Vol. 17, issue 10, article # 3

Kan V. Coherence and correlation of chromatic stellar scintillations in a spaceborne occultation experiment. // Atmospheric and oceanic optics. 2004. V. 17. No. 10. P. 725-735.
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The model spectra and correlation functions of chromatic stellar scintillations are calculated for synchronous sensing of the Earth's atmosphere at different wavelengths. The model 3D spectrum of air refractivity fluctuations, describing anisotropic and isotropic inhomogeneities, is used. The calculations are performed in the approximations of the equivalent phase screen and weak scintillations. Weak scintillations for low-orbit satellites (Mir station, European ENVISAT/GOMOS satellite) are realized for altitudes of ray perigee above 25-30 km. The scintillation characteristics are shown to depend essentially on the geometry and observation conditions, in the first turn, on the direction of atmospheric sensing. Coherence spectra allow specifying the range of effectively vertical and horizontal sensing angles in atmosphere. The anisotropy coefficient of inhomogeneities can be estimated from autospectra and coherence spectra for effectively horizontal sensing. A set of chromatic scintillation spectra for different atmospheric cross sections allows estimating the main statistical characteristics of atmospheric inhomogeneities in the altitude range 30-70 km. The use of scintillation correlation at different wavelengths allows reducing the errors caused by "scintillation noise" when recovering the concentrations of minor atmospheric constituents in spectrometric star occultation technique. On the basis of analysis of chromatic scintillation spectra and correlation functions, the recommendations for optimum planning of satellite observations are worked out for monitoring of the statistical structure of inhomogeneities and the concentrations of atmospheric constituents.