Ensemble transport modelling of solar energetic particle events

Variations in the acceleration and transport conditions may account for the large inter-event variation noticed in observed solar energetic particle (SEP) events. As an initial attempt to quantify this variability, we examine the sensitivity of the solutions from a 2D SEP transport model to different initializations. An ensemble modeling approach is used to initiate the model with different input parameters, related to the acceleration and transport of these particles. We show that, at Earth’s position, seemingly small changes in the acceleration and transport parameters can lead to significant variations in the SEP peak intensity, onset delay, and peak delay. We posit that this might explain much of the observed SEP variability. While the methodology used in this work is a basic, first proof-of-concept, approach, we suggest that a similar, but refined, approach might be a viable method that could even be implemented in (near) real-time physics-based predictive models to illustrate the associated uncertainty in simulation results.