Probing the boundary between antiparallel and component reconnection during southward interplanetary magnetic field conditions
Probing the boundary between antiparallel and component reconnection during southward interplanetary magnetic field conditions
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DOI：
10.1029/2007ja012270
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发表时间：
2007-08
影响因子：
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通讯作者：
K. Trattner;J. Mulcock;S. Petrinec;S. Fuselier
中科院分区：
文献类型：
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作者：
K. Trattner;J. Mulcock;S. Petrinec;S. Fuselier
[1] 关于磁重联的主要悬而未决的问题之一是，在太阳风和行星际磁场 (IMF) 的特定条件下，重联将在地球磁层顶发生。文献中讨论了两种情况：(1) 反平行重联，发生在磁层磁场和 IMF 反平行（剪切角约为 180°）的情况下；(2) 分量重联，据报道，磁层磁场和 IMF 之间的剪切角低至 50°。两种重新连接情景之间的区别对于从太阳风到磁层的能量和动量转移非常重要。在这里，我们报告了一种方法，利用极地航天器上的环形成像质量角摄谱仪在其穿过北磁层尖点时进行三维等离子体观测来计算到重联线的距离，然后沿着模型磁场线追踪回到磁层顶的距离。 130 个事件的结果表明，一般来说，磁重联发生在穿过日侧磁层顶的延长线上（即与分量重联场景一致）。然而，在强向日或反向日 IMF 条件 (BX) 期间，重连位置类似于高纬度的反平行重连模型，并且不会作为单个倾斜重连线穿过日侧磁层顶。这些结果表明，根据具体的 IMF 条件，两种重联情况都可能发生在磁层顶。
[1] One of the major outstanding questions about magnetic reconnection is where reconnection will occur at the Earth's magnetopause for specific conditions of the solar wind and the interplanetary magnetic field (IMF). There are two scenarios discussed in the literature: (1) antiparallel reconnection, which occurs where the magnetospheric magnetic field and the IMF are antiparallel (shear angle of approximately 180°) and (2) component reconnection, where shear angles between the magnetospheric field and the IMF as low as 50° have been reported. The distinction between the two reconnection scenarios is important for the energy and momentum transfer from the solar wind to the magnetosphere. Here we report on a method using three-dimensional plasma observations from the Toroidal Imaging Mass-Angle Spectrograph instrument on the Polar spacecraft as it passes through the northern magnetospheric cusp to calculate the distance to the reconnection line and subsequently trace the distance along model magnetic field lines back to the magnetopause. Results from 130 events reveal that in general, magnetic reconnection occurs along an extended line across the dayside magnetopause (i.e., consistent with the component reconnection scenario). During strong sunward or antisunward IMF conditions (BX), however, the reconnection location resembles the antiparallel reconnection model at high latitudes and does not cross the dayside magnetopause as a single tilted reconnection line. These results show that either reconnection scenario can occur at the magnetopause, depending on the specific IMF conditions.