Simulation of the influence of solar proton events on propagation of VLF radio signals in the polar region

The effect of proton events of various intensities on the propagation of VLF radio signals are studied by a series of computational experiments. Various events are considered, both real GLE (ground-level enhancement) 70 and 72 and fully synthetic electron density profiles. The profiles were constructed using the RUSCOSMICS and GDMI (Global Dynamic Model of Ionosphere) models developed by the PGI and IZMIRAN. Synthetic profiles obtained using the GDMI model were used as baselines for quiet conditions and subsequent obtaining of disturbed profiles. Modeling of electromagnetic signals was carried out by a numerical model of electromagnetic wave propagation developed at PGI. The signal of the model source was the sum of harmonic oscillations at the frequencies of the RSDN-20 long-range navigation radio system (11905, 12679, 14881 Hz). Amplitude damping coefficients and phase changes are calculated for GLEs of different intensities. Calculations for high-latitude and mid-latitude regions showed the presence of a latitudinal dependence of the influence of GLE events on the amplitudes and phases of the RSDN-20 signals.