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Modeling the Electron Flux Enhancement and Butterfly Pitch Angle Distributions on L Shells <2.5
Author(s) -
Hua Man,
Li Wen,
Ma Qianli,
Ni Binbin,
Nishimura Yukitoshi,
Shen XiaoChen,
Li Haimeng
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl084822
Subject(s) - van allen radiation belt , pitch angle , physics , electron , van allen probes , flux (metallurgy) , geomagnetic storm , butterfly , hiss , diffusion , scattering , computational physics , radiation , electron scattering , earth's magnetic field , atomic physics , magnetosphere , geophysics , magnetic field , plasma , optics , nuclear physics , materials science , finance , quantum mechanics , economics , metallurgy , thermodynamics
We analyze an energetic electron flux enhancement event in the inner radiation belt observed by Van Allen Probes during an intense geomagnetic storm. The energetic electron flux at L~1.5 increased by a factor of 3 with pronounced butterfly pitch angle distributions (PADs). Using a three‐dimensional radiation belt model, we simulate the electron evolution under the impact of radial diffusion, local wave‐particle interactions including hiss, very low frequency transmitters, and magnetosonic waves, as well as Coulomb scattering. Consistency between observation and simulation suggests that inward radial diffusion plays a dominant role in accelerating electrons up to 900 keV and transporting the butterfly PADs from higher L shells to form the butterfly PADs at L~1.5. However, local wave‐particle interactions also contribute to drive butterfly PADs at L ≳ 1.9. Our study provides a feasible mechanism to explain the electron flux enhancement in the inner belt and the persistent presence of the butterfly PADs at L~1.5.