Calculation of Geomagnetic Cutoff Rigidity Using Tracing Based on the Buneman–Boris Method

The article develops a method for determining the geomagnetic cutoff rigidity based on tracing of charged particles in Earth’s magnetic field using the particle-in-cell method implemented in the Buneman–Boris scheme. In order to test the method, the geomagnetic cutoff rigidity in the field of an ideal dipole and in the field given by the IGRF model are calculated. In the first case, the obtained data are compared with analytical values. The calculation accuracy in this case is 3 MV. In the second case, the penumbra pattern is reproduced in different geographical locations, for different periods, and the stability of the method to small perturbations of the initial parameters is investigated. As the main results, the article constructs and analyzes geomagnetic cutoff rigidity maps at low-orbit satellite altitudes for different directions in space as well as their variations from 1900 to 2015.