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本文通过分析两次大磁暴期间的中性原子(ENA)通量数据,试图揭示环电流离子通量的变化规律,进一步探讨环电流的形成和损失机制,以及磁暴和亚暴的关系.两次磁暴期间ENA通量的变化呈现出一些重要的特征:(1)通量随能量的增高而快速降低,磁暴主相期间高能端通量所占比重增大;(2)通量比例曲线的起伏远比通量曲线的起伏要平缓;(3)通量的起伏与AE指数之间没有简单的对应关系;(4)磁暴恢复相开始前,ENA通量出现短时间的猛烈增长,特别是低能端通量的增长异常迅速;(5)Dst/SYM-H指数快速恢复期间,ENA通量的变化表现为两个完全不同的阶段:先降低,后增大.忽略影响ENA通量的其他次要因素,ENA通量的上述特征直接反映了环电流的发展规律.环电流离子通量随能量的增高快速下降,磁暴主相期间可能由于高能O+的增加使得能谱有所变硬.离子主要受南向行星际磁场(IMF)所引起的对流电场的驱动注入到环电流区域,通量的变化大体上是无色散的.亚暴活动与环电流的增长没有直接的因果关系,但亚暴活动会引起环电流离子通量的短时间尺度波动.恢复相开始前,环电流离子在昏侧区域发生堆积,使得局部离子通量变大.这可能是由于屏蔽电场的形成削弱了内磁层对流电场,造成离子在磁层顶的逃逸损失过程减弱.在Dst/SYM-H指数的快速恢复期间,环电流离子通量的衰减速度也可能发生阶段性变化.这说明Dst/SYM-H指数并不能准确反映环电流的强度,环电流的衰减过程可能具有比先快后慢更为复杂的阶段性模式.
In this paper, by analyzing the data of neutral atom (ENA) flux during the two large storms, we try to reveal the variation regularity of the ring current flux and further discuss the formation and loss mechanism of ring current, and the relationship between storms and sub-storms. The changes of ENA fluxes during magnetic storms show some important features: (1) the flux decreases rapidly with increasing energy, and the proportion of high energy fluxes increases during the main phase of the storms; (2) the fluctuations of the flux proportion curves (3) There is no simple correspondence between the flux fluctuation and the AE index; (4) The ENA flux shows a drastic increase over a short period of time before the start of the storm recovery phase, especially the low energy (5) During rapid recovery of Dst / SYM-H index, the changes of ENA flux showed two completely different phases: decrease first and increase later, ignoring other times that affect the ENA flux The above characteristics of the ENA flux directly reflect the development of the ring current, and the flux of the ring current rapidly decreases with the increase of the energy, and the energy spectrum may be harden due to the increase of the high energy O + during the main phase of the magnetic storm. Caused by a southward interplanetary magnetic field (IMF) And the change of flux is largely non-dispersive.The sub-storm activity has no direct causal relationship with the increase of the ring current, but the sub-storm activity will cause the ring current to flow in a short time Scale fluctuations before the recovery phase, the ring current ions accumulate in the faint side of the region, making the local ion flux larger.This may be due to the formation of shielding electric field weakens the inner magnetic layer convection electric field, resulting in the escape of ions at the top of the magnetosphere The loss process is weakened.During the rapid recovery of the Dst / SYM-H index, the decay rate of the ring current ion flux may also change step by step, indicating that the Dst / SYM-H index does not accurately reflect the ring current intensity, The decay process may have a more complicated phase pattern than the faster one.