phase extends through much of the troposphere. Vertically propagating modes dominate the diurnal tide above 16 km, transferring energy upward. In contrast to the diurnal tide, the semidiurnal tide (except in the boundary layer) is almost independent of height up to at least 13 km, also of season and geographical position.