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- Title
Van Allen Probes Observations of Multi‐MeV Electron Drift‐Periodic Flux Oscillations in Earth's Outer Radiation Belt During the March 2017 Event.
- Authors
Zhao, Hong; Sarris, Theodore E.; Li, Xinlin; Weiner, Max; Huckabee, Isabela G.; Baker, Daniel N.; Jaynes, Allison J.; Kanekal, Shrikanth G.; Elkington, Scot R.; Barani, Mohammad; Tu, Weichao; Liu, Wenlong; Zhang, Dianjun; Hartinger, Michael D.
- Abstract
Radiation belt electrons undergo frequent acceleration, transport, and loss processes under various physical mechanisms. One of the most prevalent mechanisms is radial diffusion, caused by the resonant interactions between energetic electrons and ULF waves in the Pc4‐5 band. An indication of this resonant interaction is believed to be the appearance of periodic flux oscillations. In this study, we report long‐lasting, drift‐periodic flux oscillations of relativistic and ultrarelativistic electrons with energies up to ∼7.7 MeV in the outer radiation belt, observed by the Van Allen Probes mission. During this March 2017 event, multi‐MeV electron flux oscillations at the electron drift frequency appeared coincidently with enhanced Pc5 ULF wave activity and lasted for over 10 h in the center of the outer belt. The amplitude of such flux oscillations is well correlated with the radial gradient of electron phase space density (PSD), with almost no oscillation observed near the PSD peak. The temporal evolution of the PSD radial profile also suggests the dominant role of radial diffusion in multi‐MeV electron dynamics during this event. By combining these observations, we conclude that these multi‐MeV electron flux oscillations are caused by the resonant interactions between electrons and broadband Pc5 ULF waves and are an indicator of the ongoing radial diffusion process during this event. They contain essential information of radial diffusion and have the potential to be further used to quantify the radial diffusion effects and aid in a better understanding of this prevailing mechanism. Key Points: Long‐lasting, drift‐periodic flux oscillations of 1.8–7.7 MeV electrons in the radiation belt are reported using Van Allen Probes dataFlux oscillations appeared coincidently with enhanced Pc5 ULF waves with amplitude well correlated with phase space density radial gradientThese flux oscillations indicate the resonant interactions between electrons and broadband Pc5 ULF waves
- Subjects
RADIATION belts; ELECTRONS; RELATIVISTIC electrons; VAN Allen radiation belts; PHASE space
- Publication
Journal of Geophysical Research. Space Physics, 2021, Vol 126, Issue 8, p1
- ISSN
2169-9380
- Publication type
Article
- DOI
10.1029/2021JA029284