2000年7月重大太阳事件的极隙区纬度观测研究

20 0 0年 7月 ,太阳表面发生了一系列的耀斑与日冕物质抛射事件 ,最大耀斑能级达X5 .7/3 B。地球表面发生相应特大磁暴 ,Dst指数最大负偏达 - 3 0 0 n T。中国南极中山站地处极隙区纬度 ,白天位于磁层极隙区 ,夜间位于极盖区 ,以多种高空大气物理观测设备详细记录了该磁暴过程。对有关数据的分析表明 ,高能粒子引起电离层吸收急剧增加 ,测高仪数据两天多信号空白 ,宇宙噪声吸收显著增加 ;地磁 Pc3 /5脉动增加与行星际磁场南向分量密切对应 ,显示行星际磁流体波对激发磁层脉动的贡献 ;磁暴主相期间 ,Pc3 /5脉动大幅度增加 ;极区地磁水平分量随南向行星际磁场变化 ,但滞后近 8小时 ;Dst指数与南向行星际磁场密切相关 ,磁暴受控于高度负偏的南向行星际磁场

STUDY AND OBSERVATION OF THE GREAT SOLAR EVENT IN JULY OF 2000 AT CUSP LATITUDE

A series of solar flare and coronal mass ejection (CME) event occurred in July of 2000, particularly the largest flare (X5.7/3B) with CME on 14 July since 1989, which induced a great geomagnetic storm with Dst index reaching -300nT. A set of data is obtained from the Chinese Antarctic Zhongshan Station (ZHS,INT Lat. 74.5°, L≈14), which is located at cusp latitude, and from the ACE satellite. Analyzed these data and got the results as follows: a lot of solar highly energized particles penetrated into the polar ionosphere and ionized it, which significantly increased the cosmic noise absorption (CNA) and blanked the DPS 4 data for more than two days. The magnetic pulsation in Pc 3/5 frequency band on the ground has a high relation with the fluctuation of interplanetary magnetic field (IMF) Bz, which shows the contribution of interplanetary MHD waves to the Pc 3/5 pulsation on the ground. The Pc 3/5 pulsation was intensified much during the great magnetic storm. H component of the magnetic field at ZHS varied with the IMF Bz but lagged about 8-10h, while Dst index responded to the variation of the IMF Bz very quickly, which suggested that the magnetic storm occurred at low latitude firstly and then effected the ionospheric current at high latitude.