The terrestrial magnetosphere is perpetually exposed to and significantly deformed by the interplanetary magnetic field (IMF) in the solar wind. This deformation is typically detected at discrete locations by space‐ and ground‐based observations. Earth's aurora, on the other hand, is a globally distributed phenomenon that may be used to elucidate magnetospheric deformations caused by IMF variations, as well as plasma supply from the deformed magnetotail to the high‐latitude atmosphere. We report the utilization of an auroral form known as the transpolar arc (TPA) to diagnose the plasma dynamics of the globally deformed magnetosphere. Nine TPAs examined in this study have two types of a newly identified morphology, which are designated as “J”‐ and “L”‐shaped TPAs from their shapes and are shown to have antisymmetric morphologies in the Northern Hemisphere and Southern Hemisphere, depending on the IMF polarity. The TPA‐associated ionospheric current profiles suggest that electric currents flowing along the magnetic field lines (field‐aligned currents [FACs]), connecting the magnetotail and the ionosphere, may be related to the “J”‐ and “L”‐shaped TPA formations. The FACs can be generated by velocity shear between fast plasma flows associated with nightside magnetic reconnection and slower background magnetotail plasma flows. Complex large‐scale TPA FAC structures, previously unraveled by an magnetohydrodynamic (MHD) simulation, cannot be elucidated by our observations. However, our interpretation of TPA features in a global context facilitates the usage of TPA as a diagnostic tool to effectively remote sense globally deformed terrestrial and planetary magnetospheric processes in response to the IMF and solar wind plasma conditions.

中文翻译：

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变形的磁层-电离层耦合框架内的南北非对称夜场畸变的跨极弧：IMF-依赖，电离层电流和磁尾重连

地球磁层永久暴露于太阳风中的行星际磁场（IMF）并严重变形。通常通过基于空间和地面的观测在离散位置检测到这种变形。另一方面，地球的极光是一种全球分布的现象，可用于阐明由IMF变化引起的磁层变形以及从变形的磁尾到高纬度大气的等离子体供应。我们报告利用称为跨极电弧（TPA）的极光形式来诊断全球变形磁层的等离子体动力学。在这项研究中检查的9种TPA具有两种新近识别出的形态，它们的形状被称为“ J”形和“ L”形TPA，并且在北半球和南半球显示出具有反对称的形态，具体取决于IMF极性。与TPA相关的电离层电流曲线表明，沿着磁力线连接电磁铁尾翼和电离层的电流（场对准电流[FACs]）可能与“ J”形和“ L”形TPA有关编队。FAC可以通过与夜间磁场重新连接相关的快速等离子体流与较慢的背景磁尾等离子体流之间的速度剪切来生成。我们的观测结果无法阐明以前由磁流体动力学（MHD）模拟揭开的复杂大型TPA FAC结构。然而，