1997年1月事件行星际扰动在三维背景太阳风中传播的数值模拟

NUMERICAL SIMULATION FOR PROPAGATION OF INTERPLANETARY DISTURBANCE IN THREE DIMENSIONAL SOLAR WIND BACKGROUND DURING JANUARY 1997 EVENT

利用一个三维的MHD模式 ,从数值预报的角度出发 ,以 1 997年 1月事件的有关太阳观测为依据 ,构造比较符合物理实际的边值条件 ,通过三维数值模拟得到了稳定的比较接近真实的太阳风背景场 .结果显示此次事件太阳风背景场的磁场关于赤道面不对称 ,有较明显的倾斜和扭曲 ,同时磁场较弱 ;等离子体各参量相对于事件的太阳源为东西和南北不对称结构 .本文数值模拟了磁场南北分量Bθ 的不同取法对背景场的影响 ,结果表明在源表面磁场有明显倾斜的情况下 ,内边界处磁场南北分量不宜假设为零 .在此基础上 ,初步数值研究了行星际扰动在三维背景场中的传播过程 。

Based on a three dimensional MHD model,a relatively real interplanetary solar wind background during Janurary 1997 event is obtained by using a set of initial and boundary conditions derived from some observations near the real space environment. Results show that the magnetic field at the source surface is equatorially saynmetric and is obviously tilted and wrapped. In addition,the plasma variables are asymmetric in relation to the event location. The numerical experiment for the different schemes of B θ show that under an obviously tilted current sheet, B θ can not be assumed to be zero. Based on these background results,the propagation process of disturbance is obtained. We also provide comparison with the WIND observations.