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Title: Survey of radiation belt energetic electron pitch angle distributions based on the Van Allen Probes MagEIS measurements: Electron Pitch Angle Distributions

Abstract

A statistical survey of electron pitch angle distributions (PADs) is performed based on the pitch angle-resolved flux observations from the Magnetic Electron Ion Spectrometer (MagEIS) instrument on board the Van Allen Probes during the period from 1 October 2012 to 1 May 2015. By fitting the measured PADs to a sin nα form, where α is the local pitch angle and n is the power law index, we investigate the dependence of PADs on electron kinetic energy, magnetic local time (MLT), the geomagnetic Kp index, and L shell. The difference in electron PADs between the inner and outer belt is distinct. In the outer belt, the common averaged n values are less than 1.5, except for large values of the Kp index and high electron energies. The averaged n values vary considerably with MLT, with a peak in the afternoon sector and an increase with increasing L shell. In the inner belt, the averaged n values are much larger, with a common value greater than 2. The PADs show a slight dependence on MLT, with a weak maximum at noon. A distinct region with steep PADs lies in the outer edge of the inner belt where the electron flux ismore » relatively low. The distance between the inner and outer belt and the intensity of the geomagnetic activity together determine the variation of PADs in the inner belt. Finally, besides being dependent on electron energy, magnetic activity, and L shell, the results show a clear dependence on MLT, with higher n values on the dayside.« less

Authors:
 [1];  [1];  [2];  [3];  [3];  [4];  [5]
  1. Memorial Univ. of Newfoundland, St. John's, Newfoundland and Labrador (Canada)
  2. Wuhan Univ. (China). Dept. of Space Physics, School of Electronic Information
  3. Aerospace Corporation, El Segundo, CA (United States). Space Science Applications Lab.
  4. Univ. of New Hampshire, Durham, NH (United States)
  5. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
National Aeronautic and Space Administration (NASA); National Natural Science Foundation of China (NNSFC); USDOE
OSTI Identifier:
1402597
Report Number(s):
LA-UR-15-28231
Journal ID: ISSN 2169-9380; TRN: US1702999
Grant/Contract Number:  
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Volume: 121; Journal Issue: 2; Journal ID: ISSN 2169-9380
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Heliospheric and Magnetospheric Physics; pitch angle distributions; Van Allen Probes

Citation Formats

Shi, Run, Summers, Danny, Ni, Binbin, Fennell, Joseph F., Blake, J. Bernard, Spence, Harlan E., and Reeves, Geoffrey D. Survey of radiation belt energetic electron pitch angle distributions based on the Van Allen Probes MagEIS measurements: Electron Pitch Angle Distributions. United States: N. p., 2016. Web. doi:10.1002/2015JA021724.
Shi, Run, Summers, Danny, Ni, Binbin, Fennell, Joseph F., Blake, J. Bernard, Spence, Harlan E., & Reeves, Geoffrey D. Survey of radiation belt energetic electron pitch angle distributions based on the Van Allen Probes MagEIS measurements: Electron Pitch Angle Distributions. United States. doi:10.1002/2015JA021724.
Shi, Run, Summers, Danny, Ni, Binbin, Fennell, Joseph F., Blake, J. Bernard, Spence, Harlan E., and Reeves, Geoffrey D. Fri . "Survey of radiation belt energetic electron pitch angle distributions based on the Van Allen Probes MagEIS measurements: Electron Pitch Angle Distributions". United States. doi:10.1002/2015JA021724. https://www.osti.gov/servlets/purl/1402597.
@article{osti_1402597,
title = {Survey of radiation belt energetic electron pitch angle distributions based on the Van Allen Probes MagEIS measurements: Electron Pitch Angle Distributions},
author = {Shi, Run and Summers, Danny and Ni, Binbin and Fennell, Joseph F. and Blake, J. Bernard and Spence, Harlan E. and Reeves, Geoffrey D.},
abstractNote = {A statistical survey of electron pitch angle distributions (PADs) is performed based on the pitch angle-resolved flux observations from the Magnetic Electron Ion Spectrometer (MagEIS) instrument on board the Van Allen Probes during the period from 1 October 2012 to 1 May 2015. By fitting the measured PADs to a sinnα form, where α is the local pitch angle and n is the power law index, we investigate the dependence of PADs on electron kinetic energy, magnetic local time (MLT), the geomagnetic Kp index, and L shell. The difference in electron PADs between the inner and outer belt is distinct. In the outer belt, the common averaged n values are less than 1.5, except for large values of the Kp index and high electron energies. The averaged n values vary considerably with MLT, with a peak in the afternoon sector and an increase with increasing L shell. In the inner belt, the averaged n values are much larger, with a common value greater than 2. The PADs show a slight dependence on MLT, with a weak maximum at noon. A distinct region with steep PADs lies in the outer edge of the inner belt where the electron flux is relatively low. The distance between the inner and outer belt and the intensity of the geomagnetic activity together determine the variation of PADs in the inner belt. Finally, besides being dependent on electron energy, magnetic activity, and L shell, the results show a clear dependence on MLT, with higher n values on the dayside.},
doi = {10.1002/2015JA021724},
journal = {Journal of Geophysical Research. Space Physics},
issn = {2169-9380},
number = 2,
volume = 121,
place = {United States},
year = {2016},
month = {12}
}

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