On the Impact of Eddy Motions in the Mesosphere and Lower Thermosphere on the Evolution of the Signal Scattered by Artificial Periodic Irregularities

摘要

The main objective of this study is experimental diagnostics of eddy ordered structures at the altitudes of the mesosphere and upper thermosphere, such as those that occur when internal gravity waves propagate in stratified flows in the atmospheric boundary layer. To this end, we consider the impact of eddy motions in the mesosphere and lower thermosphere during relaxation of the signal scattered by periodic irregularities. The irregularities are created by a standing wave when the ionosphere is heated by high-power HF radio waves. A model of a uniform eddy with sizes exceeding the scattering volume is used. A relation between the eddy period and the characteristic time of relaxation of scattered signal, for which the synchronism of the waves scattered by a periodic structure is broken, is found. This, in turn, decreases the amplitude of the scattered signal and its relaxation time. Experimental data on atmospheric turbulence obtained by the resonant scattering technique are presented.