Quantifying Radiation Belt Losses due to Wave-Particle Interactions with Global Test Particle Simulations

Abstract:

Magnetospheric plasma waves play a significant role in radiation belt dynamics, providing both a source and loss to the radiation belt electrons through energization and precipitation driven by pitch angle scattering. Distinguishing the relative contribution of wave-particle interactions on radiation belt flux variations remains observationally challenging as they often occur in conjunction with other important acceleration and loss mechanisms. Numerical simulations are in a unique position to address this question; however, this requires a first-principles model that includes both realistic dynamic global magnetic field and microscopic wave-particle interactions. In this work, we incorporate electron gyroresonance with parallel propagating whistler modes into our three-dimensional, test particle model, CHIMP. Pitch-angle scattering and energization of the test particles are derived from an analytical expression for the quasi-linear diffusion coefficient and resonant diffusion curves. The global, dynamic electromagnetic fields are generated from our newly-developed global magnetosphere model, GAMERA, coupled to the Rice Convection Model. GAMERA is a sophisticated reinvention of the LFM model capable of resolving crucial mesoscale features needed to accurately model storm-time dynamics. We will quantify the impact of wave-particle interactions on the outer belt electron losses and discuss their relative importance with magnetopause losses under geomagnetic storm conditions through direct comparisons when resonant interactions are not included.