Modulation of plasmaspheric hiss intensity by thermal plasma density structure

被引：47
作者：
Chen, Lunjin [1 ]
Thorne, Richard M. [1 ]
Li, Wen [1 ]
Bortnik, Jacob [1 ]
Turner, Drew [2 ,3 ]
Angelopoulos, Vassilis [2 ,3 ]
机构：
[1] Univ Calif Los Angeles, Dept Atmospher & Ocean Sci, Los Angeles, CA 90024 USA
[2] Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA
[3] Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA
来源：
GEOPHYSICAL RESEARCH LETTERS | 2012年 / 39卷
基金：
美国国家科学基金会;
关键词：
DISCRETE CHORUS EMISSIONS; RADIATION BELT ELECTRONS; ORIGIN; THEMIS; MAGNETOSPHERE; INSTRUMENT;
D O I：
10.1029/2012GL052308
中图分类号：
P [天文学、地球科学];
学科分类号：
07 ;
摘要：
Plasmaspheric hiss is an electromagnetic whistler-mode emission confined to high density regions such as the plasmasphere and plasmaspheric plumes. We present a dayside THEMIS event showing that the hiss emission intensity is strongly modulated by thermal plasma density variations. The calculated local growth rate is small (less than 5 dB/R-E) and increases as the plasma density increases, which partly accounts for the modulation. Ray tracing shows that chorus rays, which eventually evolve into plasmaspheric hiss, are focused towards field lines of higher density and defocused away from field lines of lower density. We suggest that the observed modulation is caused by a combined effect of local cyclotron resonant amplification together with ray focusing during propagation.
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页数：6
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