3:30 PM - 4:30 PM
During non-storm periods, the radiation belt electron evolutions are mostly controlled by the source from radial diffusion transport and the pitch angle scattering loss by magnetospheric waves. The Van Allen Probes measurements have provided detailed description about the radiation belt evolution and structure, including the inward intrusion of several MeV electrons in the outer radiation belt and several hundred keV electrons in the slot region, the decay of the energetic electrons during their inward transport, and the ‘S-shaped’ radiation belt structure formed as a consequence of the electron decay. Our 3D radiation belt simulation including radial diffusion and pitch angle and energy diffusion by plasmaspheric hiss and Electromagnetic Ion Cyclotron (EMIC) waves reproduces the essential features of the observed electron flux evolution. The recent improvements in radial diffusion models provide reasonable estimates on the radial intrusion timescale of energetic electrons. The wave-induced electron decay timescales and pitch angle distributions in our simulation are consistent with the Van Allen Probes observations over multiple energy channels. In addition, the energy-dependent electron scattering due to plasmaspheric hiss leads to the formation of ‘S-shaped’ electron flux contours across the radiation belts. Our study quantitatively evaluates the roles of ULF waves, plasmaspheric hiss, and EMIC waves in the transport and loss of radiation belt electrons.