Properties of Whistler Mode Waves in Earth's Plasmasphere and Plumes
Properties of Whistler Mode Waves in Earth's Plasmasphere and Plumes
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DOI：
10.1029/2018ja026041
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发表时间：
2019-02
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影响因子：
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通讯作者：
R. Shi;Wen Li;Q. Ma;Alex Green;C. Kletzing;W. Kurth;G. Hospodarsky;S. Claudepierre;H. Spence;G. Reeves
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文献类型：
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作者：
R. Shi;Wen Li;Q. Ma;Alex Green;C. Kletzing;W. Kurth;G. Hospodarsky;S. Claudepierre;H. Spence;G. Reeves
利用范艾伦探测器的5年数据，系统地研究了等离子层和羽流内部的惠斯勒模式波特性。等离子体层和羽流中哨声模式波的出现和强度与磁地方时、L和声发射有关。根据波法向角和坡印亭通量方向对L壳层的依赖关系以及归一化波频率对电子回旋频率的依赖关系，将哨声模波分为四种类型。I型：~0.5 fce，斜波法向角多为羽状；II型：0.01-0.5 fce，在外层等离子层或内部羽流中具有小波法向角；III型：<0.01 fce，斜波法向角主要在等离子体层或羽流内；IV型：0.05-0.5英尺，斜波法向角在等离子体层深处。I型和II型波的坡印亭通量主要远离赤道，表明局部放大，而III型和IV型波的坡印亭通量要么远离赤道，要么朝向赤道，可能来自其他源区。羽流中的惠斯勒模式波具有相对较小的波法向角，波印亭通量主要指向远离赤道的方向，并且与高电子通量相关，从~30 keV到数百keV，所有这些都支持局部放大。羽流中的哨声模式波振幅可能比典型的等离子体嘶嘶声更强，特别是在活动时期。我们的结果为理解等离子层和羽流内部的哨声模式波产生提供了关键的见解。
Whistler mode wave properties inside the plasmasphere and plumes are systematically investigated using 5‐year data from Van Allen Probes. The occurrence and intensity of whistler mode waves in the plasmasphere and plumes exhibit dependences on magnetic local time, L, and AE. Based on the dependence of the wave normal angle and Poynting flux direction on L shell and normalized wave frequency to electron cyclotron frequency (fce), whistler mode waves are categorized into four types. Type I: ~0.5 fce with oblique wave normal angles mostly in plumes; Type II: 0.01–0.5 fce with small wave normal angles in the outer plasmasphere or inside plumes; Type III: <0.01 fce with oblique wave normal angles mostly within the plasmasphere or plumes; Type IV: 0.05–0.5 fce with oblique wave normal angles deep inside the plasmasphere. The Poynting fluxes of Type I and II waves are mostly directed away from the equator, suggesting local amplification, whereas the Poynting fluxes of Type III and IV are directed either away from or toward the equator, and may originate from other source regions. Whistler mode waves in plumes have relatively small wave normal angles with Poynting flux mostly directed away from the equator and are associated with high electron fluxes from ~30 keV to hundreds of keV, all of which support local amplification. Whistler mode wave amplitudes in plumes can be stronger than typical plasmaspheric hiss, particularly during active times. Our results provide critical insights into understanding whistler mode wave generation inside the plasmasphere and plumes.