Driving Earth's Outer Radiation Belt With Alfvénic Turbulence

Semi-empirical coefficients for electron transport in Alfv & eacute;nic turbulence are used to drive the global evolution of energetic electron distributions through Earth's outer radiation belt. It is shown how these turbulent fields facilitate radial transport and pitch-angle scattering that drive losses through the magnetopause, into the plasma sheet, through the plasmapause and to the atmosphere. Butterfly distributions are formed due to pitch-angle scattering and the combined effect of the loss processes. For the observed spectrum of oscillations, it is estimated that Alfv & eacute;nic turbulence drives order of magnitude depletions of outer radiation belt electron fluxes at relativistic energies over a period of a few hours. On the other hand, at lower energies, energization in transverse Alfv & eacute;nic electric fields leads to enhancements of the electron spectrum to provide a source population for subsequent acceleration to higher energies and, in concert with the loss processes, provides exponential spectral form as a function of energy.