【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.更多还原

【Abstract】 Using the magnetic field and plasma data from Cluster spacecraft,the effect of Interplanetary Magnetic Field(IMF) clock angleΦand cone angle 6 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°<Φ<180°clock angle range comparing with the range of -180°<Φ<0°.It indicated that FAC occurrences were associated with duskward IMF(IMF B_y>0).Also,there were more FAC cases occurred when the IMF was within the 90°<|Φ|<180°clock angle range.It supported that FAC occurrences were associated with southward IMF(IMF B_z<0).Most of the FAC cases occurred when IMF was within theθ>30°cone angle.In addition,a few of FAC cases occurred when the IMF clock angle was in theθ<30°range regardless of the value ofΦ.The occurrence rate of FAC was the largest whenθ>30°and 140°<Φ<160°.更多还原