阿尔文涨落与地球磁层亚暴

本文讨论了一种地球磁层的亚暴机制。当行星际磁场有大的南向分量时,磁层的位形可由基本闭式转变为开式。磁鞘中的阿尔文波可以携带超过10~(18)尔格/秒的能流传入磁层尾部,并将能量耗散于等离子体片中。等离子体片中的粒子被加热和加速后,注入近地空间,产生环电流和极区亚暴。计算了剪切流场中阿尔文波的传播过程,以及磁层中阿尔文波的耗散。将本文的结算与[4]中的结果合在一起,可以说明当行星际磁场转向南时,容易发生地球磁层亚暴,但这两者并非一一对应的关系,行星际磁场没有南向分量时也可以发生地球磁层亚暴。

In this paper, a mechanism of the earth's magnetospheric substorm is discussed. The magnetospheric configuration is converted from the nearly closed one into an open one, when the IMF has a large southward component. The Alfven waves with energy greater than 10" ergs/sec can pass through from the magnetosheath into the magne-totail, and the wave energy is dissipated in the plasma sheet. The particles are heated and accelerated in the plasma sheet, and then injected into the near earth space, and produce the ring current and auroral substorm. The propagation process of the Alfven wave in a shear velocity field is calculated, and the dissipation of Alfven waves in the magnetosphere is given.Using the results of this paper and the results of [4] we can explain the phenomena that the substorm is easy to appear when the IMF turn to south. But the sub-storm does not correspond to the IMF turning south uniquely; the substorm can be produced even if the IMF is directed to north.