Recent topics of radiation belt science

Abstract

Highly energetic electrons in the outer radiation belt disappear during the main phase of the magnetic storm, and rebuilding of the highly energetic electrons is made during the recovery phase of the magnetic storm. The distribution of the new peak of highly energetic electron flux from the Earth is inversely proportional to the magnitude of the magnetic storm. In case of the super storm, the outer electron belt is pushed toward the Earth, filling so‐called slot region. A long‐term variation of the outer radiation belt was identified. A location of the outer radiation belt was found closer to the Earth during the solar maximum periods and far from the Earth during the solar minimum periods. A variation is due to the evidence that the large magnetic storms occur during the solar maximum periods and small magnetic storms take place during the solar minimum periods, resulting in a long‐term variation with respect to the distance from the Earth. Highly energetic electrons at geosynchronous orbit altitude are enhanced during the high‐speed solar wind velocity period. The high‐speed solar wind is mainly caused by the coronal holes and holes are evident during the declining phase of the solar activity.