Competing source and loss mechanisms due to wave-particle interactions in Earth’s outer radiation belt during the 30 September to 3 October 2012 geomagnetic storm

Authors

D. L. Turner, University of California - Los AngelesFollow
V. Angelopoulos, University of California - Los AngelesFollow
W. Li, University of California - Los Angeles
J. Bortnik, University of California - Los AngelesFollow
B. Ni, University of California - Los AngelesFollow
Q. Ma, University of California - Los Angeles
R. M. Thorne, University of California - Los AngelesFollow
S. K. Morley, Los Alamos National LaboratoryFollow
M. G. Henderson, Los Alamos National LaboratoryFollow
Geoffrey Reeves, Los Alamos National LaboratoryFollow
M. Usanova, University of Alberta
I. R. Mann, University of AlbertaFollow
S. Claudepierre, Aerospace CorporationFollow
J. B. Blake, Aerospace CorporationFollow
D. N. Baker, University of Colorado BoulderFollow
Chia-Lin L. Huang, University of New Hampshire - Main CampusFollow
Harlan E. Spence, University of New HampshireFollow
W. S. Kurth, University of IowaFollow
C A. Kletzing, University of IowaFollow
J. V. Rodriguez, University of Colorado Boulder

Abstract

Abstract Drastic variations of Earth’s outer radiation belt electrons ultimately result from various competing source, loss, and transport processes, to which wave-particle interactions are critically important. Using 15 spacecraft including NASA’s Van Allen Probes, THEMIS, and SAMPEX missions and NOAA’s GOES and POES constellations, we investigated the evolution of the outer belt during the strong geomagnetic storm of 30 September to 3 October 2012. This storm’s main phase dropout exhibited enhanced losses to the atmosphere at L*< 4, where the phase space density (PSD) of multi-MeV electrons dropped by over an order of magnitude in1 MeV electrons and energetic protons, SAMPEX >1 MeV electrons, and ground observations of band-limited Pc1-2 wave activity, we show that this sudden loss was consistent with pitch angle scattering by electromagnetic ion cyclotron waves in the dusk magnetic local time sector at 3< L*< 4. At 4< L*< 5, local acceleration was also active during the main and early recovery phases, when growing peaks in electron PSD were observed by both Van Allen Probes and THEMIS. This acceleration corresponded to the period when IMF Bz was southward, the AE index was >300 nT, and energetic electron injections and whistler-mode chorus waves were observed throughout the inner magnetosphere for >12 h. After this period, Bz turned northward, and injections, chorus activity, and enhancements in PSD ceased. Overall, the outer belt was depleted by this storm. From the unprecedented level of observations available, we show direct evidence of the competitive nature of different wave-particle interactions controlling relativistic electron fluxes in the outer radiation belt.

Department

Physics

Publication Date

3-2014

Journal Title

Journal of Geophysical Research: Space Physics

Publisher

American Geophysical Union Publications

Digital Object Identifier (DOI)

10.1002/2014JA019770

Document Type

Article

Recommended Citation

Turner, D. L., et al. (2014), Competing source and loss mechanisms due to wave-particle interactions in Earth’s outer radiation belt during the 30 September to 3 October 2012 geomagnetic storm, J. Geophys. Res. Space Physics, 119, 1960–1979, doi:10.1002/ 2014JA019770.

Rights

©2014. American Geophysical Union. All Rights Reserved.