Flux ropes are ubiquitous at Earth's magnetopause and play important roles in energy transport between the solar wind and Earth's magnetosphere. In this study, structure and coalescence of the magnetopause flux ropes formed by multiple X line reconnection in cases with different southward interplanetary magnetic field (IMF) clock angles are investigated by using three‐dimensional global hybrid simulations. As the IMF clock angle decreases from 180°, the axial direction of the flux ropes becomes tilted relative to the equatorial plane, the length of the flux ropes gradually increases, and core field within flux ropes is formed by the increase in the guide field. The flux ropes are formed mostly near the subsolar point and then move poleward toward cusps. The flux ropes can eventually enter the cusps, during which their helical structure collapses, their core field weakens gradually, and their axial length decreases. When the IMF clock angle is large (i.e., the IMF is predominantly southward), the flux ropes can coalesce and form new ones with larger diameter. The coalescence between flux ropes can occur both near the subsolar point when they are newly formed and away from the subsolar point (e.g., in the southern hemisphere) when they move toward cusps. However, when the IMF clock angle is small (≤135°), we do not find coalescence between flux ropes.

中文翻译：

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磁更年期通量绳索的结构，聚结及其对IMF时钟角的依赖性：三维全局混合仿真

磁通绳在地球的磁层顶普遍存在，并且在太阳风和地球磁层之间的能量传输中起着重要作用。在这项研究中，通过使用三维全局混合模拟，研究了在不同南向行星际磁场（IMF）时钟角情况下，多条X线重新连接形成的磁更年期磁通束的结构和合并。当IMF时钟角从180°减小时，磁通量绳的轴向相对于赤道平面倾斜，磁通量绳的长度逐渐增加，并且由于引导场的增加而在磁通量绳内形成芯场。助焊剂绳大多形成在太阳下点附近，然后向尖点方向极移。助焊剂绳最终会进入风口，在此期间，其螺旋结构崩溃，其核心场逐渐减弱，轴向长度减小。当IMF时钟角较大时（即，IMF主要向南），助焊剂绳会聚结并形成直径更大的新绳。助焊绳之间的结合既可以在新近形成的近太阳能点附近发生，也可以在它们朝向尖头移动时远离亚太阳点（例如，在南半球）发生。但是，当IMF时钟角较小（≤135°）时，我们看不到助焊剂绳之间的合并。助焊绳之间的结合既可以在新近形成的近太阳能点附近发生，也可以在它们朝向尖头移动时远离亚太阳点（例如，在南半球）发生。但是，当IMF时钟角较小（≤135°）时，我们看不到助焊剂绳之间的合并。助焊绳之间的结合既可以在新近形成的近太阳能点附近发生，也可以在它们朝向尖头移动时远离亚太阳点（例如，在南半球）发生。但是，当IMF时钟角较小（≤135°）时，我们看不到助焊剂绳之间的合并。