Seasonal Features of the Spatial Distribution of Atmospheric Gravity Waves in the Earth’s Polar Thermosphere

Abstract

The features of the spatial distribution of atmospheric gravity waves (AGW) in the polar thermosphere of the Earth are investigated. The research is based on data from direct satellite measurements of the parameters of the neutral atmosphere. According to satellite data, the amplitudes of AGWs that are systematically observed in the polar regions of both hemispheres are usually several times higher than the amplitudes of these waves in the middle and low latitudes. At the same time, the polar AGWs of large amplitudes are recorded against the background of high-speed spatially inhomogeneous wind flows, which indicates their possible amplification caused by interaction with the wind. Based on the analysis of measurement data on the Dynamics Explorer 2 satellite, the relationship between the spatial distribution of the atmospheric gravitational waves and the auroral oval has been revealed. On a large volume of experimental data, seasonal patterns of the distribution of the wave field over the Antarctic and the Arctic have been established. A comparative analysis of the features of the AGWs in the polar thermosphere of both hemispheres for the conditions of the polar day and polar night has been carried out. Some differences in the distribution of the AGWs were noted depending on the Kp-index. It has been suggested that the observed seasonal features of the AGW distribution and its dependence on the level of geomagnetic activity are associated with the restructuring of the polar wind circulation when the conditions of solar illumination and geomagnetic conditions change.