Title: Prompt acceleration of magnetospheric electrons to ultrarelativistic energies by the 17 March 2015 interplanetary shock

Abstract

Trapped electrons in Earth's outer Van Allen radiation belt are influenced profoundly by solar phenomena such as high-speed solar wind streams, coronal mass ejections (CME), and interplanetary (IP) shocks. In particular, strong IP shocks compress the magnetosphere suddenly and result in rapid energization of electrons within minutes. It is believed that the electric fields induced by the rapid change in the geomagnetic field are responsible for the energization. During the latter part of March 2015, a CME impact led to the most powerful geomagnetic storm (minimum Dst = -223 nT at 17 March, 23 UT) observed not only during the Van Allen Probe era but also the entire preceding decade. Magnetospheric response in the outer radiation belt eventually resulted in elevated levels of energized electrons. The CME itself was preceded by a strong IP shock whose immediate effects vis-a-vis electron energization were observed by sensors on board the Van Allen Probes. The comprehensive and high-quality data from the Van Allen Probes enable the determination of the location of the electron injection, timescales, and spectral aspects of the energized electrons. The observations clearly show that ultrarelativistic electrons with energies E > 6 MeV were injected deep into the magnetosphere at Lmore » ≈ 3 within about 2 min of the shock impact. However, electrons in the energy range of ≈250 keV to ≈900 keV showed no immediate response to the IP shock. Finally, electric and magnetic fields resulting from the shock-driven compression complete the comprehensive set of observations that provide a full description of the near-instantaneous electron energization.« less

Authors:

Kanekal, S. G. ^[1]; Baker, D. N. ^[2]; Fennell, J. F. ^[3]; Jones, A. ^[4]; Schiller, Q. ^[1]; Richardson, I. G. ^[5]; Li, X. ^[1]; Turner, D. L. ^[6]; Califf, S. ^[2]; Claudepierre, S. G. ^[6]; Wilson, L. B. ^[1]; Jaynes, A. ^[2]; Blake, J. B. ^[6]; Reeves, G. D.  ^[7];

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Spence, H. E. ^[8]; Kletzing, C. A. ^[9]; Wygant, J. R. ^[10]

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+ Show Author Affiliations

1. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
2. Univ. of Colorado, Boulder, CO (United States). Lab. for Atmospheric and Space Physics
3. Aerospace Corporation, Los Angeles, CA (United States); NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
4. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); The Catholic Univ. of America, Washington, DC (United States). Physics Dept.
5. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. of Maryland, College Park, MD (United States). CRESST/Dept. of Astronomy
6. Aerospace Corporation, Los Angeles, CA (United States)
7. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
8. Univ. of New Hampshire, Durham, NH (United States). Inst. for Study of Earth, Oceans, and Space
9. Univ. of Iowa, Iowa City, IA (United States). Dept. of Physics and Astronomy
10. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Physics and Astronomy

Publication Date:

Mon Aug 15 00:00:00 EDT 2016

Research Org.:

Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

National Aeronautics and Space Administration (NASA)

OSTI Identifier:

1499330

Report Number(s):

LA-UR-16-22085
Journal ID: ISSN 2169-9380

Grant/Contract Number:  

89233218CNA000001

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Space Physics

Additional Journal Information:

Journal Volume: 121; Journal Issue: 8; Journal ID: ISSN 2169-9380

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; Heliospheric and Magnetospheric Physics