Journal article
Characterization and Evolution of Radiation Belt Electron Energy Spectra Based on the Van Allen Probes Measurements
Journal of geophysical research. Space physics, Vol.124(6), pp.4217-4232
06/2019
DOI: 10.1029/2019JA026697
Abstract
Based on the measurements of ~100‐keV to 10‐MeV electrons from the Magnetic Electron Ion Spectrometer (MagEIS) and Relativistic Electron and Proton Telescope (REPT) on the Van Allen Probes, the radiation belt electron energy spectra characterization and evolution have been investigated systematically. The results show that the majority of radiation belt electron energy spectra can be represented by one of three types of distributions: exponential, power law, and bump‐on‐tail (BOT). The exponential spectra are generally dominant in the outer radiation belt outside the plasmasphere, power law spectra usually appear at high L‐shells during injections of lower‐energy electrons, and BOT spectra commonly dominate inside the plasmasphere at L>2.5 during relatively quiet times. The main features of three types of energy spectra have also been revealed. Specifically, for the BOT energy spectrum, the energy of local flux maximum usually ranges from approximately hundreds of keV to several MeV and the energy of local flux minimum varies from ~100 keV to ~MeV, both increasing as L‐shell decreases, confirming the plasmaspheric hiss wave scattering to be the main mechanism forming the BOT energy spectra. Statistical results using 4‐year observations from the Van Allen Probes on the relation between energy spectra and plasmapause location also show that the plasmasphere plays a critical role in shaping radiation belt electron energy spectrum: the peak location of BOT energy spectra is ~1 L‐shell inside the minimum plasmapause, where BOT energy spectra mostly form in ~1–2 days as a result of hiss wave scattering.
Key Points
Most radiation belt electron energy spectra can be represented by one of three distributions: exponential, power law, and bump‐on‐tail
Exponential spectra dominate outside the plasmasphere; power law spectra often appear at high L during injections of lower‐energy electrons
Bump‐on‐tail spectra dominate inside the plasmasphere at L<2.5 and are caused by hiss wave scattering
Details
- Title: Subtitle
- Characterization and Evolution of Radiation Belt Electron Energy Spectra Based on the Van Allen Probes Measurements
- Creators
- H. Zhao - Laboratory for Atmospheric and Space PhysicsW. R. Johnston - Kirtland Air Force BaseD. N. Baker - Laboratory for Atmospheric and Space PhysicsX. Li - Laboratory for Atmospheric and Space PhysicsB. Ni - Wuhan UniversityA. N. Jaynes - University of IowaS. G. Kanekal - Goddard Space Flight CenterJ. B. Blake - The Aerospace CorporationS. G. Claudepierre - University of California, Los AngelesG. D. Reeves - New Mexico ConsortiumA. J. Boyd - New Mexico Consortium
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.124(6), pp.4217-4232
- DOI
- 10.1029/2019JA026697
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Number of pages
- 16
- Grant note
- NASA (NAS5‐01072) JHU/APL (967399) Hubei Province Natural Science Excellent Youth Foundation (2016CFA044) NSFC (41474141; 41674163)
- Language
- English
- Date published
- 06/2019
- Academic Unit
- Physics and Astronomy; University College Courses
- Record Identifier
- 9984429013102771
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