Spectra and Pitch-Angular Distributions of Relativistic Electrons Near the Outer Radiation Belt Maximum During the Magnetic Storm of December 19–22, 2015

Abstract

Variations in the spectra and pitch-angle distribution of relativistic electrons are studied for the large magnetic storm on December 19–22, 2015, during which the position of the electron trapping boundary with an energy >100 keV was recorded inside the auroral oval according to the Meteor-M No. 2 satellite. The results of ECT-REPT observations in the RBSP/Van Allen Probes mission near the maximum of the newly formed belt are used. Changes in the spectra and pitch-angle distributions as a result of the development of individual substorms during the storm are considered. The results support effective particle acceleration at relatively short time scales (<6 h). The role of the adiabatic mechanism in the acceleration and loss of relativistic electrons is considered. Evidence has been obtained for the dominant role of processes at the latitudes of the auroral oval in the formation of the outer radiation belt.