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Title: Formation of energetic electron butterfly distributions by magnetosonic waves via Landau resonance

Radiation belt electrons can exhibit different types of pitch angle distributions in response to various magnetospheric processes. Butterfly distributions, characterized by flux minima at pitch angles around 90°, are broadly observed in both the outer and inner belts and the slot region. Butterfly distributions close to the outer magnetospheric boundary have been attributed to drift shell splitting and losses to the magnetopause. However, their occurrence in the inner belt and the slot region has hitherto not been resolved. In this study, by analyzing the particle and wave data collected by the Van Allen Probes during a geomagnetic storm, we combine test particle calculations and Fokker-Planck simulations to reveal that scattering by equatorial magnetosonic waves is a significant cause for the formation of energetic electron butterfly distributions in the inner magnetosphere. Finally, another event shows that a large-amplitude magnetosonic wave in the outer belt can create electron butterfly distributions in just a few minutes.
Authors:
 [1] ;  [2] ; ORCiD logo [3] ;  [4] ;  [4] ;  [4] ;  [3] ;  [3] ;  [5] ;  [3] ;  [6] ;  [7] ;  [7] ;  [7] ;  [8] ; ORCiD logo [9] ;  [10] ;  [11] ;  [12]
  1. Peking Univ., Beijing (China). Inst. of Space Physics and Applied Technology; Univ. of California, Los Angeles, CA (United States). Dept. of Atmospheric and Oceanic Sciences
  2. Wuhan Univ. (China). School of Electronic Information. Dept. of Space Physics
  3. Univ. of California, Los Angeles, CA (United States). Dept. of Atmospheric and Oceanic Sciences
  4. Peking Univ., Beijing (China). Inst. of Space Physics and Applied Technology
  5. Univ. of Texas, Dallas, TX (United States). W. B. Hanson Center for Space Sciences. Dept. of Physics
  6. Univ. of Colorado, Boulder, CO (United States). Lab. for Atmospheric and Space Physics
  7. Univ. of Iowa, Iowa City, IA (United States). Dept. of Physics and Astronomy
  8. The Aerospace Corporation, El Segundo, CA (United States). Space Science Applications Lab.
  9. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Space Science and Applications Group
  10. Univ. of New Hampshire, Durham, NH (United States). Inst. for the Study of Earth, Oceans, and Space
  11. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  12. Memorial Univ. of Newfoundland, St. John's, NL (Canada). Dept. of Mathematics and Statistics
Publication Date:
Report Number(s):
LA-UR-16-20481
Journal ID: ISSN 0094-8276
Grant/Contract Number:
AC52-06NA25396; AGS-1103064; NNX13AI61G; NNX14AN85G; NAS5-01072; 967399; 921647; 1001057397:01; 13-041; 41374166; 41274167; 41204120; 41474141; 2011CB811404
Type:
Accepted Manuscript
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 43; Journal Issue: 7; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Peking Univ., Beijing (China); Univ. of California, Los Angeles, CA (United States); Wuhan Univ. (China)
Sponsoring Org:
USDOE; National Science Foundation (NSF); National Aeronautic and Space Administration (NASA); Johns Hopkins Univ. Applied Physics Lab. (APL) (United States); National Natural Science Foundation of China (NNSFC); Nature Science and Engineering Research Council of Canada (NSERC)
Contributing Orgs:
Univ. of Texas, Dallas, TX (United States); Univ. of Colorado, Boulder, CO (United States); The Aerospace Corporation, El Segundo, CA (United States); Memorial Univ. of Newfoundland, St. John's, NL (Canada); Univ. of Iowa, Iowa City, IA (United States); Univ. of New Hampshire, Durham, NH (United States)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; heliospheric and magnetospheric physics; magnetosonic waves; butterfly distributions; Landau resonance; energetic electrons; radiation belt
OSTI Identifier:
1338751