On the influence of open magnetic flux on substorm intensity: Ground‐ and space‐based observations
On the influence of open magnetic flux on substorm intensity: Ground‐ and space‐based observations
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开放磁通量对亚暴强度的影响：地基和空基观测
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
B. Anderson
中科院分区：
文献类型：
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作者：
L. Clausen;S. Milan;J. Baker;J. Ruohoniemi;K. Glassmeier;J. Coxon;B. Anderson
利用活动磁层和行星电动力学响应实验确定的最大1区电流位置作为开/闭场线边界的代理，我们监测了772次亚暴期间磁层内开放磁通量的变化。然后，根据膨胀阶段开始时开放通量的大小，我们将所有亚暴分为三类。研究了各类亚暴期间若干相关地球物理参数的时间变化，发现在开放通量较大时发生的亚暴通常更为强烈。我们所说的强是指极光电喷流、1区电流、极光亮度、尾双极化和流速、地磁特征、Pi2波功率以及亚暴电流楔（SCW）的强度和范围都大于收缩极帽上发生的亚暴。SCW表现为发生后夜侧R1和R2电流系统的增强。我们的分析表明，为了处理大量积累的开放磁通量，在地球磁层中触发了大的亚暴。
Using the location of maximum region 1 current determined by the Active Magnetosphere and Planetary Electrodynamics Response Experiment as a proxy for the open/closed field line boundary, we monitor the evolution of the amount of open magnetic flux inside the magnetosphere during 772 substorms. We then divide all substorms into three classes, depending on the amount of open flux at expansion phase onset. Studying the temporal variations during the substorms of each class for a number of related geophysical parameters, we find that substorms occurring while the amount of open flux is large are generally more intense. By intense we mean that the auroral electrojet, region 1 current, auroral brightness, tail dipolarization and flow speed, ground magnetic signatures, Pi2 wave power, as well as the intensity and extent of the substorm current wedge (SCW) are all larger than during substorms that occur on a contracted polar cap. The SCW manifests itself as an intensification of the nightside R1 and R2 current system after onset. Our analysis shows that to dispose of large amounts of accumulated open magnetic flux, large substorms are triggered in the terrestrial magnetosphere.