Speaker
Description
We report a recent modeling study of the global propagation of solar energetic particle (SEP) fluxes between 30 solar radii and 1 au for impulsive events. We utilize a modified and expanded version of the EPREM model for global particle transport, coupled with an observation-driven solar wind description from the MAS heliospheric MHD solution. A power law distribution of protons with a sharp temporal profile approximating an impulsive event and spatial extent on the order of a large active region is injected at the inner boundary of the model, which coincides with the MHD model's inner boundary. We study the evolution of the proton flux distribution out to 1.2 au in energies between 1-100 MeV over the course of multiple days from the injection time. We vary the pitch angle distribution at the source to study the effects of first-order pitch anisotropy of the injected flux; we also vary the prescribed amount of perpendicular diffusion. The results provide a detailed look at the effects of impulsive SEP propagation in a realistic MHD environment. They demonstrate the spatially anisotropic nature of diffusion of SEPs in the inner heliosphere, and shed light on the possible influence of persistent solar wind structures on forming and retaining energetic particle reservoirs.
