High-speed solar wind with southward interplanetary magnetic field causes relativistic electron flux enhancement of the outer radiation belt via enhanced condition of whistler waves
High-speed solar wind with southward interplanetary magnetic field causes relativistic electron flux enhancement of the outer radiation belt via enhanced condition of whistler waves
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DOI：
10.1002/grl.50916
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发表时间：
2013-09-16
影响因子：
5.2
通讯作者：
Thomsen, M. F.
中科院分区：
文献类型：
--
作者：
Miyoshi, Y.;Kataoka, R.;Thomsen, M. F.
在高速太阳风事件期间，外辐射带的相对论电子通量有增加的趋势。然而，HSS事件并不总是导致大的通量增强。为了确定导致这种增强的HSS事件以及负责加速电子的机制，我们分析了超过一个太阳周期的长期等离子体数据集。我们表明，在HSS事件与南行星际磁场（IMF）主导的HSS（SBz-HSS），相对论电子被哨声模式波加速，然而，在HSS事件与北IMF主导的HSS，这种加速机制是无效的。外辐射带通量变化响应的差异是由与一系列亚暴相关的哨声模波-电子相互作用的差异引起的。在SBz-HSS事件中，热电子注入发生和热等离子体密度降低，由于等离子体层顶的收缩，通过哨声模式波激发引起相对论电子的大通量增强。这些结果解释了为什么大通量增强的相对论电子往往发生在SBz-HSS事件。
Relativistic electron flux in the outer radiation belt tends to increase during the high-speed solar wind stream (HSS) events. However, HSS events do not always cause large flux enhancement. To determine the HSS events that cause such enhancement and the mechanisms that are responsible for accelerating the electrons, we analyzed long-term plasma data sets, for periods longer than one solar cycle. We demonstrate that during HSS events with the southward interplanetary magnetic field (IMF)-dominant HSS (SBz-HSS), relativistic electrons are accelerated by whistler mode waves; however, during HSS events with the northward IMF-dominant HSS, this acceleration mechanism is not effective. The differences in the responses of the outer radiation belt flux variations are caused by the differences in the whistler mode wave-electron interactions associated with a series of substorms. During SBz-HSS events, hot electron injections occur and the thermal plasma density decreases due to the shrinkage of the plasmapause, causing large flux enhancement of relativistic electrons through whistler mode wave excitation. These results explain why large flux enhancement of relativistic electrons tends to occur during SBz-HSS events.