Computed HF auroral backscatter traces for various distances

Abstract

Computed ionospheric backscatter traces in the HF portion of the radio spectrum are illustrated for a number of distances between the auroral belt and the observing radar. The type, frequency range, and observed scattering height of HF auroral backscatter traces are strongly dependent upon the ionospheric propagation conditions existing between the auroral belt and the observer. Backscatter echoes produced in a given region of space by a single backscattering mechanism can have completely different range versus frequency characteristics when observed at sites located at different distances from the scattering region. Even though a given bank of auroral-belt irregularities extends through both the E and F regions, it is possible that only E-scatter is detected at one distance, and F-scatter at another. Trace type, scattering height, and frequency range of the observed backscatter echoes are strongly dependent upon the distance between the auroral belt and the observer.