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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >Substorm cycle dependence of various types of aurora
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Substorm cycle dependence of various types of aurora

机译：各种类型的亚暴循环依赖极光

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摘要

We combine 4861 identifications of substorm onsets from satellite global imagers (Polar UVI and IMAGE FUV) with DMSP particle data to investigate the substorm cycle dependence of the diffuse aurora (electrons and ions), monoenergetic aurora (produced by quasi-static electric fields), and broadband aurora (associated with Alfvenic acceleration). Although all types of aurora increase at substorm onset, broadband aurora shows a particular association with substorms and, especially, substorm onset. While diffuse electron and monoenergetic auroral precipitating power rises by 79% and 90%, respectively, following an onset, wave aurora rises by 182%. In the first 10-15 min following onset, the power associated with Alfvenic acceleration is comparable to monoenergetic acceleration (also called "inverted V" events). In general, this is not the case before onset, or indeed, during recovery. The rise time of the electron diffuse aurora following onset is much slower, about 50 min, and thus presumably extends into recovery. Discrete acceleration, which rises over just a few minutes, is already deep into decline, while diffuse auroral power is still rising. Most of the sharp increase in Alfvenic precipitating power at onset is associated with a 132% jump in the characteristic energy associated with broadband acceleration. Previous work has associated PiB signatures (which are compressional) in the magnetotail with dipolarization. More recently, FAST observations near the auroral zone have been used to show that there are nearly simultaneous sharp increases in Alfven waves, apparently created by mode coupling. The present work strongly supports the idea that the Alfvenic aurora has a particular connection to substorm onsets, with much of the auroral power over a substorm cycle concentrated shortly after onset. Finally, a superposed epoch analysis of commonly used coupling functions indicates a drop in the mean solar wind driving starting 20 min before substorm onset. However, the distribution of increases and decreases in solar wind driving is roughly symmetric about a peak at zero (no change) but with (rare) large drops in solar wind driving ("northward turnings") outweighing large increases. Comparison with the distribution of random changes in solar wind driving leads us to suggest that probably only a minority of substorms are externally driven.
机译：我们把4861识别亚暴发作从全球卫星成像系统(极紫外线指数和图像FUV)与粒子DMSP数据进行调查分散的亚暴循环依赖极光(电子和离子),单色的极光(由准静态电场),宽带极光(与Alfvenic有关加速度)。在亚暴开始增加,宽带极光展示了一个特定的协会,与亚暴发病,特别是亚暴。电子和单色的极光沉淀权力上升了79%和90%,分别发病后,波极光上升了182%。第一个10 - 15分钟后开始,力量与Alfvenic加速度有关与单色的加速度(也称为“倒V”事件)。不是这样的在发病之前,或事实上,期间复苏。极光出现后要慢得多,大约50最小值,因此可能延伸到经济复苏。只是一个离散加速度,它上升几分钟,已经深入下滑,而扩散极光权力仍在上升。大幅增加Alfvenic沉淀权力在发病与增长了132%能源相关的特征宽带加速度。加以签名(有关压缩)在磁尾dipolarization。极光区附近的人都被用来显示有几乎同时大幅增加阿尔芬波,显然是由模式耦合。认为Alfvenic极光有特定的连接亚暴发作的极光亚暴周期权力集中开始后不久。常用的耦合分析功能表明下降的意思是太阳风开车开始亚暴开始前20分钟。增加和减少的分布太阳风开车大概是对称的峰值为零(没有变化),但(罕见)滴在太阳风驾驶(“向北切屑”)超过大量增加。与随机的分布进行比较太阳风的变化使我们建议开车可能只有少数亚暴外部驱动的。

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