Effects of Nearly Frontal and Highly Inclined Interplanetary Shocks on High‐Latitude Field‐Aligned Currents (FACs)
Effects of Nearly Frontal and Highly Inclined Interplanetary Shocks on High‐Latitude Field‐Aligned Currents (FACs)
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DOI：
10.1029/2019sw002367
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发表时间：
2019-12
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影响因子：
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通讯作者：
Yining Shi;D. Oliveira;D. Knipp;E. Zesta;T. Matsuo;B. Anderson
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作者：
Yining Shi;D. Oliveira;D. Knipp;E. Zesta;T. Matsuo;B. Anderson
通过叠加历元分析，我们给出了高纬度场向电流（FAC）对近锋地震（NFS）和高倾斜地震（HIS）的响应。FACs来自主动磁层和行星电动力学响应实验计划提供的磁扰动数据。每组49个事件用于叠加历元分析。研究了FAC和总电流分布的25%、50%和75%分位数。结果表明，在50%分位数范围内，NFS与HIS相比，前者的总电流都有较大幅度的增加，但前者的FAC增加幅度更大，FAC强度更强.在50%和75%分位数处，NFS在冲击到达后的第一个小时内触发的极光区电流扰动比HIS更强。在空间上，FAC响应的差异在（1）昼侧中午区，（2）黄昏区2电流系统，和（3）黎明侧中午前区1电流系统中最显著。我们的结果与以前的数值模拟结果一致，后者显示了高速和近正面冲击对磁层的更对称和更强的压缩。我们观测证实的作用，冲击波的影响角在控制后续的快速冲击的地震地球有效性。我们断言，通过上游太阳风模型确定冲击的影响角度可以提供有用的洞察力，在预测的地球有效性的冲击之前，它的到达磁层顶。
We present high‐latitude field‐aligned current (FAC) response to nearly frontal shocks (NFSs) and highly inclined shocks (HISs) through a superposed epoch analysis. The FACs are derived from magnetic perturbation data provided by the Active Magnetosphere and Planetary Electrodynamics Response Experiment program. Forty‐nine events for each group are used for the superposed epoch analysis. The 25%, 50%, and 75% quantiles of the FAC and total current distributions are studied. We found that NFSs are statistically stronger shocks in terms of solar wind parameters such as solar wind speed and interplanetary magnetic field.For the 50% quantiles, both groups of shocks produce rapid increases in total currents after shock arrival, but NFSs result in sharper increase in FACs and more intense FACs compared to HISs. At the 50% and 75% quantiles, NFSs trigger stronger auroral‐zone current disturbance for the first hour after shock arrival than do HISs. Spatially, the difference in FAC response is most notable in (1) the dayside noon region, (2) the duskside Region 2 current system, and (3) the dawnside prenoon Region 1 current system. Our results are consistent with previous numerical simulations that showed more symmetric and stronger compression of the magnetosphere for high‐speed and nearly frontal shocks. We observationally confirm the role of shock impact angle in controlling the subsequent shock geoeffectiveness for fast shocks. We assert that determining the shock impact angle via an upstream solar wind model could provide useful insight in forecasting the geoeffectiveness of a shock prior to its arrival at the magnetopause.