The polar cap arc at 1500 MLT (15MLT-PCA) has been considered as an auroral signature of the cusp's duskside boundary and been speculated to be caused by lobe reconnection. However, no observational evidence has been provided to support this speculation. Here we report a 15MLT-PCA event occurred on 29 November 2017 using multi-instrument observations. During the DMSP observed the 15MLT-PCA, Cluster, with its footprints at the root of the 15MLT-PCA, identified two FTEs in the southern hemisphere's lobe region, accompanied by an increase in electron and ion energy from hundreds of eVs to several keVs. AMPERE observed an increase in upward field-aligned currents associated with the 15MLT-PCA. SuperDARN observed a single cell convection with an enhancement of sunward plasma flow near the root of 15MLT-PCA. We suggest that these observations provide the in-situ observational evidence that the 15MLT-PCA is generated by a lobe reconnection at the cusp's duskside boundary.

中文翻译：

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1500 MLT （15MLT-PCA） 极帽弧与叶重连接相关的原位观测证据


1500 MLT （15MLT-PCA） 的极帽弧被认为是尖头黄昏侧边界的极光特征，并被推测是由叶重新连接引起的。然而，没有提供任何观测证据来支持这一推测。在这里，我们使用多仪器观测报告了 2017 年 11 月 29 日发生的 15MLT-PCA 事件。在 DMSP 观测 15MLT-PCA 期间，星团的足迹位于 15MLT-PCA 的根部，在南半球的叶区发现了两个 FTE，伴随着电子和离子能量从数百 eV 增加到几 keV。AMPERE 观察到与 15MLT-PCA 相关的向上磁场对准电流增加。SuperDARN 观察到单细胞对流，在 15MLT-PCA 根部附近向阳血浆流增强。我们认为这些观察提供了原位观测证据，证明 15MLT-PCA 是由尖头黄昏边界的叶重新连接产生的。