Power Spectra of Ionospheric Scintillations

B Rawat,A Ishimaru,O Kharshiladze,Z Diasamidze,G V Jandieri

doi:10.7716/aem.v6i4.652

Abstract

Second order statistical moments of the phase fluctuationsare obtained taking into account the boundary condition,diffraction effects and polarization coefficients of theordinary and extraordinary waves. The variance and thecorrelation function are calculated for arbitrary 3D spectralfunction of electron density fluctuations containing bothanisotropic Gaussian and power-law spectra; anisotropycoefficient and the orientation angle of elongated plasmairregularities. The phase scintillation index and thescintillation level are analyzed numerically. Maximum ofthe scintillation index for small-scale irregularities is in theinterval 0.2-0.3 corresponding to the moderate scintillationintensity, within the weak-scatter regime. Splashes arerevealed for different anisotropy factor of elongated largescaleirregularities varying orientation angle with respect tothe lines of force of geomagnetic field. Scintillation index iscalculated for small-scale irregularities using the “frozenin”assumption and taking into account movement of rigidirregularities. Log-log plots of the power spectrum of theintensity fluctuations have the same minimums satisfyingthe “standard relationship” of scattered ordinary andextraordinary waves. It was shown that the normalizedscintillation level growth in both non-fully-developeddiffraction pattern and in transition zone increasinganisotropy factor. Rising orientation angle scintillation leveldecreases and splashes arises in fully developedscintillation region.

Highlights

At the present time the features of radio waves propagation in random media have been rather well studied
The present paper reports the results of an analysis of the power spectrum of ionospheric scintillation data, which is related to fluctuations in the radio refractive index in the F region
Maximum S4 max is in the interval 0.2-0.3 indicating conditions of weak scatter of the radio wave by the ionospheric irregularities

Summary

Introduction

At the present time the features of radio waves propagation in random media have been rather well studied. Second order statistical moments of the phase fluctuations were calculated considering polarization coefficients of both ordinary and extraordinary waves in the turbulent collision magnetized plasma and the diffraction effects. Analytical and numerical investigations were carried out in the ionospheric F region for the Gaussian spectral function of electron density fluctuations Scintillation effects in this region were investigated for the small-scale ionospheric irregularities [8]. Scintillation minimums of a temporal spectrum are calculated for different thicknesses of a plasma slab taking into account the movement of rigid irregularities and diffraction effects for scattered ordinary and extraordinary waves in turbulent magnetized plasma [9]. Analytical and numerical calculations of the second order statistical moments of scattered radio waves in the magnetized ionospheric plasma are carried out taking into account diffraction effects. Numerical calculations are based on the experimental data of the navigation satellites

Formulation of the Problem

Numerical Calculations

Conclusions