共 46 条
Analyzing EMIC Waves in the Inner Magnetosphere Using Long-Term Van Allen Probes Observations
被引:30
作者:
Chen, Huayue
[1
]
Gao, Xinliang
[1
]
Lu, Quanming
[1
]
Wang, Shui
[1
]
机构:
[1] Univ Sci & Technol China, Sch Earth & Space Sci, CAS Key Lab Geosci Environm, Hefei, Anhui, Peoples R China
基金:
中国国家自然科学基金;
关键词:
EMIC wave;
inner magnetosphere;
Van Allen Probes observation;
a long-term statistical work;
spatial distribution;
wave fundamental characters;
ION-CYCLOTRON WAVES;
RELATIVISTIC ELECTRONS;
ENERGETIC PARTICLE;
O+;
H+;
POLARIZATION;
PULSATIONS;
SCATTERING;
D O I:
10.1029/2019JA026965
中图分类号:
P1 [天文学];
学科分类号:
0704 ;
摘要:
With 64-month magnetic data from Van Allen Probes, we have studied not only the global distribution, wave normal angle (theta), and ellipticity (epsilon) of electromagnetic ion cyclotron (EMIC) waves, but also the dependence of their occurrence rates and magnetic amplitudes on the AE* index (the mean value of AE index over previous 1 hr). Our results show that H+ band waves are preferentially detected at 5 <= L <= 6.5, in the noon sector. They typically have small theta () and weakly left-hand polarization but become more oblique and linearly polarized at larger magnetic latitudes or L-shells. With the increase of AE* index, their occurrence rate significantly increases in the noon sector, and their source region extends to dusk sector. He+ band waves usually occur in the predawn and morning sectors at 3 <= L <= 4.5. They generally have moderate theta (30 degrees - 40 degrees) and left-hand polarization and also become more oblique and linearly polarized at larger latitudes or L-shells. There is a clear enhancement of occurrence rate and amplitude during active geomagnetic periods, especially in the dusk and evening sectors. O+ band waves mainly occur at 3 <= L <= 4 in the predawn sector. They have either very small theta () or very large theta (>50 degrees), and typically linear or weakly right-hand polarization. During active periods, they mostly occur at the midnight sector and L . As a valuable supplement to previous statistical studies, our result provides not only a more compresentive EMIC wave model for evaluating their effects on the radiation belt, but also detailed observational constraints on generation mechanisms of EMIC waves.
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页码:7402 / 7412
页数:11
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