Concurrent relativistic electron enhancements and deep penetration of ULF waves into the inner magnetosphere
Abstract
Geospace magnetic storms are associated with both enhancements and losses of the outer Van Allen belt electrons. Enhancements of relativistic electrons have been shown to be closely linked to solar wind speed and density increases as well as to prolonged intervals of southward interplanetary magnetic field. Individual case studies have demonstrated that ULF waves deep in the magnetosphere may contribute significantly to outer belt enhancements. In the present study, which is centered around the maximum of solar cycle 24, we use GOES geostationary orbit electron flux observations, along with electron and electromagnetic field data from the Van Allen Probes, to study radiation belt electron acceleration during the course of moderate and intense magnetic storms. We compare relativistic and ultra-relativistic electron observations with the concurrent latitudinal and azimuthal distributions of wave power enhancements at Pc5 frequencies as detected by a global network of ground magnetic stations. During the main phase of magnetic storms, there is a marked penetration of Pc5 wave power to low L shells, especially during storms characterized by increased post-storm electron fluxes as compared to their pre-storm values. VLF waves may also play a role in enhancing the outer belt electron population. We discuss the growth and decay characteristics of waves in association with the interplanetary coronal mass ejections.
- Publication:
-
41st COSPAR Scientific Assembly
- Pub Date:
- July 2016
- Bibcode:
- 2016cosp...41E.655G