Journal article
The Effects of Geomagnetic Storms and Solar Wind Conditions on the Ultrarelativistic Electron Flux Enhancements
Journal of geophysical research. Space physics, Vol.124(3), pp.1948-1965
03/2019
DOI: 10.1029/2018JA026257
Abstract
Using data from the Relativistic Electron Proton Telescope on the Van Allen Probes, the effects of geomagnetic storms and solar wind conditions on the ultrarelativistic electron (E > ~3 MeV) flux enhancements in the outer radiation belt, especially regarding their energy dependence, are investigated. It is showed that, statistically, more intense geomagnetic storms are indeed more likely to cause flux enhancements of ~1.8‐ to 7.7‐MeV electrons, though large variations exist. As the electron energy gets higher, the probability of flux enhancement gets lower. To shed light on which conditions of the storms are preferred to cause ultrarelativistic electron flux enhancement, detailed superposed epoch analyses of solar wind parameters and geomagnetic indices during moderate and intense storms with/without flux enhancements of different energy electrons are conducted. The results suggest that the storms with higher solar wind speed, sustained southward interplanetary magnetic field Bz, lower solar wind number density, higher solar wind Ey, and elevated and sustained substorm activity are more likely to cause ultrarelativistic electron flux enhancements in the outer belt. Comparing results of different energy electrons, the solar wind speed and AE index are the two parameters mostly correlated with the energy‐dependent acceleration of ultrarelativistic electrons: Storms with higher solar wind speed and elevated and sustained substorm activity are more likely to cause flux enhancement of ultrarelativistic electrons with higher energies. This suggests the important roles of inward radial diffusion as well as the source and seed populations provided by substorms on the energy‐dependent acceleration of ultrarelativistic electrons.
Key Points
Probability of ultrarelativistic electron flux enhancement is higher during more intense storms and for electrons with lower energies
Storms with high solar wind speed, low number density, and sustained southward Bz are likely to cause ultrarelativistic electron enhancement
High solar wind speed and sustained substorm activity are most influential to energy‐dependent acceleration of ultrarelativistic electrons
Details
- Title: Subtitle
- The Effects of Geomagnetic Storms and Solar Wind Conditions on the Ultrarelativistic Electron Flux Enhancements
- Creators
- H Zhao - University of Colorado BoulderD. N Baker - University of Colorado BoulderX Li - University of Colorado BoulderA. N Jaynes - University of IowaS. G Kanekal - Goddard Space Flight Center
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.124(3), pp.1948-1965
- DOI
- 10.1029/2018JA026257
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Number of pages
- 18
- Grant note
- NASA (NAS5‐01072) JHU/APL (967399) RBSP‐ECT
- Language
- English
- Date published
- 03/2019
- Academic Unit
- University College Courses; Physics and Astronomy
- Record Identifier
- 9984199820202771
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