Reproducing Ultra‐Relativistic Electron Acceleration Using a Coupled Density and Radiation Belt Model.

The cold plasma density can significantly alter the rate of diffusion of radiation belt electrons by chorus waves within the magnetosphere, and the range of energies at which diffusion is effective. We describe a coupled density and radiation belt model based on the British Antarctic Survey Radiation Belt Model that uses spatially and temporally varying values of fpe/fce ${f}_{pe}/{f}_{ce}$ to drive a statistical model of electron diffusion due to chorus waves. We demonstrate that this approach of including the variance in fpe/fce ${f}_{pe}/{f}_{ce}$ recreates the acceleration of electrons up to MeV energies better than other previous approaches to including fpe/fce ${f}_{pe}/{f}_{ce}$. Plain Language Summary: The density of low energy charged particles trapped in Earth's magnetic field can influence how higher energy trapped electrons are affected by natural radio waves within the magnetic field. We describe a modification of the British Antarctic Survey Radiation Belt Model that includes a model of density that varies in both time and space. These density values are used to drive a statistical model of electron scattering due to chorus waves. We demonstrate that including the variance of density in the model recreates the acceleration of electrons up to ultra‐relativistic energies better than other previous approaches to accounting for the low energy charged particle density. Key Points: More realistic information about the plasma density leads to better recreations of multi‐MeV electron flux enhancements in a diffusion modelChorus waves can directly accelerate electrons to multi‐MeV energies at L* = 4 when the plasma density is low, without radial diffusionThe Van Allen Probes fpe/fce ${f}_{pe}/{f}_{ce}$ measurements are biased away from values less than 2.5 [ABSTRACT FROM AUTHOR]