Rapid rebuilding of the outer radiation belt
Rapid rebuilding of the outer radiation belt
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DOI：
10.1029/2011ja016516
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发表时间：
2011-09
影响因子：
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通讯作者：
A. Glocer;M. Fok;T. Nagai;G. Tóth;T. Guild;J. Blake
中科院分区：
文献类型：
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作者：
A. Glocer;M. Fok;T. Nagai;G. Tóth;T. Guild;J. Blake
[1]Akebono号航天器上的辐射监测器最近的观测表明，在不到几个小时的时间尺度上发生了几次2.5兆电子伏以上辐射带电子增强的情况。NOAA/POES卫星和TALK 1卫星上的探测器也有类似的改进。这些间隔比典型的径向扩散或波粒相互作用所能解释的要短。我们选择了高速流期间发生的两个所谓的“快速重建”事件（2008年9月4日和2009年7月22日），并使用配置有全球磁层、辐射带、环电流和电离层电动力学模型的空间天气建模框架对其进行了模拟。与观测结果相比，我们的模拟产生了较弱和延迟的偶极化，但模拟中的相关感应电场仍然足够强，可以快速传输和加速MeV电子，从而导致高能电子通量增强，比观察到的要弱一些。然而，计算的通量增强和偶极化被认为是定性与观测一致。两者合计，模拟结果和观测支持的结论，暴时的磁层磁场中的偶极事件导致强的径向传输和辐射带电子的散射。
[1] Recent observations by the radiation monitor (RDM) on the spacecraft Akebono have shown several cases of >2.5 MeV radiation belt electron enhancements occurring on timescales of less than a few hours. Similar enhancements are also seen in detectors on board the NOAA/POES and TWINS 1 satellites. These intervals are shorter than typical radial diffusion or wave-particle interactions can account for. We choose two so-called “rapid rebuilding” events that occur during high speed streams (4 September 2008 and 22 July 2009) and simulated them with the Space Weather Modeling Framework configured with global magnetosphere, radiation belt, ring current, and ionosphere electrodynamics model. Our simulations produce a weaker and delayed dipolarization as compared to observations, but the associated inductive electric field in the simulations is still strong enough to rapidly transport and accelerate MeV electrons resulting in an energetic electron flux enhancement that is somewhat weaker than is observed. Nevertheless, the calculated flux enhancement and dipolarization is found to be qualitatively consistent with the observations. Taken together, the modeling results and observations support the conclusion that storm-time dipolarization events in the magnetospheric magnetic field result in strong radial transport and energization of radiation belt electrons.