PARASOL: A novel simulation model for forecasting solar energetic particle events

Gradual solar energetic particle (SEP) events are attributed to particle acceleration in shock waves driven by coronal mass ejections (CMEs). These events have significant space-weather effects, prompting ongoing efforts to develop models capable of forecasting their characteristics. Here we present a new such model, PARASOL. PARASOL is an extension of the PArticle Radiation Asset Directed at Interplanetary Space Exploration (PARADISE) test-particle simulation model of SEP transport. Its key feature is a semi-analytical description of the inner foreshock region (near the shock), constructed using simulations from the SOLar Particle Acceleration in Coronal Shocks (SOLPACS) model, which simulates proton acceleration self-consistently coupled with Alfvén wave generation upstream of the shock. PARASOL requires magnetohydrodynamic (MHD) parameters of the solar wind and the shock as inputs. To evaluate the PARASOL performance, we simulated the 12 July 2012 SEP event using the EUropean Heliospheric FORecasting Information Asset (EUHFORIA) MHD simulation of the solar wind and CME for this event. The PARASOL simulation successfully reproduced the observed energetic storm particle (ESP) event near the shock, achieving an intensity within one order of magnitude of the observations.