Effect of EMIC waves on relativistic and ultrarelativistic electron populations: Ground- based and Van Allen Probes observations
Effect of EMIC waves on relativistic and ultrarelativistic electron populations: Ground- based and Van Allen Probes observations
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DOI：
10.1002/2013gl059024
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发表时间：
2014-03-16
影响因子：
5.2
通讯作者：
Wygant, J.
中科院分区：
文献类型：
--
作者：
Usanova, M. E.;Drozdov, A.;Wygant, J.
研究了2012年10月11日中等磁暴恢复阶段电磁离子回旋（EMIC）波对相对论和超相对论电子损失和俯仰角散射的影响。在货车艾伦探测器上原位观测到EMIC波活动，并在地面上共轭地观测到加拿大阵列的磁活动实时调查，时间间隔为18小时。然而，既没有增强沉淀的> 0.7 MeV的电子，也没有减少货车艾伦探针90度俯仰角超相对论电子通量观察。计算的辐射带电子俯仰角扩散速率表明，快速俯仰角扩散被限制在低俯仰角，不能达到90度。这是第一次，从观测和建模的角度来看，我们展示了EMIC波触发超相对论性关键点EMIC波活动与MeV电子的沉淀无关EMIC波不会耗尽超高能电子，相对论性带低至90度的EMIC波导致具有类似于2-8 MeV能量的低俯仰角电子的损失
We study the effect of electromagnetic ion cyclotron (EMIC) waves on the loss and pitch angle scattering of relativistic and ultrarelativistic electrons during the recovery phase of a moderate geomagnetic storm on 11 October 2012. The EMIC wave activity was observed in situ on the Van Allen Probes and conjugately on the ground across the Canadian Array for Real-time Investigations of Magnetic Activity throughout an extended 18 h interval. However, neither enhanced precipitation of >0.7MeV electrons nor reductions in Van Allen Probe 90 degrees pitch angle ultrarelativistic electron flux were observed. Computed radiation belt electron pitch angle diffusion rates demonstrate that rapid pitch angle diffusion is confined to low pitch angles and cannot reach 90 degrees. For the first time, from both observational and modeling perspectives, we show evidence of EMIC waves triggering ultrarelativistic (similar to 2-8MeV) electron loss but which is confined to pitch angles below around 45 degrees and not affecting the core distribution.Key Points EMIC wave activity is not associated with precipitation of MeV electrons EMIC waves do not deplete the ultra-relativistic belt down to 90 degrees EMIC waves cause loss of low pitch angle electrons with energies similar to 2-8 MeV