skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: The influences of solar wind pressure and interplanetary magnetic field on global magnetic field and outer radiation belt electrons

Abstract

Using the Van Allen Probe in situ measured magnetic field and electron data, we examine the solar wind dynamic pressure and interplanetary magnetic field (IMF) effects on global magnetic field and outer radiation belt relativistic electrons (≥1.8 MeV). The dynamic pressure enhancements (>2 nPa) cause the dayside magnetic field increase and the nightside magnetic field reduction, whereas the large southward IMFs (B z-IMF < –2nT) mainly lead to the decrease of the nightside magnetic field. In the dayside increased magnetic field region (magnetic local time (MLT) ~ 06:00–18:00, and L > 4), the pitch angles of relativistic electrons are mainly pancake distributions with a flux peak around 90° (corresponding anisotropic index A > 0.1), and the higher-energy electrons have stronger pancake distributions (the larger A), suggesting that the compression-induced betatron accelerations enhance the dayside pancake distributions. However, in the nighttime decreased magnetic field region (MLT ~ 18:00–06:00, and L ≥ 5), the pitch angles of relativistic electrons become butterfly distributions with two flux peaks around 45° and 135° (A < 0). The spatial range of the nighttime butterfly distributions is almost independent of the relativistic electron energy, but it depends on the magnetic field day-night asymmetry and the interplanetary conditions.more » The dynamic pressure enhancements can make the nighttime butterfly distribution extend inward. The large southward IMFs can also lead to the azimuthal expansion of the nighttime butterfly distributions. As a result, these variations are consistent with the drift shell splitting and/or magnetopause shadowing effect.« less

Authors:
 [1];  [1];  [1]; ORCiD logo [2];  [3];  [4]
  1. Beihang Univ., Beijing (China)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Univ. of Colorado, Boulder, CO (United States)
  4. Univ. of New Hampshire, Durham, NH (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
National Aeronautic and Space Administration (NASA); USDOE
OSTI Identifier:
1304818
Report Number(s):
LA-UR-16-23137
Journal ID: ISSN 0094-8276
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 43; Journal Issue: 14; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Heliospheric and Magnetospheric Physics

Citation Formats

Yu, J., Li, L. Y., Cao, J. B., Reeves, Geoffrey D., Baker, D. N., and Spence, H.. The influences of solar wind pressure and interplanetary magnetic field on global magnetic field and outer radiation belt electrons. United States: N. p., 2016. Web. doi:10.1002/2016GL069029.
Yu, J., Li, L. Y., Cao, J. B., Reeves, Geoffrey D., Baker, D. N., & Spence, H.. The influences of solar wind pressure and interplanetary magnetic field on global magnetic field and outer radiation belt electrons. United States. doi:10.1002/2016GL069029.
Yu, J., Li, L. Y., Cao, J. B., Reeves, Geoffrey D., Baker, D. N., and Spence, H.. Thu . "The influences of solar wind pressure and interplanetary magnetic field on global magnetic field and outer radiation belt electrons". United States. doi:10.1002/2016GL069029. https://www.osti.gov/servlets/purl/1304818.
@article{osti_1304818,
title = {The influences of solar wind pressure and interplanetary magnetic field on global magnetic field and outer radiation belt electrons},
author = {Yu, J. and Li, L. Y. and Cao, J. B. and Reeves, Geoffrey D. and Baker, D. N. and Spence, H.},
abstractNote = {Using the Van Allen Probe in situ measured magnetic field and electron data, we examine the solar wind dynamic pressure and interplanetary magnetic field (IMF) effects on global magnetic field and outer radiation belt relativistic electrons (≥1.8 MeV). The dynamic pressure enhancements (>2 nPa) cause the dayside magnetic field increase and the nightside magnetic field reduction, whereas the large southward IMFs (Bz-IMF < –2nT) mainly lead to the decrease of the nightside magnetic field. In the dayside increased magnetic field region (magnetic local time (MLT) ~ 06:00–18:00, and L > 4), the pitch angles of relativistic electrons are mainly pancake distributions with a flux peak around 90° (corresponding anisotropic index A > 0.1), and the higher-energy electrons have stronger pancake distributions (the larger A), suggesting that the compression-induced betatron accelerations enhance the dayside pancake distributions. However, in the nighttime decreased magnetic field region (MLT ~ 18:00–06:00, and L ≥ 5), the pitch angles of relativistic electrons become butterfly distributions with two flux peaks around 45° and 135° (A < 0). The spatial range of the nighttime butterfly distributions is almost independent of the relativistic electron energy, but it depends on the magnetic field day-night asymmetry and the interplanetary conditions. The dynamic pressure enhancements can make the nighttime butterfly distribution extend inward. The large southward IMFs can also lead to the azimuthal expansion of the nighttime butterfly distributions. As a result, these variations are consistent with the drift shell splitting and/or magnetopause shadowing effect.},
doi = {10.1002/2016GL069029},
journal = {Geophysical Research Letters},
number = 14,
volume = 43,
place = {United States},
year = {Thu Jul 28 00:00:00 EDT 2016},
month = {Thu Jul 28 00:00:00 EDT 2016}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 7works
Citation information provided by
Web of Science

Save / Share: