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A Statistical Test of the Relationship Between Chorus Wave Activation and Anisotropy of Electron Phase Space Density

A Statistical Test of the Relationship Between Chorus Wave Activation and Anisotropy of Electron Phase Space Density

Authors :
Dong-Hee Lee
Dae-Young Lee
Dae-Kyu Shin
Jin-Hee Kim
Jung-Hee Cho
Source :
Journal of Astronomy and Space Sciences, Vol 31, Iss 4, Pp 295-301 (2014)
Publication Year :
2014
Publisher :
The Korean Space Science Society, 2014.

Abstract

Whistler mode chorus wave is considered to play a critical role in accelerating and precipitating the electrons in the outer radiation belt. In this paper we test a conventional scenario of triggering chorus using THEMIS satellite observations of waves and particles. Specifically, we test if the chorus onset is consistent with development of anisotropy in the electron phase space density (PSD). After analyzing electron PSD for 73 chorus events, we find that, for ~80 % of them, their onsets are indeed associated with development of the positive anisotropy in PSD where the pitch angle distribution of electron velocity peaks at 90 degrees. This PSD anisotropy is prominent mainly at the electron energy range of ≤ ~20 keV. Interestingly, we further find that there is sometimes a time delay among energies in the increases of the anisotropy: A development of the positive anisotropy occurs earlier by several minutes for lower energy than for an adjacent higher energy.

Details

Language :
English
ISSN :
20935587 and 20931409
Volume :
31
Issue :
4
Database :
Directory of Open Access Journals
Journal :
Journal of Astronomy and Space Sciences
Publication Type :
Academic Journal
Accession number :
edsdoj.5f7562e1527d4b5abfa0aadcd15eaa1d
Document Type :
article
Full Text :
https://doi.org/10.5140/JASS.2014.31.4.295