Strong scintillation spectra behind the atmosphere with large- and small-scale inhomogeneities

Abstract

The numerical examination of 2D spectra of strong stellar scintillations observed through the Earth’s atmosphere from space is carried out. The atmosphere contains a combination of statistically independent, anisotropic large-scale and isotropic small-scale inhomogeneities of the refractive index. 2D spectra and vertical and horizontal 1D spectra calculated using them are presented. It is shown that the strong scintillation spectra are not equal to the sum of the spectra formed by separate, statistically independent components. The combination of large- and small-scale inhomogeneities results in a greater dispersion of scintillations in comparison with the absence of latter ones. However, the presence of this combination can lead both to an increase and decrease of dispersion in comparison with the sum of dispersions of the anisotropic and isotropic components depending on their intensity relation. The new effect in 1D horizontal spectra behavior is found in the region of small wave numbers; i.e., the presence of small-scale atmospheric inhomogeneities results in the suppression of spectral power of scintillation formed by only an anisotropic component.