Influence of Geomagnetic Storms of September 26-30, 2011, on the Ionosphere and HF Radiowave Propagation. II. Radiowave Propagation

A study of HF wave propagation in the three-dimensional inhomogeneous ionosphere has been carried out in an approximation of geometrical optics. The three-dimensional medium of radio wave propagation is considered to be inhomogeneous, absorbing, and anisotropic due to the influence of the geomagnetic field. The parameters of the medium are described by the results of calculations on the basis of the Global Self-Consistent Model of the Thermosphere, Ionosphere, and Protonosphere (GSM TIP). The propagation of radio waves in the equatorial, middle-, and high-latitude ionosphere was studied. Comparisons of the ray trajectories, integral attenuation, deviations of the projection of radio wave trajectories onto the Earth's surface from the great-circle arc, and the behavior of the angle between the wave phase and wave energy directions, as well as the angle between the direction of propagation and the external magnetic field obtained for quiet and disturbed conditions, have been performed. We consider a geomagnetic storm that occurred in 2011, with the main storm phase occurring on September 26, and the day after geomagnetic disturbances, September 29, as disturbed conditions in the ionosphere.