Nonlinear Dynamics of Radiation Belt Electrons Interacting With Chorus Emissions Localized in Longitude

Using results of test particle simulations of electrons interacting with whistler mode chorus emissions, we numerically obtain Green's functions to model evolution of the electron distribution function after all of the possible interactions with the waves. In both wave models with and without subpackets, electrons undergoing the cyclotron resonance with the waves are efficiently accelerated by nonlinear wave trapping. Since the strong modulation of the wave amplitude (in the case of the waves with subpackets) affects dynamics of resonant electrons, the electrons are detrapped from the wave potential or entrapped into it more frequently than those interacting with the waves without subpackets. As a result of interaction with the waves with subpackets, the number of electrons undergoing the acceleration is increased, while the acceleration efficiency in energy is decreased because of shorter interaction time. Modifying the numerical Green's function method with the simplified model of chorus waves uniform in longitude (Omura et al., 2015, https://doi.org/10.1002/2015JA021563), we compute the formation process of the outer radiation belt electron fluxes induced by the interaction with the chorus waves localized in longitude occurring for a time scale of 1 hr. The formation of MeV electron fluxes is characterized by large acceleration rates and butterfly pitch angle distributions, which are found in satellite observation results.