Distribution of mean Doppler shift, spectral width, and skewness of coherent 50‐MHz auroral radar backscatter

Abstract

Some 7700 radio aurora spectra obtained from a six link 50‐MHz CW radar network set up on the Canadian prairies were analyzed with respect to the distributions of mean Doppler shift, spectral width and skewness. A comparison with recently published SABRE results obtained at 153 MHz (Schlegel et al., 1986) shows substantial differences in the distributions which are probably due to different experimental and geophysical conditions. Our spectra are mostly broad with mean Doppler shifts close to zero (type II spectra). The typical groupings of type I and type III spectra are clearly identified. All types appear to be in general much more symmetric than those recorded with SABRE, and the skewness is only weakly dependent on the sign of the mean Doppler shift. Its distribution peaks near zero and shows a weak positive correlation with the type II Doppler shifts while the mostly positive type I Doppler shifts are slightly negatively correlated with the skewness.