Modulation of chorus intensity by ULF waves deep in the inner magnetosphere

Zhiyang Xia; Lunjin Chen; Lei Dai; Seth G. Claudepierre; Anthony A. Chan; Angel Soto Chavez; G. D. Reeves

doi:10.1002/2016GL070280

Modulation of chorus intensity by ULF waves deep in the inner magnetosphere

Zhiyang Xia, Lunjin Chen, Lei Dai, Seth G. Claudepierre, Anthony A. Chan, Angel Soto Chavez, G. D. Reeves

Center For Solar Terrestrial Research - Big Bear Solar Observatory

Research output: Contribution to journal › Article › peer-review

37 Scopus citations

Abstract

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 <∼ 0.3f_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.

Original language	English (US)
Pages (from-to)	9444-9452
Number of pages	9
Journal	Geophysical Research Letters
Volume	43
Issue number	18
DOIs	https://doi.org/10.1002/2016GL070280
State	Published - Sep 28 2016

All Science Journal Classification (ASJC) codes

Geophysics
General Earth and Planetary Sciences

Keywords

ULF wave
chorus modulation
inner magnetosphere
whistler wave

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10.1002/2016GL070280

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title = "Modulation of chorus intensity by ULF waves deep in the inner magnetosphere",

abstract = "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 <∼ 0.3fce), 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.",

keywords = "ULF wave, chorus modulation, inner magnetosphere, whistler wave",

author = "Zhiyang Xia and Lunjin Chen and Lei Dai and Claudepierre, {Seth G.} and Chan, {Anthony A.} and {Soto Chavez}, Angel and Reeves, {G. D.}",

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doi = "10.1002/2016GL070280",

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T1 - Modulation of chorus intensity by ULF waves deep in the inner magnetosphere

AU - Xia, Zhiyang

AU - Chen, Lunjin

AU - Dai, Lei

AU - Claudepierre, Seth G.

AU - Chan, Anthony A.

AU - Soto Chavez, Angel

AU - Reeves, G. D.

PY - 2016/9/28

Y1 - 2016/9/28

N2 - 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 <∼ 0.3fce), 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.

AB - 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 <∼ 0.3fce), 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.

KW - ULF wave

KW - chorus modulation

KW - inner magnetosphere

KW - whistler wave

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Modulation of chorus intensity by ULF waves deep in the inner magnetosphere

Abstract

All Science Journal Classification (ASJC) codes

Keywords

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