Title

Evolution and slow decay of an unusual narrow ring of relativistic electrons near L~ 3.2 following the September 2012 magnetic storm

Abstract

[1] A quantitative analysis is performed on the decay of an unusual ring of relativistic electrons between 3 and 3.5 RE, which was observed by the Relativistic Electron Proton Telescope instrument on the Van Allen probes. The ring formed on 3 September 2012 during the main phase of a magnetic storm due to the partial depletion of the outer radiation belt for L > 3.5, and this remnant belt of relativistic electrons persisted at energies above 2 MeV, exhibiting only slow decay, until it was finally destroyed during another magnetic storm on 1 October. This long-term stability of the relativistic electron ring was associated with the rapid outward migration and maintenance of the plasmapause to distances greater than L = 4. The remnant ring was thus immune from the dynamic process, which caused rapid rebuilding of the outer radiation belt at L > 4, and was only subject to slow decay due to pitch angle scattering by plasmaspheric hiss on timescales exceeding 10–20 days for electron energies above 3 MeV. At lower energies, the decay is much more rapid, consistent with the absence of a long-duration electron ring at energies below 2 MeV.

Department

Physics

Publication Date

6-1-2013

Journal Title

Geophysical Research Letters

Publisher

American Geophysical Union

Digital Object Identifier (DOI)

10.1002/grl.50627

Document Type

Article

Rights

©2013. American Geophysical Union. All Rights Reserved.

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