Features of High-Frequency Radio Wave Propagation on Auroral Paths at Different Geomagnetic Activity

Abstract

Variations in the parameters of the propagation of decameter waves on two auroral radio paths, Dikson–Pevek (D = 2800 km) and Lovozero–Pevek (D = 4200 km), were studied via oblique ionospheric sounding for two days, one weakly disturbed and one strongly disturbed. The following parameters were analyzed: F2 MOF and Es MOF (the maximum observed frequencies when the signal is reflected from the F2 layer and the Es layer), F2Spread (diffuse reflection), and lateral reflections. The following new results have been obtained: the F2 MOF level for the strongly disturbed day is higher than that for the weakly disturbed day on both paths; however, the F2 MOF values during substorms are either small or absent due to increased absorption. The Es MOF values on the Dikson–Pevek path increase during the period of disturbances. As for the Lovozero–Pevek path, the probability of Es reflections decreases during the disturbed day. The diffusion in the F2 layer on the Dikson–Pevek path is mostly typical for a strongly disturbed period, while that on the Lovozero–Pevek path, conversely, is mostly typical for weakly disturbed conditions. Lateral reflections on the Dikson–Pevek path occur rather rarely. On the Lovozero–Pevek path, there are very few lateral reflections on the weakly disturbed day and no lateral reflections on the strongly disturbed day.