Spectral characteristics of ionospheric scintillations of UHF radiosignal near magnetic zenith

Abstract

We present results of observation of Cygnus-A radiosource scintillation in the Earth's ionosphere in quiet and disturbed geomagnetic condition at Irkutsk incoherent scattering radar (IISR). Scintillation method applied for ionosphere testing at IISR confidently defines Fresnel frequency and power cutoff - the spectral characteristics usually related to the velocities and spatial spectra of ionospheric plasma irregularities. We also use IGFR magnetic field model in order to show relation between shape of discrete radio source scintillation spectra and direction to the radio source with respect to geomagnetic field. Observed increasing of S4 index in magnetic zenith is conditioned by the scintillation spectrum widening. We also evaluate zonal velocity of observed ionospheric irregularities as ~10 m/sec assuming irregularities to appear at the height of F2 layer maximum of the ionosphere.