1994年2月21日行星际激波引起的磁暴  

THE MAGNETIC STORM RESULTED FROM THE INTERPLANETARY SHOCK OF FEBRUARY 21, 1994

作　　者：刘绍亮[1] 郭建广[1] 宗秋刚 B.Wilken 傅绥燕[3] 

机构地区：[1]中国科学技术大学地球和空间科学系,合肥230026 [2]Max-Planck-Institute [3]北京大学地球物理系

出　　处：《空间科学学报》2002年第3期203-211,共9页Chinese Journal of Space Science

基　　金：国家自然科学基金(49874035;49834040);中国科学技术大学创新工程研究基金共同资助项目

摘　　要：利用Imp-8,Geotail和Goes-6等卫星资料,研究了1994年2月21日0900UT到达地球磁层的行星际激波引起的磁暴期间,从太阳风向磁层传输能量的有关问题.结果指出:（1）南向行星际磁场（IMF）的长持续时间不是太阳风向磁层输能的必要条件.南北振荡的,较强IMF也能产生显著的能量传输;（2）行星际扰动磁场通过弓激波和磁层顶后扰动磁能增加,增幅将近5倍;（3）在磁层内扰动磁场的Bz分量在1×10-4Hz附近显著被吸收.这一低频扰动磁场可能是磁暴期间导致氧离子和质子等环电流粒子向内扩散并被加速的原因之一.On February 21, 1994, at 0903 UT a strong interplanetary shock crossed the Geotail spacecraft while it is at (x, y, Z)GSE = (-26.9,60.8, -2.3) Re. The shock hasalso been observed or detected its effect by other satellites such as Imp-8, Goes-6, Goes-7 and Lanl successively. This shock resulted in magnetic index Dst dropped down to lower than -100nT and AE shows an explicit increase. At the same time the geomagnetic field fluctuated intensively, the flux increased of various energetic particles at geosynchronous orbit. These means there are notable energy coupling between the solar wind and the magnetosphere. Gonzalez et al. pointed out the IMF Bz component should be lower than -10 nT and its duration longer than 3 hours for a strong magnetic storm, of which, Dst index lower than -100 nT, but the character of the shock studied in this paper is that there have no long duration of IMF southward Bz event but only large amplitude fluctuation northward and southward in the downstream of the shock, furthermore the enhanced value and average value for the - Bz is lower than that for the +BZ. If we think that the energy transfer from the solar wind into the magnetosphere take place only during IMF Bz component is negative, then this means the rate of energy transferred into ring current is far quicker than the dissipation of the ring current. This result shows that the duration time of southward IMF is not the essential condition for energy transfer from solar wind into the magnetosphere, if the southward IMF has large amplitude and short time-duration, but repeated many times there may be accumulated notable energy in the ring current owing to the rate of ring current dissipation is very slow relative to the rate of energy pouring into the ring current. In addition, for above result we have analyzed the power spectrum property of the magnetic field, it is shown that the disturbance magnetic energy enhanced near five times after the disturbance field crosses the bow shock and the magnetopause. Nakada et al. pointed out th

关 键 词：1994年2月21日 行星际激波 磁暴 环电流 功率谱 磁层 

分 类 号：P353[天文地球—空间物理学]