Ultra-relativistic radiation belt extinction and ULF wave radial diffusion: Modeling the September 2014 extended dropout event

TitleUltra-relativistic radiation belt extinction and ULF wave radial diffusion: Modeling the September 2014 extended dropout event
Publication TypeJournal Article
Year of Publication2017
AuthorsOzeke, LG, Mann, IR, Murphy, KR, Sibeck, DG, Baker, DN
JournalGeophysical Research Letters
Date Published03/2017
Keywordsradial diffusion; Radiation belt; ULF waves; ultrarelativistic; Van Allen Probes; wave-particle interactions
AbstractIn September 2014 an unusually long-lasting (≳10 days) ultra-relativistic electron flux depletion occurred in the outer radiation belt despite ongoing solar wind forcing. We simulate this period using a ULF wave radial diffusion model, driven by observed ULF wave power coupled to flux variations at the outer boundary at L* = 5, including empirical electron loss models due to chorus and hiss wave scattering. Our results show that unexplained rapid main phase loss, that depletes the belt within hours, is essential to explain the observations. Such ultra-relativistic electron extinction decouples the prestorm and poststorm fluxes, revealing the subsequent belt dynamics to be surprisingly independent of prestorm flux. However, once this extinction is included, ULF wave transport and coupling to the outer boundary explain the extended depletion event and also the eventual flux recovery. Neither local acceleration nor ongoing losses from hiss or chorus wave scattering to the atmosphere are required.
URLhttp://doi.wiley.com/10.1002/2017GL072811
DOI10.1002/2017GL072811
Short TitleGeophys. Res. Lett.


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