Simulation of ${}^3$He rich solar energetic particle events observed by multi-spacecraft at different longitude

Abstract:

The ${}^3$He rich Solar Energetic Particle (SEP) events are usually considered to be produced by the solar flares. Recently, observation results from different spacecraft, e.g., the STEREO A and B, and ACE, show that some ${}^3$He rich events can cover a very wide longitudinal extent, which is much larger than the area of solar flare. It means that SEPs can be observed on the field lines disconnected far away from the source. For interpreting this phenomenon, SEPs should propagate in the solar atmosphere or cross interplanetary magnetic field (IMF) by the effect of perpendicular diffusion. In this work, a Fokker-Planck focus transport equation in three-dimensional Parker IMF is solved numerically. The effects of solar atmosphere propagation and perpendicular diffusion are included in our model, and we compare the simulation results with multi-spacecraft observed at different longitude. By this way, we investigate the transport process of SEPs, and find out the mechanism that led to the wide spread SEP events.