Distinction between auroral substorm onset and traditional ground magnetic onset signatures
Distinction between auroral substorm onset and traditional ground magnetic onset signatures
复制标题
极光亚暴爆发与传统地磁爆发特征之间的区别
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
V. Angelopoulos
中科院分区：
文献类型：
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作者：
L. Lyons;Y. Nishimura;E. Donovan;V. Angelopoulos
为了评估传统上被视为亚暴爆发特征的地面磁响应是否可能与震后极光流光有关，而不是与极光中看到的亚暴爆发有关，我们分析了仅根据成像仪覆盖范围选择的 14 个亚暴爆发的地面磁响应和全天图像响应。我们发现证据支持这种可能性，中纬度正湾和 Pi2 脉动增强的响应与流光附近站的极光区 H 突然减小的响应大致一致。这些都是电流楔形成的特征，表明亚暴电流楔的形成可能更多地是对与震后流光相关的等离子体片流通道的响应，而不是对导致极光爆发的过程的响应，并且电流楔可能通过一系列明显更窄的楔状结构发展。我们还发现证据表明，在亚暴扩展阶段，流光周期可能会出现多次，并且即使没有额外的极光爆发，也可以给出多次爆发的磁特征。此外，峰值极光区 H 的下降与流光有关，如果流光持续时间较长，则有时会在亚暴极光出现后几分钟到半小时以上不等。这表明峰值亚暴 AE 和 AL 值可能与震后流光的特征及其相对于观测站的位置有关，而不是亚暴极光爆发过程强度的衡量标准。我们讨论对亚暴扩展阶段发展可能产生的其他影响。
To evaluate whether ground magnetic responses traditionally viewed as signatures of substorm onset may be related to postonset auroral streamers rather than to substorm onset seen in aurora, we have analyzed ground magnetic and all‐sky image responses for 14 substorm onsets selected solely on imager coverage. We find evidence supporting this possibility, the response being approximately coincident for midlatitude positive bay and Pi2 pulsation enhancements and for abrupt auroral zone H decreases at stations near a streamer. These are all signatures of current wedge formation, indicating that substorm current wedge formation may be more of a response to plasma sheet flow channels associated with postonset streamers than to the process leading to auroral onset and that the current wedge may develop via a series of distinctly narrower wedge‐like structures. We also find evidence that periods of streamers can occur more than once during a substorm expansion phase and can give magnetic signatures of multiple onsets even if there are no additional auroral onsets. Furthermore, the peak auroral zone H decreases are seen in association with streamers and at times varying from just a few minutes to well over a half hour after substorm auroral onset if there is a prolonged period of streamers. This indicates that peak substorm AE and AL values are likely related to features of postonset streamers and their locations relative to observing stations and are not a measure of the strength of the substorm auroral onset processes. We discuss possible additional implications on substorm expansion phase development.
影响因子：
5.2
作者：
Donovan, E.;Liu, W.;Rae, I. J.
通讯作者：
Rae, I. J.