Analytic expressions for ULF wave radiation belt radial diffusion coefficients

TitleAnalytic expressions for ULF wave radiation belt radial diffusion coefficients
Publication TypeJournal Article
Year of Publication2014
AuthorsOzeke, LG, Mann, IR, Murphy, KR, I. Rae, J, Milling, DK
JournalJournal of Geophysical Research: Space Physics
Volume119
Issue3
Pagination1587 - 1605
Date Published03/2014
KeywordsDiffusion Coefficient; Radiation belt; ULF wave
AbstractWe present analytic expressions for ULF wave-derived radiation belt radial diffusion coefficients, as a function of L and Kp, which can easily be incorporated into global radiation belt transport models. The diffusion coefficients are derived from statistical representations of ULF wave power, electric field power mapped from ground magnetometer data, and compressional magnetic field power from in situ measurements. We show that the overall electric and magnetic diffusion coefficients are to a good approximation both independent of energy. We present example 1-D radial diffusion results from simulations driven by CRRES-observed time-dependent energy spectra at the outer boundary, under the action of radial diffusion driven by the new ULF wave radial diffusion coefficients and with empirical chorus wave loss terms (as a function of energy, Kp and L). There is excellent agreement between the differential flux produced by the 1-D, Kp-driven, radial diffusion model and CRRES observations of differential electron flux at 0.976 MeV—even though the model does not include the effects of local internal acceleration sources. Our results highlight not only the importance of correct specification of radial diffusion coefficients for developing accurate models but also show significant promise for belt specification based on relatively simple models driven by solar wind parameters such as solar wind speed or geomagnetic indices such as Kp.
URLhttp://doi.wiley.com/10.1002/2013JA019204
DOI10.1002/2013JA019204
Short TitleJ. Geophys. Res. Space Physics


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