Modeling HF ray trajectories and vertical and oblique ionograms in artificially disturbed ionosphere based on radiotomographic data.

The paper presents the results of numerical simulation of the propagation of HF radio waves in an artificially disturbed ionosphere during a Cyclone-3 vehicle launch from the Plesetsk cosmodrome on December 18, 1991 and a powerful industrial explosion with a magnitude of M = 2.4 on the Kola Peninsula on April 8, 1990. A specially developed set of Python scripts allows three-dimensional modeling of ray trajectories in the geometric optics approximation by solving a bicharacteristic system for eikonal equation. The developed programs use geomagnetic field from the IGRF model, and the ionospheric electron density distribution according to radio tomography data. Ionogram modeling is performed using three-dimensional homing method based on the Nelder-Mead simplex minimization. It is shown that artificial ionospheric irregularities during the periods of the studied events are quasi-wave perturbations that have a significant effect on the ray paths of the HF of radio waves and ionograms of vertical and oblique sounding. This manifests itself in the form of characteristic features of ray paths with multiple reflections from local maxima of the electron density and additional traces on ionograms caused by the passage of traveling ionospheric disturbances.