Identification of acoustic-gravity waves from satellite measurements

Abstract

A method for recognizing the types of linear acoustic gravity waves (AGWs) in the atmosphere from satellite measurements is proposed. It is shown that the polarization relations between fluctuations of wave parameters (velocity, density, temperature, and pressure) for freely propagating waves, as well as evanescent wave modes, differ significantly, which makes it possible to identify different types of atmospheric waves in experimental data. A diagnostic diagram is proposed, with the help of which, from the phase shifts of the observed parameters, it is possible to determine the type of wave, as well as the direction of its movement relative to the vertical. Using phase shifts between fluctuations of the velocity and thermodynamic parameters of the atmosphere, not only the type of the wave, but also its spectral characteristics can be determined. The verification of the proposed method for identification of polar wave disturbances in measurements from the low-orbit satellite Dynamics Explorer 2 was carried out. The verification showed that the polarization relations of AGW in the thermosphere mainly correspond to the gravity branch of acoustic-gravity waves freely propagating in the direction from bottom to top. This conclusion is consistent with other results of AGW observations in the atmosphere and ionosphere by ground-based and satellite methods. No evanescent waves were observed on the considered orbits.