不同内边界条件下SEP事件实例的集合数值模拟及其在SEP事件预报中的应用

Ensemble numerical simulations of a realistic SEP event under conditions of various inner boundaries and the application in SEP forecast

太阳高能粒子(SEP)事件的定量数值预报是空间态势感知的重要方面之一。SEP事件主要来自于日冕物质抛射(CME)所驱动的激波扩散加速(DSA)。文章在三个有关模型的基础上,结合1 AU处卫星的太阳风观测参数和日冕仪的CME观测参数,建立了一套可用于预报SEP事件的数值方法。利用该方法对一次SEP实例进行数值模拟,并将模拟结果与GOES卫星观测结果进行比较。结果表明:数值模拟得到的>10 MeV的高能粒子的通量和观测较为吻合,>100 MeV的高能粒子的通量高于观测值。针对此事件进一步开展了不同CME抛射速度和不同内边界背景太阳风温度条件下的集合模拟试验,结果表明:CME抛射速度对SEP事件中高能粒子通量和能谱影响较大,而内边界背景太阳风温度的改变对于高能粒子通量和能谱的影响几乎可以忽略不计。

It is an important part of the space environmental situation awareness to forecast the solar energetic particle(SEP)events quantitatively.Generally,the high energy particles in most major SEP events originate in the front area of the shocks driven by the coronal mass ejection(CME)and are accelerated by a machamism of the diffusive shock acceleration(DSA).In this paper,an SEP forecast toolset is developed on the basis of three specified models,and the solar wind observation parameters of the satellite at the 1 AU and the CME observation parameters of the coronagraph.The parameters of a realistic SEP event is simulated and compared with the GOES spacecraft observations.It is shown that the simulated flux of the particles of more than 10 MeV fits the observation well,while the simulated flux of the particles of more than 100 MeV is a little higher than the observed result.Furthermore,we have conducted the ensemble numerical simulations over the particular event and investigated the effects of different CME speeds as well as the background solar wind temperatures at the inner boundary on the SEP events.The results show that the CME speed plays a very important role in determining the particle flux and the power spectrum,while the effect of the background solar wind temperature is negligible.