Diagnosing the Time‐Dependent Nature of Magnetosphere‐Ionosphere Coupling via ULF Waves at Substorm Onset
Diagnosing the Time‐Dependent Nature of Magnetosphere‐Ionosphere Coupling via ULF Waves at Substorm Onset
复制标题
通过亚暴爆发时的 ULF 波诊断磁层-电离层耦合的时间依赖性
DOI：
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
I. Mann
中科院分区：
文献类型：
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作者：
A. Smith;I. J. Rae;C. Forsyth;C. Watt;K. Murphy;I. Mann
方位向结构通常是在明亮的极光亚暴起始弧内观察到的；这种结构与电磁超低频(ULF)波的指数增长有关。我们提供了一个研究这种超低频波在地面和近地磁尾的时间和频率依赖性的案例研究。在磁尾，我们观察到在10到100 S周期范围内宽带波功率的增加。在地面上，到达时间从震中蔓延开来。较长周期的波首先出现，并且在纬度和经度上传播最快，而较短的周期似乎更局限于起始弧线。推算出从航天器到地面的旅行时间，对于15-60 S的超低频波周期，大约为1-2 分钟；对于较长周期的波，穿越时间为60 S或更短。这种差异可能归因于较短周期波的优先衰减，因为它们的幅度需要更长的时间才能上升到背景水平以上。这些结果对限制近地磁尾亚暴爆发过程的物理过程及其与地面的通信具有重要的影响。
Azimuthal structuring is usually observed within the brightening auroral substorm onset arc; such structure has been linked to the exponential growth of electromagnetic ultralow‐frequency (ULF) waves. We present a case study investigating the timing and frequency dependence of such ULF waves on the ground and in the near‐Earth magnetotail. In the magnetotail, we observe an increase in broadband wave power across the 10‐ to 100‐s period range. On the ground, the arrival times spread from an epicenter. The onset of longer period waves occurs first and propagates fastest in latitude and longitude, while shorter periods appear to be more confined to the onset arc. The travel time from the spacecraft to the ground is inferred to be approximately 1–2 min for ULF wave periods between 15 and 60 s, with transit times of 60 s or less for longer period waves. This difference might be attributed to preferential damping of the shorter period waves, as their amplitude would take longer to rise above background levels. These results have important consequences for constraining the physics of substorm onset processes in the near‐Earth magnetotail and their communication to the ground.
DOI：
10.1002/2015ja021343
发表时间：
2015-12
期刊：
Journal of Geophysical Research: Space Physics
影响因子：
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作者：
C. Forsyth;I. J. Rae;J. Coxon;M. Freeman;C. Jackman;Jesper Gjerloev;Jesper Gjerloev;A. Fazakerley
通讯作者：
C. Forsyth;I. J. Rae;J. Coxon;M. Freeman;C. Jackman;Jesper Gjerloev;Jesper Gjerloev;A. Fazakerley
影响因子：
5.2
作者：
Donovan, E.;Liu, W.;Rae, I. J.
通讯作者：
Rae, I. J.