A magnetosphere model based on two zones of precipitating energetic particles

Abstract

Contrary to widely held ideas on the oval zone of precipitation of energetic particles into the earth's atmosphere, the existence of two quasi-circular zones of precipitation was established several years ago on the basis of geomagnetic activity data. The two zones were found to be of quite a different nature. One of these zones, the higher-latitude one, has its maximum on the day side (latitude ∼77°); the other zone, the lower-latitude one, has a considerably longer latitudinal extension and has its maximum on the night side (latitude ∼67°). The concept of the oval zone as a single unified zone is not a necessary conclusion and could be a result of insufficient data or of incorrect data reduction. The same conclusion can also be reached on the basis of the analysis performed by Feldstein himself and on the basis of other direct and indirect data. In this paper the main features of two quasi-circular zones are presented on the basis of the instantaneous patterns of the distribution of geomagnetic activity as well as on the basis of the dynamics of these patterns. A magnetosphere model reflecting these features is presented. The suggested model links the lower-latitude zone with processes occurring in the magnetospheric tail, whereas the higher-latitude zone is connected with particle injection through the neutral points.