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Rapid Enhancements of Relativistic Electrons in the Earth’s Outer Radiation Belt caused by the Intense Substorms: A Statistical Study
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  • Chao ling Tang,
  • Chang Yang,
  • JingRun Chen,
  • Xu Wang,
  • Binbin Ni,
  • Zhenpeng Su,
  • Jichun Zhang
Chao ling Tang
Shandong University, Weihai

Corresponding Author:[email protected]

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Chang Yang
Changsha University of Science and Technology
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JingRun Chen
School of Space Science and Physics, Shandong University
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Xu Wang
School of Space Science and Physics, Shandong University
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Binbin Ni
Wuhan University
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Zhenpeng Su
University of Science and Technology of China
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Jichun Zhang
University of New Hampshire
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Abstract

Using the data from Van Allen Probe A and B, we investigate rapid enhancements of relativistic electrons in the Earth’s outer radiation belt caused by the intense substorms (AEmax > ~ 900 nT) for 29 events from January 2013 to April 2015. These intense substorms may occur during the storm main phase or recovery phase. Based on the different substorm evolution characteristics, the intense substorms are divided into isolated substorm activities and continuous substorm activities. In this study, we set a criterion for rapid enhancements when the electron phase space densities (PSDs) for μ = 1096, 2290, and 3311 MeV/G increased by more than 2 times in 9 hours. In the time interval of 9 hours, the local acceleration of chorus waves is the dominant process for accelerating the seed populations (100s keV) up to MeV energies. Our statistical results show that enhanced chorus waves and seed electrons during the intense substorms are observed in the outer radiation belt. Continuous substorm activities can more rapidly (< 9 h) and efficiently accelerate relativistic electrons in the outer radiation belt than isolated substorm activity. During the intense substorms, MeV electron injections could contribute to rapid enhancements of relativistic electrons in the outer radiation belt. Our statistical study suggests that the intense substorms during geomagnetic storms have a significant effect on the rapid variations of relativistic electron dynamics.