Wave disturbances of the atmosphere in a spatially inhomogeneous flow

Abstract

Analysis of measurements by the Dynamics Explorer 2 satellite indicates a close connection between atmospheric wave disturbances and wind circulation in the polar thermosphere. According to satellite observations, large-amplitude acoustic-gravity waves are systematically observed in the regions of formation of powerful wind systems. At the same time, the azimuths of AGW propagation are spatially consistent with the directions of wind circulation. Waves propagate mainly against the wind, and their amplitude is approximately proportional to the wind speed. In order to explain the experimental data, the paper theoretically investigated the changes in the amplitudes of AGW in a horizontally inhomogeneous wind flow. The dispersion equation of the AGW in the reference frame of the medium, which moves with a non-uniform speed, was obtained. When obtaining it, inertial forces were taken into account, as well as the change in the background density of the atmosphere in an inhomogeneous flow. It is shown that under the slow change in wind speed, the real part of this equation coincides with the dispersion equation of AGW for a stationary medium. An expression for the change in the amplitude of waves in a moving medium was obtained, according to which, in an oncoming inhomogeneous wind, the amplitude of the wave increases approximately according to a linear law, which is consistent with the data of satellite observations.