Structure of air density irregularities in the stratosphere from spacecraft observations of stellar scintillation: 1. Three-dimensional spectrum model and recovery of its parameters

The fine structure of air density irregularities at heights of 25 to 70 km was studied on the basis of stellar observations from space through the Earth's atmosphere. The results apply to the region between 40degrees S and 50degrees N. The observed occultations of stars having different positions with respect to an observer's orbital plane allowed one to study both isotropic and anisotropic components of the spatial spectra of air density fluctuations with a spatial resolution up to a few decimeters. The basic notions of the Kolmogorov turbulence in combination with an ensemble of saturated internal waves formed the basis for a model to retrieve the parameters of the three-dimensional spectra of air density irregularities in the stratosphere. To retrieve the parameters on the basis of measured spectra of stellar scintillation, the maximum likelihood method was used. It is shown that the measurement results are in good agreement with the proposed model. An analysis of the retrieval results is given in the second part of this work Characteristic Scales, Structure Characteristics, and Kinetic Energy Dissipation published in this issue of the Journal.