Power Spectra of Ionospheric Scintillations

Abstract

Second order statistical moments of the phase fluctuations are obtained taking into account the boundary condition, diffraction effects and polarization coefficients of the ordinary and extraordinary waves. The variance and the correlation function are calculated for arbitrary 3D spectral function of electron density fluctuations containing both anisotropic Gaussian and power-law spectra; anisotropy coefficient and the orientation angle of elongated plasma irregularities. The phase scintillation index and the scintillation level are analyzed numerically. Maximum of the scintillation index for small-scale irregularities is in the interval 0.2-0.3 corresponding to the moderate scintillation intensity, within the weak-scatter regime. Splashes are revealed for different anisotropy factor of elongated largescale irregularities varying orientation angle with respect to the lines of force of geomagnetic field. Scintillation index is calculated for small-scale irregularities using the "frozenin" assumption and taking into account movement of rigid irregularities. Log-log plots of the power spectrum of the intensity fluctuations have the same minimums satisfying the "standard relationship" of scattered ordinary and extraordinary waves. It was shown that the normalized scintillation level growth in both non-fully-developed diffraction pattern and in transition zone increasing anisotropy factor. Rising orientation angle scintillation level decreases and splashes arises in fully developed scintillation region.

Statistical Moments and Scintillation Level of Scattered Electromagnetic Waves in the Magnetized Plasma

“…We choose a Cartesian coordinate system such that XY plane is the vacuum-plasma boundary; Z axis is directed in the plasma slab coinciding with the wave vector k of the refracted wave; Y Z plane (main plane) is generated by the external magnetic field vector H 0 . Components of the second rank permittivity tensor of the collisionless magnetized plasma are [11]:…”

“…is random function of the spatial coordinates; k x and k y are the spatial wave-numbers in the x and y directions, respectively. The ratio of the mean electric field components is expressed via well-known polarization coefficients: [11]:…”

Scintillation Effects in the Magnetized Plasma

“…Ionospheric irregularities have typical spatial dimensions ranging from several kilometers to few meters, are mainly field-aligned and causing scintillation. Scintillation effects of scattered ordinary and extraordinary waves in the ionospheric plasma for both power-law and anisotropic Gaussian correlation functions of electron density fluctuations have been investigated in [4][5][6][7].…”

Statistical Moments and Scintillation Level of Scattered Electromagnetic Waves in the Magnetized plasma

“…Peculiarities of the second order statistical moments of scattered radiation in collision magnetized plasma using the ray (-optics) approximation have been investigated in [6]. Statistical characteristics and scintillation level of scattered ordinary and extraordinary waves in the collision magnetized plasma normal to the external magnetic field have been considered in [7][8][9][10] using modify smooth perturbation method. Analytical and numerical calculations were carried out for the anisotropic Gaussian and power-law spectral functions taking into account diffraction effects.…”