Modeling of Time Profiles of Solar Energetic Particle Events

Abstract

Solar energetic particle (SEP) events are mostly generated by solar flares. They can be associated not only with flares that occur on the visible side of the Sun but also on the backside. It is noted that the shape of the time profiles of SEP events associated with flares on the back side of the Sun does not correspond to the typical impulsive or gradual time profiles. X-rays are the main source of information about the processes of energy release and particle acceleration in solar flares. For many years, information on this type of emission for flares on the back side of the Sun was rare. Nowadays, the ability to obtain this type of information is becoming more and more available. We present the results of testing numerical model realized as a code that makes it possible to reproduce the shape of the time profile of SEP events using simple assumptions about particle propagation into the interplanetary space. The time profiles of SEP protons with energies above 30 MeV have been modeled assuming that the particles were accelerated only in the solar atmosphere during the flare. Tests have been done for four impulsive flares that occurred in the western hemisphere of the Sun and in the center of the solar disk. We simulated the time profile of an SEP event, the source of which was a flare that possibly occurred on the backside of the Sun on October 21, 2003. The results, possibilities for model improvements, and the application of this method to the study of SEP events with no source on the visible side of the Sun are discussed.