极端太阳风条件下的磁层顶位形

摘要

基于极端太阳风条件下的三维MHD数值模拟数据,构建了一种极端太阳风条件下的三维非对称磁层顶位形模型.所提出的模型考虑了行星际南向磁场（IMF）B_z日下点距离侵蚀的饱和效应,太阳风动压Pd对磁层顶张角影响的饱和效应,赤道面、昼夜子午面磁层顶的不对称性以及极尖区的内凹结构和内凹中心的移动,并利用Levenberg-Marquart多参量非线性拟合方法拟合了模型参数.数值模拟研究表明,在极端太阳风条件下,随Pd增大,磁层顶日下点距离减小,磁层顶磁尾张角几乎不变;随南向（IMF）B_z增大,磁层顶日下点距离略有减小,磁层顶磁尾张角减小,极尖区内凹中心向低纬移动.通过对2010年8月1日太阳风暴事件验证发现,本文所建立的模型能够描述极端太阳风条件下的三维磁层顶位形.%Based on the 3D global MHD numerical simulation data under extreme solar wind conditions, a dynamic 3D asymmetric magnetopause model under extreme solar wind conditions is developed. This magnetopause model parameters are fitted by the Levenberg-Marquart method and this magnetopause model has the ability to describe the saturation effects of the solar wind dynamic pressure Pa on the flaring of the magnetopause, the saturation effects of the interplanetary magnetic field （IMF） B~ on the subsolar standoff distance, the magnetopause indentation in the cusp region, the magnetopause asymmetry and the movement of magnetopause indentation center. On the basis of this model under extreme solar wind conditions, the subsolar point decreases with increasing Pd and increasing Pd causes the decrease of the magnetopause size but almost keeps the magnetopause shapes self-similar; with iacreasing southward （IMF） Bz, the subsolar point decreases slightly, the flaring of the magnetopause decreases and magnetopause indentation center moves towards low- latitude. Through analysis of the solar storm on August 1, 2010, it is found that this magnetopause model can describe the global magnetopause location and shape under extreme solar wind conditions.