Simulation of the energy dependent electron diffusion processes in the Earth’s outer radiation belt

Abstract:

The radial and local diffusion processes induced by various plasma waves govern the highly energetic electron dynamics in the Earth’s radiation belts, and cause the distinct characteristics in electron distributions at various energies. In this study, we present our recent simulation results of the energetic electron evolution during a geomagnetic storm using the UCLA 3D diffusion code. Following the plasmasheet electron injections and the subsequent acceleration, the electrons at different energies detected by MagEIS and REPT instruments onboard the Van Allen probes present rapid enhancement and slow decay in differential energy fluxes, and radial extension over different L-shells. The radial transport by ULF waves and local scattering by whistler-mode plasma waves and EMIC waves are energy dependent and may account for the observed different behaviors of hundreds keV to several MeV electrons. We incorporate radial diffusion and local acceleration and loss processes due to real-time whistler-mode wave observations to perform a 3D diffusion simulation. Our simulation results present the roles of each wave mode and the major controlling factors for the electron evolution with different energies.