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Title: Reproducing the observed energy-dependent structure of Earth's electron radiation belts during storm recovery with an event-specific diffusion model

Abstract

Here, we present dynamic simulations of energy-dependent losses in the radiation belt “slot region” and the formation of the two-belt structure for the quiet days after the 1 March storm. The simulations combine radial diffusion with a realistic scattering model, based data-driven spatially and temporally resolved whistler-mode hiss wave observations from the Van Allen Probes satellites. The simulations reproduce Van Allen Probes observations for all energies and L shells (2–6) including (a) the strong energy dependence to the radiation belt dynamics (b) an energy-dependent outer boundary to the inner zone that extends to higher L shells at lower energies and (c) an “S-shaped” energy-dependent inner boundary to the outer zone that results from the competition between diffusive radial transport and losses. We find that the characteristic energy-dependent structure of the radiation belts and slot region is dynamic and can be formed gradually in ~15 days, although the “S shape” can also be reproduced by assuming equilibrium conditions. The highest-energy electrons (E > 300 keV) of the inner region of the outer belt (L ~ 4–5) also constantly decay, demonstrating that hiss wave scattering affects the outer belt during times of extended plasmasphere. Through these simulations, we explain the full structuremore » in energy and L shell of the belts and the slot formation by hiss scattering during storm recovery. We show the power and complexity of looking dynamically at the effects over all energies and L shells and the need for using data-driven and event-specific conditions.« less

Authors:
 [1]; ORCiD logo [2];  [2];  [1];  [3];  [4];  [5];  [5];  [6];  [7];  [8]
  1. CEA, DAM, DIF, Arpajon (France)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); New Mexico Consortium, Los Alamos, NM (United States)
  3. New Mexico Consortium, Los Alamos, NM (United States); Space Science Institute, Boulder, CO (United States)
  4. Institute of Atmospheric Physics ASCR, Prague (Czech Republic); Charles Univ., Prague (Czech Republic)
  5. Univ. of Iowa, Iowa City, IA (United States)
  6. Aerospace Corp., El Segundo, CA (United States)
  7. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  8. The Johns Hopkins Univ., Laurel, MD (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:
1340971
Report Number(s):
LA-UR-16-23141
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: 11; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; heliospheric and magnetospheric physics; radiation belts; wave particle interactions; electron losses; electron lifetimes; whistler waves

Citation Formats

Ripoll, J. -F., Reeves, Geoffrey D., Cunningham, Gregory Scott, Loridan, V., Denton, M., Santolik, O., Kurth, W. S., Kletzing, C. A., Turner, D. L., Henderson, M. G., and Ukhorskiy, A. Y.. Reproducing the observed energy-dependent structure of Earth's electron radiation belts during storm recovery with an event-specific diffusion model. United States: N. p., 2016. Web. doi:10.1002/2016GL068869.
Ripoll, J. -F., Reeves, Geoffrey D., Cunningham, Gregory Scott, Loridan, V., Denton, M., Santolik, O., Kurth, W. S., Kletzing, C. A., Turner, D. L., Henderson, M. G., & Ukhorskiy, A. Y.. Reproducing the observed energy-dependent structure of Earth's electron radiation belts during storm recovery with an event-specific diffusion model. United States. doi:10.1002/2016GL068869.
Ripoll, J. -F., Reeves, Geoffrey D., Cunningham, Gregory Scott, Loridan, V., Denton, M., Santolik, O., Kurth, W. S., Kletzing, C. A., Turner, D. L., Henderson, M. G., and Ukhorskiy, A. Y.. 2016. "Reproducing the observed energy-dependent structure of Earth's electron radiation belts during storm recovery with an event-specific diffusion model". United States. doi:10.1002/2016GL068869. https://www.osti.gov/servlets/purl/1340971.
@article{osti_1340971,
title = {Reproducing the observed energy-dependent structure of Earth's electron radiation belts during storm recovery with an event-specific diffusion model},
author = {Ripoll, J. -F. and Reeves, Geoffrey D. and Cunningham, Gregory Scott and Loridan, V. and Denton, M. and Santolik, O. and Kurth, W. S. and Kletzing, C. A. and Turner, D. L. and Henderson, M. G. and Ukhorskiy, A. Y.},
abstractNote = {Here, we present dynamic simulations of energy-dependent losses in the radiation belt “slot region” and the formation of the two-belt structure for the quiet days after the 1 March storm. The simulations combine radial diffusion with a realistic scattering model, based data-driven spatially and temporally resolved whistler-mode hiss wave observations from the Van Allen Probes satellites. The simulations reproduce Van Allen Probes observations for all energies and L shells (2–6) including (a) the strong energy dependence to the radiation belt dynamics (b) an energy-dependent outer boundary to the inner zone that extends to higher L shells at lower energies and (c) an “S-shaped” energy-dependent inner boundary to the outer zone that results from the competition between diffusive radial transport and losses. We find that the characteristic energy-dependent structure of the radiation belts and slot region is dynamic and can be formed gradually in ~15 days, although the “S shape” can also be reproduced by assuming equilibrium conditions. The highest-energy electrons (E > 300 keV) of the inner region of the outer belt (L ~ 4–5) also constantly decay, demonstrating that hiss wave scattering affects the outer belt during times of extended plasmasphere. Through these simulations, we explain the full structure in energy and L shell of the belts and the slot formation by hiss scattering during storm recovery. We show the power and complexity of looking dynamically at the effects over all energies and L shells and the need for using data-driven and event-specific conditions.},
doi = {10.1002/2016GL068869},
journal = {Geophysical Research Letters},
number = 11,
volume = 43,
place = {United States},
year = 2016,
month = 6
}

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  • Results obtained from the electron detector on Telstar between July l0 and 31, 1962, are presented. The principal sensitivity of the detector is to electrons of energies between 0.25 and 1.0 Mev. Flux maps have been drawn for days tional electron fluxes of approximately 10⁹/cm² sec were encountered with energies in excess of 200 kev near the magnetic equator at L's of about 1.25 and 1.8R. The intensity decreased exponentially with a time constant of about 4.5 days between L values of 2.2 and 3.0 and with a time constant of about 15 days at L = 2.0 and 3.5,more » creating a slot between the inner and outer electron belts that had become pronounced by the end of July. The energy spectrum encountered seems to contain a substantial number of electrons with energies of about a Mev or more and is not inconsistent with the fission BETA spectrum above 400 kev. At lower energies the spectrum is steeper. Within the sensitivity of the measurement no spectral changes with either position or time were observed. Because of Telstar's launch date it is not possible to conclude what fraction of the electrons measured were produced by the high- altitude nuclear test of July 9. In spite of the high flux of electrons encountered, electrons are not the major source of radiation damage to the Telstar solar power plant. (auth)« less
  • The radial and local diffusion processes induced by various plasma waves govern the highly energetic electron dynamics in the Earth's radiation belts, causing distinct characteristics in electron distributions at various energies. In this study, we present our simulation results of the energetic electron evolution during a geomagnetic storm using the University of California, Los Angeles 3-D diffusion code. Following the plasma sheet electron injections, the electrons at different energy bands detected by the Magnetic Electron Ion Spectrometer (MagEIS) and Relativistic Electron Proton Telescope (REPT) instruments on board the Van Allen Probes exhibit a rapid enhancement followed by a slow diffusivemore » movement in differential energy fluxes, and the radial extent to which electrons can penetrate into depends on energy with closer penetration toward the Earth at lower energies than higher energies. We incorporate radial diffusion, local acceleration, and loss processes due to whistler mode wave observations to perform a 3-D diffusion simulation. Here, our simulation results demonstrate that chorus waves cause electron flux increase by more than 1 order of magnitude during the first 18 h, and the subsequent radial extents of the energetic electrons during the storm recovery phase are determined by the coupled radial diffusion and the pitch angle scattering by EMIC waves and plasmaspheric hiss. The radial diffusion caused by ULF waves and local plasma wave scattering are energy dependent, which lead to the observed electron flux variations with energy dependences. Lastly, this study suggests that plasma wave distributions in the inner magnetosphere are crucial for the energy-dependent intrusions of several hundred keV to several MeV electrons.« less