RAM - C P L Simulations of Electron Transport and Plasma Wave Scattering Using Van Allen Probes Data

Abstract:

The high variability of energetic electron fluxes in the inner magnetosphere remains inadequately explained due to their complex dynamics including competing particle acceleration and loss processes. We study the combined effects from scattering by chorus and EMIC waves and radial transport on ring current and radiation belt dynamics. We use our ring current-atmosphere interactions model that solves the kinetic equation for H⁺, O⁺, and He⁺ ions and electrons and is coupled with a time-dependent 2-D plasmasphere model (RAM-CPL). The plasma boundary conditions are specified from LANL geosynchronous observations. We simulate wave-particle interactions on a global scale as particles drift around the Earth using L and MLT-dependent event-specific chorus and EMIC wave models. The precipitating electron fluxes measured by multiple NOAA satellites are fitted to the equatorial wave measurements made by the EMFISIS instrument on the Van Allen Probes to infer the chorus wave amplitudes on a global scale. The fast dropout of the radiation belts during the October 2012 “double-dip” storm event is investigated and the role of various processes such as outward radial diffusion combined with magnetopause shadowing and enhanced electron precipitation into the atmosphere is evaluated. The simulated cold plasma densities are compared with in situ EMFISIS observations along the Van Allen Probes’ orbits showing good agreement.