The study of bulk plasma motions and associated electric fields in the plasmasphere by means of whistler-mode signals
The study of bulk plasma motions and associated electric fields in the plasmasphere by means of whistler-mode signals
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DOI：
10.1016/s1364-6826(00)00217-0
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发表时间：
2001-07-01
影响因子：
1.9
通讯作者：
Smith, AJ
中科院分区：
文献类型：
--
作者：
Carpenter, DL;Smith, AJ
哨声模式波传播到地面站沿着地磁场对齐的路径提供了强有力的工具，调查块运动的磁层等离子体，从而相应的对流电场。自然哨声从闪电以及信号从甚低频（VLF）发射机已被采用。哨声方法强调测量频率随时间或色散的时间变化，哨声的属性，而发射机方法侧重于测量固定频率信号传播的相位和群路径。这些方法依赖于对地磁场的不均匀性敏感的波的性质，从而提供关于在与地球一起旋转的参考系中基本上是交叉L等离子体运动的信息。此外，哨声数据的duskside等离子体膨胀已被用来估计值的径向对流电场（GSE Y方向）近黄昏。在这篇专题评论中，我们讨论了从20世纪60年代开始的哨声和发射机方法的发展，以及它们的一些地球物理应用。哨声提供了大量的新信息的空间和时间结构的方式，对流电场穿透等离子体-一个例子是仍然无法解释的逆转从内向外的午夜后径向如何方向以下暂时孤立的亚暴。哨声还有助于识别与电离层发电机起源的静日电场相关的等离子体层漂移，并表明外等离子体层对流电场的E-y（向黄昏）分量在黄昏时比在午夜时大得多。哨声模式的信号从发射机已被发现是一个强大的手段，在L = 2.5附近的等离子体轨道跟踪跨L运动，同时分别确定交换通量与电离层上的信号相位和组路径的影响。(C)2001爱思唯尔科技有限公司版权所有。
Whistler-mode waves propagating to ground stations along geomagnetic-field-aligned paths provide powerful tools for investigating bulk motions of the magnetospheric plasma and thus the corresponding convection electric fields. Natural whistlers from lightning as well as signals from very low frequency (VLF) transmitters have been employed. The whistler method emphasizes measurement of temporal variations in the frequency versus time- or dispersion, properties of whistlers, while the transmitter method focuses upon measurement of the phase and group paths of fixed-frequency signal propagation. The methods depend upon wave properties that are sensitive to inhomogeneities in the geomagnetic field, and thus provide information on what are essentially cross-L plasma motions in a frame of reference rotating with the Earth. In addition, whistler data on the duskside plasmasphere bulge have been used to estimate values of the radial convection electric field (GSE Y direction) near dusk. In this topical review we discuss the development, beginning in the 1960s, of the whistler and transmitter methods, as well as a few of their geophysical applications. Whistlers have provided substantial new information on the spatially and temporally structured manner in which convection electric fields penetrate the plasmasphere- one example being the still unexplained reversal from inward to outward of the post-midnight radial how direction following temporally isolated substorms. Whistlers have also been useful in identifying the plasmaspheric drifts associated with quiet-day electric fields of ionospheric dynamo origin and in showing that the E-y (duskward), component of the convection electric field in the outer plasmasphere is substantially larger near dusk than it is near mid-night. Whistler-mode signals from transmitters have been found to be a powerful means of tracking cross-L motions in the plasmasphere near L = 2.5 while separately identifying the effects of interchange fluxes with the ionosphere on the signal phase and group paths. (C) 2001 Elsevier Science Ltd. All rights reserved.