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Modulation of chorus intensity by ULF waves deep in the inner magnetosphere
Author(s) -
Xia Zhiyang,
Chen Lunjin,
Dai Lei,
Claudepierre Seth G.,
Chan Anthony A.,
SotoChavez A. R.,
Reeves G. D.
Publication year - 2016
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 - 10.1002/2016gl070280
Subject(s) - chorus , van allen probes , magnetosphere , physics , van allen radiation belt , intensity (physics) , computational physics , geophysics , optics , nuclear physics , plasma , art , literature
Previous studies have shown that chorus wave intensity can be modulated by Pc4‐Pc5 compressional ULF waves. In this study, we present Van Allen Probes observation of ULF wave modulating chorus wave intensity, which occurred deep in the magnetosphere. The ULF wave shows fundamental poloidal mode signature and mirror mode compressional nature. The observed ULF wave can modulate not only the chorus wave intensity but also the distribution of both protons and electrons. Linear growth rate analysis shows consistence with observed chorus intensity variation at low frequency ( f <∼ 0.3 f ce ), but cannot account for the observed higher‐frequency chorus waves, including the upper band chorus waves. This suggests the chorus waves at higher‐frequency ranges require nonlinear mechanisms. In addition, we use combined observations of Radiation Belt Storm Probes (RBSP) A and B to verify that the ULF wave event is spatially local and does not last long.