Measuring the dayside reconnection rate during an interval of due northward interplanetary magnetic field
Measuring the dayside reconnection rate during an interval of due northward interplanetary magnetic field
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DOI：
10.5194/angeo-22-4243-2004
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发表时间：
2004-01-01
影响因子：
1.9
通讯作者：
Sofko, G
中科院分区：
文献类型：
--
作者：
Chisham, G;Freeman, MP;Sofko, G
这项研究首次详细测量了北半球电离层在行星际磁场向北延伸期间重联电场的时空分布。使用SuperDARN高频雷达网的全球对流测绘提供了对北极电离层对流电场的全球估计。结合对重联X线电离层足迹的测量，确定重联电场沿整个X线的时空变化。空间变化的形状在整个区间内是稳定的，尽管其幅度确实随着时间的变化而变化。因此，沿X线的总重联势在时间上是可变的，但其典型的大小与低空卫星天桥测量的跨极盖势是一致的。重联测量是沿着Tsyganenko模型磁力线从电离层绘制出来的，以确定波瓣磁层顶上最可能的重联位置。根据在确定电离层X线长度时所作的假设，叶磁层顶上的X线长度估计与6-11R-E的范围相似。在波瓣磁层顶上的重联电场估计与峰值重联区的0.2 mV/m相似。
This study presents, for the first time, detailed spatiotemporal measurements of the reconnection electric field in the Northern Hemisphere ionosphere during an extended interval of northward interplanetary magnetic field. Global convection mapping using the SuperDARN HF radar network provides global estimates of the convection electric field in the northern polar ionosphere. These are combined with measurements of the ionospheric footprint of the reconnection X-line to determine the spatiotemporal variation of the reconnection electric field along the whole X-line. The shape of the spatial variation is stable throughout the interval, although its magnitude does change with time. Consequently, the total reconnection potential along the X-line is temporally variable but its typical magnitude is consistent with the cross-polar cap potential measured by low-altitude satellite overpasses. The reconnection measurements are mapped out from the ionosphere along Tsyganenko model magnetic field lines to determine the most likely reconnection location on the lobe magnetopause. The X-line length on the lobe magnetopause is estimated to be similar to6-11 R-E in extent, depending on the assumptions made when determining the length of the ionospheric X-line. The reconnection electric field on the lobe magnetopause is estimated to be similar to0.2 mV/m in the peak reconnection region.