地球等离子体层顶与地磁活动的关系研究

本文利用IMAGE卫星EUV相机观测的等离子体层图像，并采用最小L算法反演磁赤道面等离子体层顶位置.文中选取了2000-2002年间的3579幅等离子体层图像，并反演得到了时间间隔为1 h的等离子体层顶位置数据库，包含48899个等离子体层顶位置数据.利用该数据库统计研究了等离子体层顶位形随地磁活动的变化特性.统计发现等离子体层顶高度依赖地磁活动，与地磁指数Kp、Dst和AE均呈负相关，且等离子体层顶随地磁指数的变化趋势具有显著的MLT分布特性；亚暴活动对等离子体层顶演化的贡献在不同地磁活动期间有所不同，磁暴期间亚暴活动的贡献小，而地磁平静期亚暴的贡献大.本文研究工作为后续建立等离子体层顶模型和了解等离子体层顶的动态结构提供了重要研究基础.

Study on the relationship between the Earth's plasmapause and geomagnetic activity

Based on the plasmaspheric images observed by IMAGE EUV imager, the plasmapause locations on the magnetic equatorial plane are reconstructed with the Minimum L Algorithm. 3579 plasmaspheric images are selected from 2000 to 2002 and a plasmapause location database is compiled containing 48899 plasmapause locations in 1 h MLT intervals. This database is used to statistically study the relationships between the plasmapause locations and the geomagnetic activities. It is found that the plasmapause shapes are highly dependent on the geomagnetic activities, and the plasmapause locations are negatively correlated with Kp, Dst and AE with their variation tendencies all significantly changing with MLT. It is also found that the effects of the substorm activity on the plasmapause locations are different under different geomagnetic conditions with the effects being larger for quiet periods compared with disturbed periods. The results in this paper will provide an important basis for future construction of a plasmapause model and understanding the dynamic structure of the plasmapause.