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Correlated Observation on Global Distributions of Magnetosonic Waves and Proton Rings in the Radiation Belts
Author(s) -
Zhou Qinghua,
Jiang Zheng,
Yang Chang,
He Yihua,
Liu Si,
Xiao Fuliang
Publication year - 2021
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2020ja028354
Subject(s) - physics , proton , ring current , excited state , earth's magnetic field , van allen probes , van allen radiation belt , ring (chemistry) , astrophysics , atomic physics , computational physics , nuclear physics , magnetic field , magnetosphere , plasma , chemistry , quantum mechanics , organic chemistry
Abstract Fast magnetosonic (MS) waves are excited by the ring distribution of energetic protons preferably when the ring velocity ( V R ) is within a factor of 2 above or below the local Alfvén speed ( V A ). Here we examine the global distributions of MS waves and proton rings with 0.5 V A ≤ V R ≤ 2 V A based on 64 months (from October 25, 2012 to February 28, 2018) of Van Allen Probes observations. The statistical results show that MS waves are present over a broad region of L = 1.2–6.0 and 00–24 magnetic local time (MLT), with a higher occurrence rate at L = 2.5–5.5 on the dayside. Proton rings occur mainly on the dayside of L > 5.0. During active geomagnetic periods, both MS waves and proton rings occur more frequently and extend to low L ‐shells. The current results provide the further observational evidence that MS waves can be excited by proton rings at a distant region and propagate to low L ‐shells.