Recent developments in the radiation belt environment model

The fluxes of energetic particles in the radiation belts are found to be strongly controlled by the solar wind conditions. In order to understand and predict the radiation particle intensities, we have developed a physics-based Radiation Belt Environment (RBE) model that considers the influences from the solar wind, ring current and plasmasphere. Recently, an improved calculation of wave-particle interactions has been incorporated. In particular, the model now includes cross diffusion in energy and pitch-angle. We find that the exclusion of cross diffusion could cause significant overestimation of electron flux enhancement during storm recovery. The RBE model is also connected to MHD fields so that the response of the radiation belts to fast variations in the global magnetosphere can be studied. We are able to reproduce the rapid flux increase during a substorm dipolarization on 4 September 2008. The timing is much shorter than the time scale of wave associated acceleration.

Research Highlights
► A radiation belt environment model has been established to calculate and predict the energetic particle fluxes in the Earth's radiation belts.
► A comprehensive treatment of wave-particle interactions is implemented in the radiation belt environment model, including particle cross diffusion in energy and pitch-angle.
► Particle transport in the radiation belt environment model is driven by the fields output from global magnetohydrodynamics (MHD) models. Therefore, particle transport or radial diffusion due to low-frequency MHD waves and inductive electric fields associated with magnetic reconfiguration are well represented in the radiation belt model.