Subjects: Geosciences >> Space Physics submitted time 2016-05-13
Abstract： Solar energetic particle (SEP) can destroy the spacecraft, and has great influence on human activities. Thus, it is of importance to forecast SEP events. SEP events can be divided by three general categories: impulsive SEP events, gradual SEP events and mixed SEP events. Impulsive SEP events, with characteristics of low intensity, short duration, and enhanced He-3, are correlated to solar flares. Gradual SEP events which become the main simulation branch of current research are related to coronal mass ejections (CMEs) and they usually have high flux in protons and last longer. Mixed SEP events maintain complex features of the former two kinds of events. Several theories and numerical models are applied to simulate gradual SEP events. Each model makes some assumptions to simplify the complex acceleration and transportation processes. No research to date has combined accurate shock evolution, particles injection and acceleration, with their interplanetary transport. In order to develop the physics-based SEP prediction model and improve the ability to forecast SEP events, it is necessary to self-consistently combine the magnetohydrodynamic (MHD) model that describes CME-driven shock propagation with particle model that simulates the acceleration and transportation processes of particles. In this paper, firstly, we review current models, which have been used to describe gradual SEP events and their applications. Generally, there are two major approaches to model gradual SEP events: some studies include the acceleration mechanisms of SEPs induced by CME-driven shocks, while others assume a fixed particle injecting source at the shock. In addition, some researchers also consider the effects of perpendicular diffusion on SEPs propagation in three-dimensional interplanetary magnetic fields. These models can partially reproduce the observed properties for SEP events. Then, we make a brief review of numerical MHD simulation models, such as Space Weather Modeling Frame (SWMF), CORonal and HELiospheric (CORHEL) model, Solar InterPlanetary-Conservative Element Solution Element (SIP-CESE) model, COronal INterplanetary (COIN) model. All these models can be used to workout the propagation parameters of CME and CME-driven shocks, which are expected to provide inputs to the particle model. Finally, some discussions of the future work about how to combine MHD and particle models are presented.
Peer Review Status:
Awaiting Review
Hits
Hits
Downloads
Comment