Poleward‐moving auroral form (PMAF) is a type of dayside auroral pattern. The distinguishing characteristic of a PMAF is its separation from the auroral oval and subsequent poleward motion. It has been reported and widely accepted that PMAFs occur more frequently during periods with dominant southward interplanetary magnetic field (IMF). However, most ground‐based optical observations were made near magnetic latitudes of 75°, close to the equatorward boundary of the dayside auroral oval; therefore, PMAFs occurring at the poleward boundary were likely missed easily. Using all‐sky images from two stations located on the similar magnetic meridian in Antarctica at 80° and 75° magnetic latitude, and taking solar wind data close to the magnetosphere by the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft, we demonstrate that unlike the result from prior low‐latitude single‐station observations, the combined observations from both stations show an insignificant difference in the PMAF occurrence rate in the northward and southward IMF conditions and no clear sign suggesting that the southward IMF or southward turning of the IMF triggers PMAFs. With good agreements between PMAF occurrence rate and the intensity of the poleward drift, we suggest that PMAFs are more likely to be plasma patches torn away from the dayside auroral oval convecting antisunward and rather than direct foot points of reconnecting flux tubes.

中文翻译：

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对南极极光椭圆的赤道和极向边界极移动的极光形式的同时观测

极移型极光形式（PMAF）是一种日间极光模式。PMAF的显着特征是其与极光椭圆的分离以及随后的极向运动。据报道并被广泛接受，PMAFs在占主导地位的向南行星际磁场（IMF）期间更频繁地发生。但是，大多数基于地面的光学观测是在75°的磁性纬度附近进行的，靠近日间极光椭圆的赤道边界。因此，极地边界处发生的PMAF很容易被错过。利用来自南极类似磁子午线的两个站点在80°和75°磁纬度上的全天影像，并通过亚暴期间事件和宏观尺度相互作用的时间历史记录和接近磁层的太阳风数据，我们证明，与之前的低纬度单站观测结果不同，两个站的组合观测结果显示，在北向和南向IMF条件下，PMAF发生率差异不明显，没有明显迹象表明南向IMF或向南转弯IMF触发PMAF。在PMAF发生率和极向漂移强度之间达成良好一致的情况下，我们建议PMAF更有可能是血浆碎片从远离对流的日间极光椭圆形撕裂而对流，而不是直接重新连接通量管的脚点。这两个站的综合观测结果显示，在北向和南向IMF条件下，PMAF发生率差异不明显，也没有明确迹象表明南向IMF或IMF向南翻转触发PMAF。在PMAF发生率和极向漂移强度之间达成良好一致的情况下，我们建议PMAF更有可能是血浆碎片从远离对流的日间极光椭圆形撕裂而对流，而不是直接重新连接通量管的脚点。这两个站的综合观测结果显示，在北向和南向IMF条件下，PMAF发生率差异不明显，也没有明确迹象表明南向IMF或IMF向南翻转触发PMAF。在PMAF发生率和极向漂移强度之间达成良好一致的情况下，我们建议PMAF更有可能是血浆碎片从远离对流的日间极光椭圆形撕裂而对流，而不是直接重新连接通量管的脚点。