Prompt enhancement of the Earth's outer radiation belt due to substorm electron injections

C. L. Tang, J. C. Zhang, G. D. Reeves, Z. P. Su, D. N. Baker, H. E. Spence, H. O. Funsten, J. B. Blake, J. R. Wygant

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


We present multipoint simultaneous observations of the near-Earth magnetotail and outer radiation belt during the substorm electron injection event on 16 August 2013. Time History of Events and Macroscale Interactions during Substorms A in the near-Earth magnetotail observed flux-enhanced electrons of 300 keV during the magnetic field dipolarization. Geosynchronous orbit satellites also observed the intensive electron injections. Located in the outer radiation belt, RBSP-A observed enhancements of MeV electrons accompanied by substorm dipolarization. The phase space density (PSD) of MeV electrons at L*~5.4 increased by 1 order of magnitude in 1 h, resulting in a local PSD peak of MeV electrons, which was caused by the direct effect of substorm injections. Enhanced MeV electrons in the heart of the outer radiation belt were also detected within 2 h, which may be associated with intensive substorm electron injections and subsequent local acceleration by chorus waves. Multipoint observations have shown that substorm electron injections not only can be the external source of MeV electrons at the outer edge of the outer radiation belt (L*~5.4) but also can provide the intensive seed populations in the outer radiation belt. These initial higher-energy electrons from injection can reach relativistic energy much faster. The observations also provide evidence that enhanced substorm electron injections can explain rapid enhancements of MeV electrons in the outer radiation belt.

Original languageEnglish (US)
Pages (from-to)11,826-11,838
JournalJournal of Geophysical Research: Space Physics
Issue number12
StatePublished - Dec 1 2016

Bibliographical note

Funding Information:
This work was supported by the National Natural Science Foundation of China grants 41004075 and 41274170, the National Basic Research Program of China (2012CB825601), and the Shandong Province Natural Science Foundation grant ZR2014DM003. We acknowledge CDAWeb ( for the use of AE and SYM-H data. All the Van Allen Probes data are publicly available at by the MagEIS and REPT instruments, by the EMFISIS instrument, and by the EFW instrument. We thank V. Angelopoulos for the use of data from the THEMIS mission. We acknowledge the THEMIS investigators for the use of the data and the analysis software. THEMIS data are available at GOES data are made available at LANL-GEO data are provided by Geoffrey D. Reeves. Global distribution of chorus wave amplitudes is provided by W. Li at University of California, Los Angeles. C.L. Tang thanks L. Dai, W. Li, Aaron Breneman, and George Hospodarsky for their helpful discussions.

Publisher Copyright:
©2016. American Geophysical Union. All Rights Reserved.


  • plasma sheet
  • relativistic electrons
  • substorm injections
  • the Earth's radiation belt


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