SIMULATION OF THE INFLUENCE OF STATIONARY PLANETARY-WAVES ON THE ZONALLY AVERAGED CIRCULATION OF THE MESOSPHERE LOWER THERMOSPHERE REGION

A linearised numerical model has been used to simulate the stationary planetary waves (SPW) structure and investigate its influence on a zon ally averaged circulation in the mesosphere and lower thermosphere. Th e wave-activity density, Eliassen-Palm flux, and its divergence cross- sections are used as a diagnostic of wave propagation and wave-mean do w interaction. The results of numerical simulations show that SPW can provide the substantial accelerations of the mean flow which are compa rable with the accelerations due to the breakdown of internal gravity waves and atmospheric tides, and it is necessary to develop three-dime nsional models of the general circulation of the lower thermosphere, t aking account of the effects of gravity wave and tidal drag. The influ ence of the eddy thermal conduction and viscosity on the formation of SPW structure in the mesosphere and lower thermosphere and on the dist ribution of the mean flow accelerations due to SPW dissipation is disc ussed.