Sub-MeV electron precipitation driven by EMIC waves in plasmaspheric plumes at high L-shells
Files
Accepted manuscript
Date
2023-06-14
Version
Accepted manuscript
OA Version
Citation
M. Qin, W. Li, Y. Nishimura, S. Huang, Q. Ma, L. Capannolo, X. Shen, V. Angelopoulos, A. Artemyev, M. Hanzelka, L. Gan. 2023. "Sub-MeV Electron Precipitation Driven by EMIC Waves in Plasmaspheric Plumes at High L-shells" Journal of Geophysical Research (JGR): Space Physics. https://doi.org/10.1029/2025ja033756
Abstract
Electromagnetic ion cyclotron (EMIC) waves are known to be efficient for precipitating >1 MeV electrons from the magnetosphere into the upper atmosphere. Despite considerable evidence showing that EMIC‐driven electron precipitation can extend down to sub‐MeV energies, the precise physical mechanism driving sub‐MeV electron precipitation remains an active area of investigation. In this study, we present an electron precipitation event observed by ELFIN CubeSats on 11 January 2022, exclusively at sub‐MeV energy at L ∼ 8–10.5, where trapped MeV electrons were nearly absent. The THEMIS satellites observed conjugate H‐band and He‐band EMIC waves and hiss waves in plasmaspheric plumes near the magnetic equator. Quasi‐linear diffusion results demonstrate that the observed He‐band EMIC waves, with a high ratio of plasma to electron cyclotron frequency, can drive electron precipitation down to ∼400 keV. Our findings suggest that exclusive sub‐MeV precipitation (without concurrent MeV precipitation) can be associated with EMIC waves, especially in the plume region at high L shells.