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

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)9444-9452
Number of pages9
JournalGeophysical Research Letters
Issue number18
StatePublished - Sep 28 2016

All Science Journal Classification (ASJC) codes

  • Geophysics
  • General Earth and Planetary Sciences


  • ULF wave
  • chorus modulation
  • inner magnetosphere
  • whistler wave


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