Ring current electron dynamics during geomagnetic storms based on the Van Allen Probes measurements
Ring current electron dynamics during geomagnetic storms based on the Van Allen Probes measurements
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基于范艾伦探测器测量的地磁暴期间环流电子动力学
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
L. Lanzerotti
中科院分区：
文献类型：
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作者：
H. Zhao;X. Li;D. Baker;S. Claudepierre;J. Fennell;J. Blake;B. Larsen;R. Skoug;H. Funsten;R. Friedel;G. Reeves;H. Spence;D. Mitchell;L. Lanzerotti
利用货车艾伦探测器上的氦、氧、质子和电子质谱仪离子谱仪、相对论电子-质子望远镜和辐射带风暴探测器离子成分实验等仪器的综合测量，对环电流电子和离子进行了对比研究，探讨了高能电子在环电流动力学中的作用。几十到几百keV的电子和几十keV的质子注入到内磁层的深度经常发生;注入后，电子在内带衰减缓慢，但质子在低L区衰减非常快。低能质子和高能电子之间也存在着有趣的相似性。在两个磁暴期间，我们详细研究了环电流电子和离子能量密度和能量含量的演化，一个是中等磁暴，一个是强烈磁暴。结果表明，环流电子对环流能含量的贡献远小于环流离子（中等磁暴约12%，强磁暴约7%），在磁暴主相环流电子能含量中，<35 keV电子占主导地位。虽然电子的能量含量通常比离子的能量含量小得多，但在中等磁暴期间，环电流电子能量含量的增强可达到环电流离子能量含量的30%左右，表明环电流电子具有更强的动态特征，电子在环电流的建立中起着重要作用。环电流电子能量密度在午夜和黎明较高，而在中午和黄昏较低。
Based on comprehensive measurements from Helium, Oxygen, Proton, and Electron Mass Spectrometer Ion Spectrometer, Relativistic Electron‐Proton Telescope, and Radiation Belt Storm Probes Ion Composition Experiment instruments on the Van Allen Probes, comparative studies of ring current electrons and ions are performed and the role of energetic electrons in the ring current dynamics is investigated. The deep injections of tens to hundreds of keV electrons and tens of keV protons into the inner magnetosphere occur frequently; after the injections the electrons decay slowly in the inner belt but protons in the low L region decay very fast. Intriguing similarities between lower energy protons and higher‐energy electrons are also found. The evolution of ring current electron and ion energy densities and energy content are examined in detail during two geomagnetic storms, one moderate and one intense. The results show that the contribution of ring current electrons to the ring current energy content is much smaller than that of ring current ions (up to ~12% for the moderate storm and ~7% for the intense storm), and <35 keV electrons dominate the ring current electron energy content at the storm main phases. Though the electron energy content is usually much smaller than that of ions, the enhancement of ring current electron energy content during the moderate storm can get to ~30% of that of ring current ions, indicating a more dynamic feature of ring current electrons and important role of electrons in the ring current buildup. The ring current electron energy density is also shown to be higher at midnight and dawn while lower at noon and dusk.