中文摘要：

行星际激波是导致地球磁层一电离层系统发生扰动的重要原因之一，其可以通过对磁层一电离层系统电流体系的改变来影响地磁变化．本文采用全球三维磁流体力学数值模拟方法，分析了行星际激波作用下电离层等效电流体系的即时响应．模拟结果表明，在激波作用下伴随着异常场向电流对的产生，电离层在午前午后出现一对反向的等效电流涡．这对涡旋一边向极侧和夜侧运动，一边经历强度增强和减弱直至消失的过程．激波过后等效电流体系图像逐渐演化为激波下游行星际条件控制的典型图像．这个响应过程与行星际激波强度有关，激波强度越强，则反向的等效电流涡旋强度越大，寿命也就越短．

英文摘要：

Interplanetary （IP） shocks, one of the disturbances, could affect the geo-magnetic field important causes of the magnetosphere ionosphere by changing the current systems in the magneto- sphere ionosphere region. By using a global three dimensional MHD simulation code, we analyze the immediate responses of the Equivalent Current Systems （ECS） in the Earth＇s ionosphere to the impact of IP shocks. The model results show that after the shock arrival a pair of abnormal Field-Aligned Current （FAC） appears, flowing into and out of the ionosphere on the dusk and dawnside respectively. Also developed in the ionosphere is the two-cell ECS： an anticlockwise circulation in the dawn hemisphere and a clockwise one in the dusk hemisphere. The two ECS vortices shift poleward and tailward after their formation. In the meantime, their intensities increase at first and then decrease to virtually disappear within tens of seconds. At last the ECS pattern reaches a quasi- steady state which is controlled by the interplanetary conditions downstream of the IP shock. The quantitative characteristics of such response processes depend on the intensity of the IP shock： for a stronger shock, the two-cell ECS becomes more intense, and its lifetime is shorter.