用银河宇宙线判定几个引起特大磁暴CME的运动方向

利用位于南北极尖区位置的McMurdo和Thule台站的宇宙线强度的观测数据，分析了几个引起特大磁暴CME的来向．分析结果表明，所选的与4个特大磁暴相关的CME基本是朝正对磁层顶的方向运动并与磁层作用的．通过对引起第23周两个特大磁暴的CME特征分析对照，发现CME的来向是影响磁暴强弱的一个因素．同样条件下，运动方向偏向地球一侧的CME引起的磁暴比正对地球的CME引起的磁暴要弱。

THE DETERMINATION OF TRAVLING DIRECTION OF SEVERAL CMEs CAUSING SEVERE GEOMAGNETIC STORM

Coronal Mass Ejections (CMEs) are important factors for the space weather. The geomagnetic storms with sudden commencement are caused by CMEs. CMEs with the south direction of Bz > 10 nT and high traveling speed can often cause intensive magnetic storm. But many problems keep unsolved on the relationship between a CME and the intensity of the relative geomagnetic storm. In this paper, the traveling directions of several coronal mass ejections causing severe geomagnetic storm are investigated by using the galactic cosmic ray data observed at McMurdo and Thule neutron monitor. If a CME's traveling direction straightly towards to magnetopause, then the variation in galactic cosmic ray intensity observed at the two stations should be almost the same. Several selected CME events are analyzed. The results show that the direction of the CME related to the geomagnetic storm on Dec.19, 1980 was almost dead against magnetopause, the situation was the same for the CMEs related to the geomagnetic storms on Jul.13, 1982, Nov.6, 2001 and Mar.31, 2001. The traveling direction of the CME related to the geomagnetic storm on Jul.15, 2000 is slightly directed to south of the earth. By comparing the intensity of the geomagnetic storm on March 31, 2001 and July 15, 2000 and comparing the disturbed solar wind driven by corresponding CME, it is thought that the traveling direction of a CME is a factor having impact on the intensity of the geomagnetic storm caused by the CME. For a CME, the more deflection of its traveling direction towards the magnetopause, the weaker the geomagnetic storm caused by it.