利用CHAMP卫星磁场数据分析研究了2004年11月7日至8日巨磁暴(Dst〈-200nT)期间大尺度场向电流的分布特征.把方向相同且时间连续的一段场向电流定义为一个电流片,分析结果表明,伴随磁暴的发展,在卫星飞过的两个扇区(早上扇区0200-0400MLT及下午扇区1400-1600MLT)中的大尺度场向电流分布呈现不同的纬向分布特征:随着地磁扰动的增强,早上扇区电流片分布范围向高纬扩展;而下午扇区电流片分布范围则显著地向低纬扩展.与地磁活动SYM-H和AE指数对比分析得出,早上扇区的大尺度电流片的分布特征更多地受到亚暴活动的影响,而下午扇区的电流片分布则明显反映出磁暴环电流活动的特征.
Abstract Using the high-resolution vector magnetic field data of the CHAMP satellite, we investigate the distribution of large-scale FACs during the great magnetic storm on Nov. 7-8, 2004. The results show that there are different latitudinal distribution characteristics between the morning sector (0200-0400MLT) and afternoon sector (1400-1600MLT). In morning sector, the extent of FACs expand to higher latitudes along with increasing geomagnetic disturbance, while the afternoon sector FACs expand to lower latitudes. In terms of SYM-H and AE magnetic indices, we find that the large-scale FACs in morning sector are significantly affected by substorm activities, and in afternoon sector the large-scale FACs mainly indicate the fluctuations of the ring current in storm time.