In Situ Observations of a Magnetosheath High-Speed Jet Triggering Magnetopause Reconnection
In Situ Observations of a Magnetosheath High-Speed Jet Triggering Magnetopause Reconnection
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DOI：
10.1002/2017gl076525
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发表时间：
2018-02-28
影响因子：
5.2
通讯作者：
Plaschke, F.
中科院分区：
文献类型：
--
作者：
Hietala, H.;Phan, T. D.;Plaschke, F.
磁鞘高速射流——局部动态压力增强，通常大小类似于 1 个地球半径——每小时多次撞击白天磁层顶。在这里，我们提出了第一个原位测量结果，表明这种撞击触发了磁层顶重新连接。我们使用了 2007 年 8 月 7 日珍珠串结构中的五次亚暴期间事件和宏观相互作用航天器的观测结果。该航天器记录了磁鞘喷流撞击期间的磁层顶进出运动（V-N 类似于沿磁层顶法线方向的 -300km/s）。没有证据表明撞击前交叉口重新连接，但三个探测器观察到撞击后重新连接。我们推断，喷流冲击压缩了原本厚（60-70 d(i)）、高磁剪切（140-160 度的磁层顶），直到它变得足够薄，可以发生重新连接。因此，磁鞘高速喷流可以充当突发白天重新连接的驱动力。
Magnetosheath high-speed jets-localized dynamic pressure enhancements typically of similar to 1 Earth radius in size-impact the dayside magnetopause several times per hour. Here we present the first in situ measurements suggesting that such an impact triggered magnetopause reconnection. We use observations from the five Time History of Events and Macroscale Interactions during Substorms spacecraft in a string-of-pearls configuration on 7 August 2007. The spacecraft recorded magnetopause in-and-out motion during an impact of a magnetosheath jet (V-N similar to -300km/s along the magnetopause normal direction). There was no evidence for reconnection for the preimpact crossing, yet three probes observed reconnection after the impact. We infer that the jet impact compressed the originally thick (60-70 d(i)), high magnetic shear (140-160 degrees magnetopause until it was thin enough for reconnection to occur. Magnetosheath high-speed jets could therefore act as a driver for bursty dayside reconnection.