Aspect Sensitive Scattering of HF Radio Waves by Field-Aligned Irregularities of a Plane-Stratified Ionosphere

Abstract

Directions and radar cross-sections are calculated for aspect sensitive scattering of HF radio waves by random field-aligned irregularities of a plane-stratified (on average) ionosphere. In the calculations, the probe signal frequency is assumed to be greatly in excess of the electron gyrofrequency of the plasma layer, while lower than its critical frequency. This has allowed investigating the effect of refraction bend in the direct and reflected components of the incident and scattered electromagnetic waves neglecting the geomagnetic field effect to a process of their propagation. The suggested calculation algorithms are illustrated by the example of zenith radiation. It is shown for this geometry that with scattering height the direction of aspect scattered signal leaving the ionospheric layer approaches a vertical line, while the radar cross-section increases. It has been found that simultaneous recordings of radar cross-sections of aspect sensitive scattering from heights of critical reflection for several probe frequencies in the case of vertical incidence allow recovering the height profile of the normalization factor of the spatial spectrum of ionospheric irregularities.