Recovery of Spectral Properties of Acoustic-Gravity Waves in Satellite Measurements

Abstract

Acoustic-gravity waves (AGWs) are the important mechanism for transferring energy in the atmosphere from the Earth and space disturbances. Theresult of the expansion of AGWs is the fluctuations of atmospheric parameters, which can be registered by ground-based and satellite measurements.However, each of the methods has certain limitations on obtaining information about the properties of the waves. In this regard, it is important thedevelopment of methods which allow us to recover the spectral properties ofAGWs on the basis of limited experimental data. In this article, an analyticalmethod for determining the spectral properties of acoustic-gravity wavesfrom direct satellite measurements is proposed. The method is based on polarization relations, which connect the wave fluctuations of different atmospheric parameters (temperature, density and velocity of particles). It is basedon the determination of the phase shifts between oscillations of some physical parameters of the atmosphere, which are available in satellite measurements. Simple analytical relations are obtained, which allow us to determinethe spectral characteristics of AGW, the nature of wave propagation (horizontal or freely propagated at an angle to the horizontal plane) and their direction relative to the satellite. It is shown that the feature of evanescentwaves is in-phase or anti-phase oscillations of density and temperature. Infreely propagating AGH, these oscillations have a certain phase shift, themagnitude of which depends on the spectral properties. The results obtainedin this work allow us to determine immediately the type of the waves towhich the observed atmospheric perturbation belongs. According to the experimental data, the proposed method for determining the AGW spectralcharacteristics of AGWs has been tested. For this purpose, the measurements of atmospheric AGW parameters in the polar regions on the Dynamics Explorer 2 satellite were used.