The closure of region‐1 field‐aligned current in MHD simulation
The closure of region‐1 field‐aligned current in MHD simulation
复制标题
DOI：
10.1029/97gl01292
复制
发表时间：
1997-06
影响因子：
5.2
通讯作者：
P. Janhunen;H. Koskinen
中科院分区：
文献类型：
--
作者：
P. Janhunen;H. Koskinen
在我们的全球MHD模拟中，我们研究了区域1场向电流系统的闭合路径，并发现了一些有趣的结果。在离开电离层的黄昏侧后，电流很早就偏离了场向方向，并转向太阳。在穿过磁层顶附近的速度剪切区（这是一个发电机区）后，它沿着磁层顶向上爬升，或多或少地与磁场对齐。因此，它再次向太阳弯曲。然而，当接近正午-午夜子午面（GSM坐标中的Y=0平面）时，电流变得更加垂直于磁场。它在大约X=2±1，Z=11±1处通过Y=0平面。在晨侧，闭合路径是晚侧的镜像。因此，关闭路径似乎比通常想象的更偏向白天。本文从磁流体压力平衡方程出发，对向阳面弯曲现象给出了简单的物理解释。
We have studied the closure path of Region‐1 field‐aligned current system in our global MHD simulation and found some interesting results. After leaving the ionosphere on the eveningside the current deviates from the field‐aligned direction rather early and bends towards the Sun. After passing through the velocity shear region near the magnetopause, which is a generator region, it climbs up along the magnetopause, being more or less field‐aligned. Because of this it again bends sunward. When approaching the noon‐midnight meridian plane (Y=0 plane in GSM coordinates), however, the current becomes more perpendicular to the magnetic field. It passes through the Y=0 plane at about X=2±1, Z=11±1. On the morningside the closure path is a mirror reflection of that on the evening side. Thus the closure path seems to reside more on the dayside than perhaps usually thought. We give a simple physical explanation for the dayside bending, which is based on the MHD pressure balance equation.