Rapid Enhancements of the Seed Populations in the Heart of the Earth's Outer Radiation Belt: A Multicase Study

TitleRapid Enhancements of the Seed Populations in the Heart of the Earth's Outer Radiation Belt: A Multicase Study
Publication TypeJournal Article
Year of Publication2018
AuthorsTang, CL, Xie, XJ, Ni, B, Su, ZP, Reeves, GD, Zhang, J-C, Baker, DN, Spence, HE, Funsten, HO, Blake, JB, Wygant, JR, Dai, GY
JournalJournal of Geophysical Research: Space Physics
Date Published06/2018
Keywordsenhanced convection; Substorm Injections; the outer radiation belt; the seed population; ULF waves; Van Allen Probes
AbstractTo better understand rapid enhancements of the seed populations (hundreds of keV electrons) in the heart of the Earth's outer radiation belt (L* ~ 3.5–5.0) during different geomagnetic activities, we investigate three enhancement events measured by Van Allen Probes in detail. Observations of the fluxes and the pitch angle distributions of energetic electrons are analyzed to determine rapid enhancements of the seed populations. Our study shows that three specified processes associated with substorm electron injections can lead to rapid enhancements of the seed populations, and the electron energy increases up to 342 keV. In the first process, substorm electron injections accompanied by the transient and intense substorm electric fields can directly lead to rapid enhancements of the seed populations in the heart of the outer radiation belt. In the second process, the substorm injected electrons are first trapped in the outer radiation belt and subsequently transported into L* < 4.5 by the convection electric field. In the third process, the lower energy electrons are first injected at L* ~ 5.3 and then undergo drift resonance with ultralow‐frequency waves. These accelerated electrons by ultralow‐frequency waves are further transported into L* < 4.5 due to the convection electric field. This process is consistent with the radial diffusion. Our results suggest that these specified processes are important for understanding the dynamics of the seed populations in the heart of the outer radiation belt.
URLhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2017JA025142
DOI10.1029/2017JA025142
Short TitleJ. Geophys. Res. Space Physics


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