Anomalous aspects of magnetosheath flow and of the shape and oscillations of the magnetopause during an interval of strongly northward interplanetary magnetic field
Anomalous aspects of magnetosheath flow and of the shape and oscillations of the magnetopause during an interval of strongly northward interplanetary magnetic field
复制标题
强向北行星际磁场期间磁鞘流以及磁层顶的形状和振荡的异常方面
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发表时间：
1993
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影响因子：
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通讯作者：
Lazarus
中科院分区：
文献类型：
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作者：
.. SHENG;Chen;Margaret;G.;Jack;T.;Gosling;Raymond;J.;Walker;Lazarus
1978年2月15日，行星际磁场（IMF）的方向稳定地向北持续了12个多小时。ISEE 1号和2号航天器位于近远地点，位于磁尾的黎明侧。IMP 8几乎对称地位于黄昏侧翼的磁鞘中，IMP 7位于太阳风的上游。利用等离子体和磁场数据，我们发现：(1)磁尾两侧的磁鞘流速度稳定地超过太阳风速度20%；(2)在黎明磁层顶持续存在周期为~ 5min的表面波和非常非正弦波形，在黄昏磁鞘中存在类似周期的波；(3)磁尾在反日距离为15re时停止耀斑。我们认为，磁尾耀斑的减少与开放磁通量的减少和亚太阳磁层顶距离的增加是一致的，磁鞘流的加速是由北向IMF覆盖场结构中的磁张力实现的。三维磁流体力学模拟结果支持这一现象学模型。
On February 15, 1978, the orientation of the interplanetary magnetic field (IMF) remained steadily northward for more than 12 hours. The ISEE 1 and 2 spacecraft were located near apogee on the dawnside flank of the magnetotail. IMP 8 was almost symmetrically located in the magnetosheath on the dusk flank and IMP 7 was upstream in the solar wind. Using plasma and magnetic field data, we show that (1) the magnetosheath flow speed on the flanks of the magnetotail steadily exceeded the solar wind speed by 20%, (2) surface waves of ∼5-min period and very nonsinusoidal waveform were persistently present on the dawn magnetopause and waves of similar period were present in the dusk magnetosheath, and (3) the magnetotail ceased to flare at an antisunward distance of 15 RE. We propose that the acceleration of the magnetosheath flow is achieved by magnetic tension in the draped field configuration for northward IMF and that the reduction of tail flaring is consistent with a decreased amount of open magnetic flux and a larger standoff distance of the subsolar magnetopause. Results of a three-dimensional magnetohydrodynamic simulation support this phenomenological model.