ARTEMIS Observations of Foreshock Transients in the Midtail Foreshock
ARTEMIS Observations of Foreshock Transients in the Midtail Foreshock
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DOI：
10.1029/2020gl090393
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发表时间：
2020-11
影响因子：
5.2
通讯作者：
T. Liu;Chih‐Ping Wang;Boyi Wang;Xueyi Wang;Hui Zhang;Yu Lin;V. Angelopoulos
中科院分区：
文献类型：
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作者：
T. Liu;Chih‐Ping Wang;Boyi Wang;Xueyi Wang;Hui Zhang;Yu Lin;V. Angelopoulos
在日侧前震中经常观察到热流异常等前震瞬变现象。它们可以通过动态压力扰动干扰局部弓形激波、磁层顶，从而干扰磁层-电离层系统。最近的多点观测发现，这种扰动甚至可以从日面传播到中尾。然而，这种扰动的驱动因素，前震瞬态，是否在中尾前震中持续存在，尚未被观察到。因此，尚不清楚观测到的夜侧磁鞘/磁层顶扰动是行波还是由传播的前震瞬态连续驱动。利用两个月球与太阳相互作用的加速、重联、湍流和电动力学（ARTEMIS）航天器，我们报告了中尾前震瞬变的直接观测证据。我们提出了一个案例研究，显示了一个细长的成熟HFA以其驱动不连续从TH‐C （X ~−43 RE）传播到TH‐B （X ~−48 RE）。我们的结果证实，前激波瞬变在向尾传播时不仅干扰昼侧弓形激波，也干扰夜侧弓形激波。
Foreshock transients such as hot flow anomalies (HFAs) are frequently observed in the dayside foreshock. They can disturb the local bow shock, magnetopause, and consequently the magnetosphere‐ionosphere system through dynamic pressure perturbations. Recent multipoint observations found that such perturbations can even propagate from the dayside to the midtail. However, whether the drivers of such perturbations, foreshock transients, persist in the midtail foreshock has not been observed. Thus, it is unclear whether the observed nightside magnetosheath/magnetopause perturbations are traveling waves or continuously driven by a propagating foreshock transient. Using two Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) spacecraft, we report direct observational evidence of foreshock transients in the midtail foreshock. We present a case study showing an elongated mature HFA propagating with its driver discontinuity from TH‐C (X ~ −43 RE) to TH‐B (X ~ −48 RE). Our results confirm that foreshock transients disturb not only the dayside bow shock but also the nightside bow shock while propagating tailward.