Speaker
Dr
Louis Ozeke
(University of Alberta)
Description
We 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 electric field power, mapped from ground-magnetometer data, and from in-situ characterisations of compressional magnetic field power. We show that the overall electric and magnetic diffusion coefficients are to a good approximation both independent of energy and the azimuthal wavenumber, m, of the waves. We present example 1-D radial diffusion results from simulations driven by THEMIS and 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 an empirical VLF lower band chorus loss term (as a function of Kp and L) The model results are seen to be in excellent agreement with THEMIS and CRRES flux observations - even though the model does not include the effects of a local internal acceleration source such as might be expected to arise from resonance with lower band chorus waves. Our results highlight not only the importance of correct specification of radial diffusion coefficients for developing accurate models, but also show significant promise for radiation belt specification based on relatively simple models driven by solar wind parameters such as solar wind speed or geomagnetic indices such as Kp.
Primary author
Dr
Louis Ozeke
(University of Alberta)
Co-authors
Dr
Alex Degeling
(University of Alberta)
Dr
Drew Turner
(University of California, Los Angeles)
Prof.
Iain Jonathan Rae
(Mullard Space Science Laboratory)
Prof.
Ian Mann
(University of Alberta)
Mr
Kyle Murphy
(University of Alberta)
