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

Title: Nonstorm time dropout of radiation belt electron fluxes on 24 September 2013

Abstract

Radiation belt electron flux dropouts during the main phase of geomagnetic storms have received increasing attention in recent years. Here we focus on a rarely reported nonstorm time dropout event observed by Van Allen Probes on 24 September 2013. Within several hours, the radiation belt electron fluxes exhibited a significant (up to 2 orders of magnitude) depletion over a wide range of radial distances ( L > 4.5), energies (~500 keV to several MeV) and equatorial pitch angles (0° ≤ α e ≤ 180°). STEERB simulations show that the relativistic electron loss in the region L = 4.5–6.0 was primarily caused by the pitch angle scattering of observed plasmaspheric hiss and electromagnetic ion cyclotron waves. Furthermore, our results emphasize the complexity of radiation belt dynamics and the importance of wave-driven precipitation loss even during nonstorm times.

Authors:
 [1];  [1];  [2];  [3];  [4];  [4];  [1];  [1];  [1];  [5];  [6];  [7];  [8]
  1. Univ. of Science and Technology of China, Hefei (China)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); New Mexico Consortium, Los Alamos, NM (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. Univ. of California, Los Angeles, CA (United States)
  5. Univ. of New Hampshire, Durham, NH (United States). Dept. of Physics
  6. Univ. of Colorado, Boulder, CO (United States)
  7. The Aerospace Corp., Los Angeles, CA (United States)
  8. Univ. of Minnesota, Minneapolis, MN (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:
1291235
Report Number(s):
LA-UR-16-23140
Journal ID: ISSN 2169-9380
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Name: Journal of Geophysical Research. Space Physics; Journal ID: ISSN 2169-9380
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Heliospheric and Magnetospheric Physics

Citation Formats

Su, Zhenpeng, Gao, Zhonglei, Reeves, Geoffrey D., Funsten, Herbert O., Zhu, Hui, Li, Wen, Zheng, Huinan, Wang, Yuming, Wang, Shui, Spence, H. E., Baker, D. N., Blake, J. B., and Wygant, J. R. Nonstorm time dropout of radiation belt electron fluxes on 24 September 2013. United States: N. p., 2016. Web. doi:10.1002/2016JA022546.
Su, Zhenpeng, Gao, Zhonglei, Reeves, Geoffrey D., Funsten, Herbert O., Zhu, Hui, Li, Wen, Zheng, Huinan, Wang, Yuming, Wang, Shui, Spence, H. E., Baker, D. N., Blake, J. B., & Wygant, J. R. Nonstorm time dropout of radiation belt electron fluxes on 24 September 2013. United States. doi:10.1002/2016JA022546.
Su, Zhenpeng, Gao, Zhonglei, Reeves, Geoffrey D., Funsten, Herbert O., Zhu, Hui, Li, Wen, Zheng, Huinan, Wang, Yuming, Wang, Shui, Spence, H. E., Baker, D. N., Blake, J. B., and Wygant, J. R. 2016. "Nonstorm time dropout of radiation belt electron fluxes on 24 September 2013". United States. doi:10.1002/2016JA022546. https://www.osti.gov/servlets/purl/1291235.
@article{osti_1291235,
title = {Nonstorm time dropout of radiation belt electron fluxes on 24 September 2013},
author = {Su, Zhenpeng and Gao, Zhonglei and Reeves, Geoffrey D. and Funsten, Herbert O. and Zhu, Hui and Li, Wen and Zheng, Huinan and Wang, Yuming and Wang, Shui and Spence, H. E. and Baker, D. N. and Blake, J. B. and Wygant, J. R.},
abstractNote = {Radiation belt electron flux dropouts during the main phase of geomagnetic storms have received increasing attention in recent years. Here we focus on a rarely reported nonstorm time dropout event observed by Van Allen Probes on 24 September 2013. Within several hours, the radiation belt electron fluxes exhibited a significant (up to 2 orders of magnitude) depletion over a wide range of radial distances (L > 4.5), energies (~500 keV to several MeV) and equatorial pitch angles (0° ≤ αe ≤ 180°). STEERB simulations show that the relativistic electron loss in the region L = 4.5–6.0 was primarily caused by the pitch angle scattering of observed plasmaspheric hiss and electromagnetic ion cyclotron waves. Furthermore, our results emphasize the complexity of radiation belt dynamics and the importance of wave-driven precipitation loss even during nonstorm times.},
doi = {10.1002/2016JA022546},
journal = {Journal of Geophysical Research. Space Physics},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 7
}

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

Citation Metrics:
Cited by: 6works
Citation information provided by
Web of Science

Save / Share:
  • The Van Allen radiation belts surrounding the Earth are filled with MeV-energy electrons. This region poses ionizing radiation risks for spacecraft that operate within it, including those in geostationary orbit (GEO) and medium Earth orbit. In order to provide alerts of electron flux enhancements, 16 prediction models of the electron log-flux variation throughout the equatorial outer radiation belt as a function of the McIlwain L parameter were developed using the multivariate autoregressive model and Kalman filter. Measurements of omnidirectional 2.3 MeV electron flux from the Van Allen Probes mission as well as >2 MeV electrons from the GOES 15 spacecraftmore » were used as the predictors. Furthermore, we selected model explanatory parameters from solar wind parameters, the electron log-flux at GEO, and geomagnetic indices. For the innermost region of the outer radiation belt, the electron flux is best predicted by using the Dst index as the sole input parameter. For the central to outermost regions, at L≥4.8 and L ≥5.6, the electron flux is predicted most accurately by including also the solar wind velocity and then the dynamic pressure, respectively. The Dst index is the best overall single parameter for predicting at 3 ≤ L ≤ 6, while for the GEO flux prediction, the K P index is better than Dst. Finally, a test calculation demonstrates that the model successfully predicts the timing and location of the flux maximum as much as 2 days in advance and that the electron flux decreases faster with time at higher L values, both model features consistent with the actually observed behavior.« less
  • From Aug. 7 to 13, 1959, the Explorer VI earth satellite passed twice a day through the heart of the outer Van Allen radiation region at latitudes near the magnetic equator. Part II presents evidence that any particles affected by the Capetown magnetic anomaly do not have trajectories which would pass through the position of the experimentally observed minimum in the outer belt. It is concluded that the minimum cannot be taken as evidence either for the effect of the anomaly on the trapped radiation, or for support of the neutron albedo source for the outer zone electrons. Part IIImore » describes the radiation detectors aboard Explorer Vl, and presents information on the energy spectra and fluxes of the trapped electrons along a typical pass through the outer Van Allen radiation region. The findings are based on analysis of data from electron calibrations of the radiation detectors. Part IV presents data on the differential energy spectrum of an assumed power law form for trapped protons in the inner belt as determined from data received from the ion chamber and Geiger counter aboard Explorer VI earth satellite. (C.H.)« less
  • Using the albedo neutron decay source, the energy spectrum of trapped protons in the inner belt has been calculated from 10 io 700 Mev. This calculation differs from those of Singer and Hess in that a nuclear interaction term, in addition to the energy loss term, has been used in the continuity equation for the steady-state condition. The spectrum agrees well with the published data. This agreement is strong evidence for the albedo neutron decay source. It also indicates that nonadiabatic losses are small for the particles measured here. A second small stack of nuclear emulsions was flown at themore » lower edge of the inner radiation belt 11 days after the large solar flare of May 10. 1959. The ratio of the proton flux measured on the second flight to that on the first one is 0.8 plus or minus 0.1, indicating that the solar flare had little or no effect on the proton content of the inner belt. A flux of 2 plus or minus 1 tritons/cm/sup 2/ sec between 126 and 200 Mev was observed; it is attributed to collisions of trapped protons wiih air nuclei. No other nuclei heavier than protons were seen. (auth)« less