行星际磁场对磁尾场向电流发生率的影响  

Effect of Interplanetary Magnetic Field on the Field-aligned Currents Occurrence in the Magnetotail

作　　者：程征伟[1] 史建魁[1] 张子迎[1] 刘振兴[1] 

机构地区：[1]中国科学院空间科学与应用研究中心空间天气学国家重点实验室,北京100190

出　　处：《空间科学学报》2013年第4期396-402,共7页Chinese Journal of Space Science

基　　金：国家自然科学基金项目(41274146;41074114);国家重点实验室专项基金共同资助

摘　　要：利用Cluster卫星的磁场和等离子体探测数据,研究了行星际磁场(IMF)时钟角(clock angle)Φ和锥角(cone angle)θ对磁尾等离子体片边界层(PSBL)区场向电流发生率的影响.当时钟角Φ>0时,磁尾场向电流的发生率较高,这表明磁尾场向电流的发生与昏向太阳风条件更为密切;当90°<|Φ|<180°时,场向电流的发生率较高,这表明场向电流的发生与南向IMF更为密切.当锥角θ<30°时(即IMF与日地连线夹角较小时)场向电流的发生率较低.而当θ>30°时,场向电流在90°<|Φ|<180°的情况下发生率明显增大,这说明南向IMF情况下,场向电流发生率明显增大.但是当|Φ|<90°时(北向IMF情况下),尽管θ很大,场向电流的发生率并未明显增大.当θ>70°时,且在140°<Φ<160°的行星际磁场条件下,磁尾等离子体片边界层区场向电流的发生率最大.Using the magnetic field and plasma data from Cluster spacecraft, the effect of Interplanetary Magnetic Field （IMF） clock angle Ф and cone angle θ on the Field-Aligned Currents （FAC） occurrence rate at the Plasma Sheet Boundary Layer （PSBL） in the magnetotail is investigated. There were more FAC cases occurred when IMF was within the 0°〈 Ф 〈 180° clock angle range comparing with the range of -180° 〈 Ф 〈 0°. It indicated that FAC occurrences were associated with duskward IMF （IMF By 〉 0）. Also, there were more FAC cases occurred when the IMF was within the 90°〈｜Ф｜〈180° clock angle range. It supported that FAC occurrences were associated with southward IMF （IMF Bz 〈 0）. Most of the FAC cases occurred when IMF was within the 0 〉 30° cone angle. In addition, a few of FAC cases occurred when the IMF clock angle was in the 〈 30° range regardless of the value of Ф. The occurrence rate of FAC was the largest when θ 〉 30°and 140°〈Ф〈160°.

关 键 词：场向电流 等离子体片边界层 行星际磁场 时钟角 锥角 

分 类 号：P353.2[天文地球—空间物理学]