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Title: Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015

Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (storm time ring current index) value reaching –223 nT. On 22 June 2015 another strong storm (Dst reaching –204 nT) was recorded. These two storms each produced almost total loss of radiation belt high-energy (E ≳ 1 MeV) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 MeV in kinetic energy. The energized outer zone electrons showed a rich variety of pitch angle features including strong “butterfly” distributions with deep minima in flux at α = 90°. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported “impenetrable barrier” at L ≈ 2.8 was pushed inward, but not significantly breached, and no E ≳ 2.0 MeV electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Altogether, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [4] ;  [1] ;  [1] ;  [1] ;  [5] ;  [5] ;  [6] ;  [7] ;  [8]
  1. Univ. of Colorado, Boulder, CO (United States)
  2. Goddard Space Flight Center, NASA, Greenbelt, MD (United States)
  3. MIT Haystack Observatory, Westford, MA (United States)
  4. The Aerospace Corporation, Los Angeles, CA (United States)
  5. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  6. Univ. of New Hampshire, Durham, NH (United States)
  7. Univ. of Iowa, Iowa City, IA (United States)
  8. Univ. of Minnesota, Twin Cities, Minneapolis, MN (United States)
Publication Date:
OSTI Identifier:
1304817
Report Number(s):
LA-UR--16-22086
Journal ID: ISSN 2169-9380
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Volume: 121; Journal Issue: 7; Journal ID: ISSN 2169-9380
Publisher:
American Geophysical Union
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
NASA; USDOE
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES heliospheric and magnetospheric physics