Effect of the dawn-dusk interplanetary magnetic field By on the field-aligned current system
Effect of the dawn-dusk interplanetary magnetic field By on the field-aligned current system
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黎明-黄昏行星际磁场By对场对准电流系统的影响
DOI：
10.1029/2009ja014590
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发表时间：
2010-01-16
影响因子：
2.8
通讯作者：
Wang, C.
中科院分区：
文献类型：
--
作者：
Guo, X. C.;Wang, C.
在我们的全球MHD模拟中，将一个恒定的晨昏B-y分量设置为行星际磁场（IMF）条件，以研究IMF B-y对磁层场向电流（FAC）闭合的影响。在稳态磁层结果的基础上，我们从电离层追踪FAC的流线，以绘制磁层中电流流线的全球几何形状。与IMF纯粹向北或向南的情况不同，引入占主导地位的IMF B-y显著改变了当前流线的拓扑结构。尖电流和地幔电流的出现，和FAC的对称性跨越中午-夜间的纬向平面打破电离层。除了在北方或南半球的自闭合电流，三种类型的电流流线连接两个电离层显示从模拟结果。第一种电流，包括尖点电流，起源于南电离层，流入北方电离层。第二个电流，主要是地幔电流，和尾电流连接在一起，形成一个单一的电流系统，沿着沿着螺旋状的路径穿过大部分的磁层，并通过远磁尾的两个叶闭合。第三股电流从南部流出，进入北方电离层，最终通过弓形激波而不是磁层顶闭合，从而将两个电离层连接起来。定量的结果，并讨论了四种类型的电流流线，并指出，占主导地位的IMF B-Y条件的弓激波电流应包括在磁层-电离层电流系统。
A constant dawn-dusk B-y component is set as an interplanetary magnetic field (IMF) condition in our global MHD simulations to investigate the effects of IMF B-y on the closure of the field-aligned current (FAC) in the magnetosphere. On the basis of the steady state magnetosphere results, we trace streamlines of FAC from the ionosphere to draw the global geometry of current streamlines in the magnetosphere. Unlike those cases in which the IMF is purely northward or southward, the introduction of the dominant IMF B-y significantly changes the topologies of the current streamlines. Cusp and mantle currents arise, and the symmetry of the FAC across the noon-night meridional plane breaks in the ionosphere. In addition to the self-closed currents in the Northern or Southern hemispheres, three more types of current streamlines connecting the two ionospheres are shown from the simulation results. The first current, including the cusp current, originates from the southern ionosphere and flows into the northern ionosphere. The second current, mainly the mantle current, and the tail current are connected to form a single current system, threading most of the magnetosphere along a spiral-like path and closing through the two lobes in the far magnetotail. The third current flowing out of the southern and into the northern ionosphere connects the two ionospheres by finally closing through the bow shock instead of the magnetopause. Quantitative results are presented and discussed for the four types of current streamlines and indicate that for the dominant IMF B-y conditions the bow shock current should be included among the magnetosphere-ionosphere current system.