Publication Date:
2013-06-07
Description:
[1] A quantitative analysis is performed on the decay of an unusual ring of relativistic electrons between 3 and 3.5 R E , which was observed by the REPT instrument on the Van Allen Probes. The ring formed on September 3, 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 October 1. 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.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics
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