子午面磁层顶位形结构的MHD模拟研究

本文基于太阳风-磁层-电离层耦合的全球磁流体力学(MHD)数值模拟,研究几种典型的太阳风动压和行星际磁场条件下,地球子午面上方磁层顶的位置和形状特征,以及磁层顶位形参数日下点距离和磁层顶张角随行星际条件的变化规律。模拟结果表明:正午午夜子午面磁层顶位形具有内凹结构,当行星际磁场为南向时,随磁场强度增强,日下点距离减小;行星际磁场为北向时,随磁场强度增强,日下点距离增大。动压增大,日下点距离减小。南向磁场强度增强,磁层顶张角变大。这些模拟结果与基于卫星数据的高纬经验模型(B00)以及(Schield)模型的经验结论相吻合,说明MHD模拟是研究磁层顶位形的有效工具。特别是在高纬穿越数据的获得受限时,基于对磁层顶位形的物理理论研究构建的数值模拟数据是解决这一问题的有效途径。

An MHD Simulation Study on the Location and Shape of Magnetopause in Meridian Plane

Based on the Solar wind-Magnetosphere-Ionosphere coupling global MHD simulation,the position and shape of the noon midnight meridian plane magnetopause under several solar wind dynamic pressure and interplanetary magnetic field(IMF) conditions are studied.The simulation results show that,in the noon midnight meridian,plane magnetopause shape has a concave structure.And at certain Dp,when southern IMF Bz(Bz<0) increases,the subsolar position(r0) of the magnetopause decreases and when northward(Bz>0) increases,the subsolar position r0 keeps gradually increasing.Significant decreasing of r0 appears with the increase of Dp.For all cases studied,the flare angle(z0/x0) of the magnetopause increases when(Bz<0) increases.These simulation results are consistent with the empirical results based on satellite data in high-latitude empirical model(B00) and(Schield) model.That is to say,MHD simulation is an effective tool to study the magnetopause shape.It is an effective way,based on the configuration of physical theory on magnetopause numerical simulation data,to solve the problem that relates to the obtaining of transversing data in high latitudes being limited.