Multiscale Nature of the Magnetotail Reconnection Onset
Multiscale Nature of the Magnetotail Reconnection Onset
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DOI：
10.1029/2021gl093065
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发表时间：
2021-05
影响因子：
5.2
通讯作者：
M. Sitnov;T. Motoba;M. Swisdak
中科院分区：
文献类型：
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作者：
M. Sitnov;T. Motoba;M. Swisdak
亚暴磁场数据的挖掘揭示了两条 X 线的形成，之前是薄电流片 (TCS) 尾端的通量积累。在这些预发生重连接特征的指导下进行了三维颗粒细胞模拟，同时还考虑了弱外部驱动、TCS 的负电荷以及电子作为载流子的主导地位。模拟揭示了有趣的多尺度图景。在全球范围内，它们显示出两条 X 线的形成，在靠近地球的地方存在更强的磁场变化和不均匀电场。 X线出现之前，形成了两个发散的电子流出区域，嵌入到单个发散的离子流出图案中，并在开始后转变为更快的电子尺度重联射流。陀螺参数的分布表明重联是由离子提供的，然后是电子退磁。总体流动和陀螺仪分布与 MMS 观测结果一致。
Mining of substorm magnetic field data reveals the formation of two X‐lines preceded by the flux accumulation at the tailward end of a thin current sheet (TCS). Three‐dimensional particle‐in‐cell simulations guided by these pre‐onset reconnection features are performed, taking also into account weak external driving, negative charging of TCS and domination of electrons as current carriers. Simulations reveal an interesting multiscale picture. On the global scale, they show the formation of two X‐lines, with stronger magnetic field variations and inhomogeneous electric fields found closer to Earth. The X‐line appearance is preceded by the formation of two diverging electron outflow regions embedded into a single diverging ion outflow pattern and transforming into faster electron‐scale reconnection jets after the onset. Distributions of the agyrotropy parameters suggest that reconnection is provided by ion and then electron demagnetization. The bulk flow and agyrotropy distributions are consistent with MMS observations.