Direct observations of a surface eigenmode of the dayside magnetopause
Direct observations of a surface eigenmode of the dayside magnetopause
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DOI：
10.1038/s41467-018-08134-5
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发表时间：
2019-02-12
影响因子：
16.6
通讯作者：
Angelopoulos, V.
中科院分区：
文献类型：
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作者：
Archer, M. O.;Hietala, H.;Angelopoulos, V.
磁层和周围等离子体之间的突然边界，即磁层顶，长期以来一直被认为支持表面波。有人提出，作用在边界上的脉冲可能导致电离层在日面捕获这些波，从而产生磁层顶表面的驻波或本征模式。迄今为止还没有发现这方面的直接观测证据，而对间接证据的研究也被证明是不确定的，这导致人们猜测这种机制可能不会发生。通过在一个罕见的孤立的快速等离子体射流撞击边界期间使用偶然的多点航天器观测，在这里我们表明，由此产生的磁层顶运动和磁层超低频波在明确的频率是一致的，只能用磁层顶表面特征模态来解释。因此，我们通过直接观测表明，这种影响全球磁层系统的机制确实发生了。
The abrupt boundary between a magnetosphere and the surrounding plasma, the magnetopause, has long been known to support surface waves. It was proposed that impulses acting on the boundary might lead to a trapping of these waves on the dayside by the ionosphere, resulting in a standing wave or eigenmode of the magnetopause surface. No direct observational evidence of this has been found to date and searches for indirect evidence have proved inconclusive, leading to speculation that this mechanism might not occur. By using fortuitous multipoint spacecraft observations during a rare isolated fast plasma jet impinging on the boundary, here we show that the resulting magnetopause motion and magnetospheric ultra-low frequency waves at well-defined frequencies are in agreement with and can only be explained by the magnetopause surface eigenmode. We therefore show through direct observations that this mechanism, which should impact upon the magnetospheric system globally, does in fact occur.