The Parameterization of Wave-Particle Interactions in the Outer Radiation Belt

Abstract:

We explore the use of mean value empirical wave models in diffusion models of the Outer Radiation Belt. We show that magnetospheric wave power is not normally distributed in time and that geomagnetic activity does not provide a deterministic proxy for the temporal variability of wave activity. Our findings indicate that current diffusion models may significantly overestimate the action of wave-particle interactions due to extremely low frequency and very low frequency waves in the magnetosphere. We demonstrate using simple diffusion models how the subgrid parameterization may be improved by adopting a stochastic, rather than deterministic, description of diffusion across all wave-particle interactions, from ultra-low frequency waves to very low frequency waves. We discuss the number of degrees of freedom of the parameterizations for a range of different wave-particle interactions and suggest a range of algorithms developed in other fields that could be successfully implemented in diffusion-based models.