A method for operative calculation of charged particle penetration into the LEO

We develop a simple method for calculating the effective vertical cutoff rigidity of charged particles, taking into account the Kp-index and the local time, on the basis of generalization of the results of extensive trajectory calculations for trial particles moving in the geomagnetic field. The vertical cutoff rigidities, calculated by the Tsyganenko-89 model, are presented as an International Geomagnetic Reference Field (IGRF) model calculated and thereafter corrected in accordance with the geomagnetic disturbance and local time conditions. The fits from the proposed method agree with the results of cutoff rigidity measurements carried out by satellites. The method is intended for applications using cutoff calculations, such as evaluating particle penetration of spatial boundaries, calculating magnetospheric transmissions for low-orbital spacecrafts flights and interpreting the results of orbital experiments.