Title: Radiation belt electron acceleration during the 17 March 2015 geomagnetic storm: Observations and simulations

Abstract

Various physical processes are known to cause acceleration, loss, and transport of energetic electrons in the Earth's radiation belts, but their quantitative roles in different time and space need further investigation. During the largest storm over the past decade (17 March 2015), relativistic electrons experienced fairly rapid acceleration up to ~7 MeV within 2 days after an initial substantial dropout, as observed by Van Allen Probes. In the present paper, we evaluate the relative roles of various physical processes during the recovery phase of this large storm using a 3-D diffusion simulation. By quantitatively comparing the observed and simulated electron evolution, we found that chorus plays a critical role in accelerating electrons up to several MeV near the developing peak location and produces characteristic flat-top pitch angle distributions. By only including radial diffusion, the simulation underestimates the observed electron acceleration, while radial diffusion plays an important role in redistributing electrons and potentially accelerates them to even higher energies. Moreover, plasmaspheric hiss is found to provide efficient pitch angle scattering losses for hundreds of keV electrons, while its scattering effect on > 1 MeV electrons is relatively slow. Although an additional loss process is required to fully explain the overestimated electronmore » fluxes at multi-MeV, the combined physical processes of radial diffusion and pitch angle and energy diffusion by chorus and hiss reproduce the observed electron dynamics remarkably well, suggesting that quasi-linear diffusion theory is reasonable to evaluate radiation belt electron dynamics during this big storm.« less

Authors:

Li, W. ^[1]; Ma, Q.  ^[1];

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Thorne, R. M. ^[1]; Bortnik, J. ^[1]; Zhang, X. -J. ^[2]; Li, J. ^[1]; Baker, D. N. ^[3]; Reeves, Geoffrey D.  ^[4];

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Spence, H. E. ^[5]; Kletzing, C. A. ^[6]; Kurth, W. S. ^[6]; Hospodarsky, G. B. ^[6]; Blake, J. B. ^[7]; Fennell, J. F. ^[7]; Kanekal, S. G. ^[8]; Angelopoulos, V. ^[9]; Green, J. C. ^[10]; Goldstein, J. ^[11]

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+ Show Author Affiliations

1. Univ. of California, Los Angeles, CA (United States). Dept. of Atmospheric and Oceanic Sciences
2. Univ. of California, Los Angeles, CA (United States). Dept. of Atmospheric and Oceanic Sciences; Univ. of California, Los Angeles, CA (United States). Inst. of Geophysics and Planetary Physics / Earth, Planetary and Space Sciences
3. Univ. of Colorado, Boulder, CO (United States). Lab. for Atmospheric and Space Research
4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
5. Univ. of New Hampshire, Durham, NH (United States). Inst. for the Study of Earth, Oceans, and Space
6. Univ. of Iowa, Iowa City, IA (United States). Dept. of Physics and Astronomy
7. Aerospace Corporation, Los Angeles, CA (United States)
8. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
9. Univ. of California, Los Angeles, CA (United States). Inst. of Geophysics and Planetary Physics / Earth, Planetary and Space Sciences
10. Space Hazard Applications, Golden, CO (United States)
11. Southwest Research Inst. (SwRI), San Antonio, TX (United States). Space Science and Engineering Division; Univ. of Texas, San Antonio, TX (United States). Dept. of Physics and Astronomy

Publication Date:

2016-06-10

Research Org.:

Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

National Aeronautic and Space Administration (NASA); National Science Foundation (NSF); USDOE

OSTI Identifier:

1402604

Report Number(s):

LA-UR-16-20486
Journal ID: ISSN 2169-9380; TRN: US1703003

Grant/Contract Number:  

AC52-06NA25396; 967399; 921647; NAS5-01072; FA9550-15-1-0158; NNX15AI96G; NNX15AF61G; NNX11AR64G; NNX13AI61G; NNX14AI18G; AGS 1405054; 1564510

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Space Physics

Additional Journal Information:

Journal Volume: 121; Journal Issue: 6; Journal ID: ISSN 2169-9380

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 58 GEOSCIENCES; Heliospheric and Magnetospheric Physics; electron acceleration; chorus-driven local acceleration; radial diffusion