Propagation of HF radiowaves on high-latitude radio paths during the magnetically disturbed period of October 24–28, 2003

Abstract

The behavior of the HF signal parameters during magnetic storms and substorms has bee experi� mentally studied simultaneously on the Kiruna-Kirkenes auroral path, Kiruna-Longyearbyen polar path, and Murmansk-St. Petersburg subauroral path. The first two paths are equipped with the instruments making it possible to measure the values of the signaltonois e ratio, Doppler frequency shift, and elevation angle. The method of oblique sounding of the ionosphere (OSI) was used on the Murmansk-St. Petersburg path. Two substantial substorms, a moderate storm, and an intense storm occurred during the studied period. Some new regularities have been revealed. On the Kiruna-Kirkenes and Kiruna-Longyearbyen paths, the signal� tonoise ratio increased (due to the transition from the F2 signal reflections to the Es reflections), the elevation angle increased (due to an increase in the ionospheric F2 layer height and a decrease in the critical frequency), and the Doppler shift increased (due to the variations in ionization and the appearance of ionospheric irreg� ularities during a substorm) when the signal was reflected from the F 2 layer close to the moment of the sub� storm or storm beginning T0. It is possible to control the socall ed "main effect" in the ionosphere on the Murmansk-St. Petersburg path.