Substorm timings and timescales: A new aspect
Substorm timings and timescales: A new aspect
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DOI：
10.1023/b:spac.0000042939.88548.68
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发表时间：
2004-10
影响因子：
10.3
通讯作者：
C. Meng;K. Liou
中科院分区：
文献类型：
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作者：
C. Meng;K. Liou
磁层亚暴是磁层扰动的基本要素。经过40多年的深入研究，亚暴形态的各个方面已经定性确立。国际日地物理飞行任务在过去十年中的观测提供了比以前更详细、更完整的亚暴图像，因此，为亚暴机制提供了新的见解。从全球极光图像可以看出，亚暴的起始点是局部受限的；然而，在不同的时间，亚暴的影响涉及到非常大的空间。依赖情景技术的观察可能会产生误导，如果没有正确解释，可能会带来混乱。另一方面，全球极光成像等遥感技术不仅为研究亚暴现象提供了强有力的手段，而且还产生了相对一致的结果。本文回顾和总结了主要根据美国国家航空航天局极光卫星的全球极光图像进行的一些亚暴研究，主要侧重于“定量”亚暴形态(即开始时间、地点、能量输入和亚暴时间尺度)。这些研究得出的结论是：(1)极光破裂是最可靠的亚暴指标，而其他常用的爆发指标可能并不总是与亚暴有关，并受到传播延迟的影响；(2)极光破裂后，扩展的极光隆起可以向西移动(60%)或向东移动(40%)；(3)典型的亚暴扩张阶段持续∼10分钟，并随着距离爆发的增加而增加。最近一些研究得出的一个关键结论似乎表明，磁尾重联即使存在，也是亚暴扩张开始的结果。这些发现为亚暴模型和理论提供了约束。
The magnetospheric substorm is a fundamental element of magnetospheric disturbances. After more than 40 years of intensive studies, various aspects of substorm morphology have been qualitatively established. Observations from the International Solar-Terrestrial Physics (ISTP) mission during the last decade have provided more detailed and complete pictures of substorms than before and, consequently, have provided new insights into substorm mechanisms. From the global auroral imaging it is shown that substorm onsets are locally confined; however, the effects of substorms involve a very large space at different times. Observations relying onin situtechniques can be misleading and can introduce confusion if not properly interpreted. On the other hand, remote sensing techniques such as global auroral imaging not only provide a robust means for studying substorm phenomenology but also yield relatively consistent results. This article reviews and summarizes a number of substorm studies conducted based primarily on global auroral images from NASA's Polar satellite, with a main focus on “quantitative” substorm morphology (i.e., onset timing, locations, energy input, and substorm timescales). These studies conclude that (1) auroral breakups are the most reliable substorm indicator, whereas other commonly used onset proxies may not always be associated with substorms and are subject to a propagation delay; (2) after breakup, the expanded auroral bulge can move either westward (60%) or eastward (40%); and (3) a typical substorm expansion phase lasts ∼10 minutes and increases with increasing distances from the onset. A key conclusion from some recent studies seems to suggest that magnetotail reconnection, if it ever exists, is a consequence of substorm expansion onset. These findings provide constraints for substorm models and theories.