Numerical simulations of storm-time outer radiation belt dynamics by wave–particle interactions including cross diffusion

Using the recently developed hybrid finite difference (HFD) code, we solve the two-dimensional bounce-averaged Fokker–Planck equation with cross-pitch-angle-energy diffusion to evaluate the electron phase space density (PSD) evolution driven by multiple wave–particle interactions during storms. Numerical results show that PSDs of ∼MeV∼MeV electrons can be depleted by two orders of magnitude at lower pitch-angles during the main phase primarily due to pitch-angle scattering by hiss and electromagnetic ion cyclotron (EMIC) waves, and then enhance by two orders of magnitude compared with the prestorm state during the recovery phase primarily due to acceleration by chorus wave. Furthermore, the effects of the cross terms and various electromagnetic waves are also been identified.