A new technique for determining Substorm Onsets and Phases from Indices of the Electrojet (SOPHIE)
A new technique for determining Substorm Onsets and Phases from Indices of the Electrojet (SOPHIE)
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DOI：
10.1002/2015ja021343
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发表时间：
2015-12
期刊：
影响因子：
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通讯作者：
C. Forsyth;I. J. Rae;J. Coxon;M. Freeman;C. Jackman;Jesper Gjerloev;Jesper Gjerloev;A. Fazakerley
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文献类型：
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作者：
C. Forsyth;I. J. Rae;J. Coxon;M. Freeman;C. Jackman;Jesper Gjerloev;Jesper Gjerloev;A. Fazakerley
我们提出了一种新的定量技术，确定的时间和持续时间的亚暴扩展和恢复阶段和可能的增长阶段的基础上的极光电喷流指数的变化率的斜率。通过能够规定不同的百分位值，我们可以确定极光指数或任何极光区地面磁力计数据的较小或较大变化的亚暴阶段的开始和持续时间。我们将这种技术应用于SuperMAG AL（SML）指数，并将我们的膨胀阶段开始时间与以前的亚暴开始时间列表进行比较。我们发现，超过50%的事件在以前的列表中发生在20分钟内，我们确定的发病。我们还提出了一个叠加的历元分析的SML的基础上，我们的技术和现有的发作列表确定我们的发作的比较，并发现亚暴湾的一般特征是可比的。通过规定用户定义的阈值，这种自动化的定量技术代表了对亚暴发生的任何视觉识别或实际上任何固定阈值方法的改进。
We present a new quantitative technique that determines the times and durations of substorm expansion and recovery phases and possible growth phases based on percentiles of the rate of change of auroral electrojet indices. By being able to prescribe different percentile values, we can determine the onset and duration of substorm phases for smaller or larger variations of the auroral index or indeed any auroral zone ground‐based magnetometer data. We apply this technique to the SuperMAG AL (SML) index and compare our expansion phase onset times with previous lists of substorm onsets. We find that more than 50% of events in previous lists occur within 20 min of our identified onsets. We also present a comparison of superposed epoch analyses of SML based on our onsets identified by our technique and existing onset lists and find that the general characteristics of the substorm bay are comparable. By prescribing user‐defined thresholds, this automated, quantitative technique represents an improvement over any visual identification of substorm onsets or indeed any fixed threshold method.