A unified model of the magnetotail convection in geomagnetically quiet and active times
A unified model of the magnetotail convection in geomagnetically quiet and active times
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DOI：
10.1029/97ja01617
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发表时间：
1998-03-01
影响因子：
2.8
通讯作者：
Maezawa, K
中科院分区：
文献类型：
--
作者：
Nishida, A;Mukai, T;Maezawa, K
对地尾的观测表明，在地磁平静时期，向北的磁力线在遥远的磁尾中是向尾的，而在近地磁尾中是向地的。当行星际磁场（IMF） B-z向北且\B-y\大于或等于B-z时，这些看似不相容的观测结果可以用发生在远尾的磁重联来解释，在那里中性片被扭曲了几十度。根据这一解释，北向磁场线的尾部对流发生在重联线之外，因为重联磁场线从中性片的北侧穿过中性片的南侧，通过中性片的扭转，可以到处具有北向的极性。因此，无论是在地磁活跃时期还是在安静时期，即在向南和向北（B-y大于或等于B-z）的IMF条件下，重联都可以成为磁尾中等离子体加速和加热的一般机制。Geotail和DE 2的观测都表明，由重联形成的闭合磁力线在地磁平静时期和活跃时期都是通过内磁层对流回到日侧的。这表明，在磁层顶与北向IMF （B-y大于等于B-z）的日侧重联中，除了经典的北向IMF尖峰重联模型中考虑的开放场线外，还包括封闭场线。
Geotail observations have shown that during geomagnetically quiet times the northward magnetic field lines are convected tailward in the distant tail while they are convected earthward in the near-Earth magnetotail. These seemingly incompatible observations when the interplanetary magnetic field (IMF) B-z is northward and \B-y\ greater than or equal to B-z can be explained by the magnetic reconnection which occurs in the distant tail where the neutral sheet is twisted by tens of degrees. According to this interpretation, the tailward convection of the northward field lines occurs beyond the reconnection line because the reconnected field lines that cross the neutral sheet from Its northern side to the southern side can have the northward polarity everywhere by virtue of the twisting of the neutral sheet. Hence the reconnection can be the generic mechanism of the plasma acceleration and heating in the magnetotail in both geomagnetically active and quiet times, namely, under both southward and northward (with \B-y\ greater than or equal to B-z) IMF conditions. Both Geotail and DE 2 observations suggest that the closed field lines that are formed by the reconnection return to the dayside by convecting through the inner magnetosphere in geomagnetically quiet times as well as in active times. This suggests that the dayside reconnection with the northward IMF (with \B-y\ greater than or equal to B-z) on the magnetopause involves the closed field lines in addition to the open field lines as considered in the classical cusp reconnection model under the northward IMF.