Modeling a Realistic “Gradual” SEP Event within 2 AU

Coronal Mass Ejection (CME) -driven shocks, as a primary source of Solar Energetic Particles (SEP), can evolve significantly while propagating away from the Sun. Their characteristics are crucial to understand the underlying particle acceleration mechanism,considered to be the Diffusive Shock Acceleration(DSA)process. Modeling the propagation of CMEdriven shocks and the consequent DSA process is important to both space weather research and forecasting. By utilizing an improved particle acceleration and transport model,a realistic "gradual" SEP event that happened on April 18th,2014 was modelled. Four locations in the ecliptic plane within 2 Astronomical Units(AU)from the Sun,including the location of the Earth,are examined with the model. Our results show that shock geometry plays a very important role in determining the energetic particle fluxes.