Displacement of conjugate point during a substorm in a global MHD simulation
Displacement of conjugate point during a substorm in a global MHD simulation
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全球 MHD 模拟中亚暴期间共轭点的位移
DOI：
10.1029/2010ja016155
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
N. Sato 他9名
中科院分区：
文献类型：
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作者：
Saita;S.;A. Kadokura;N. Sato 他9名
利用数值磁流体动力学模拟再现了行星际磁场（IMF）条件下的磁层重构。为了研究地磁共枕点的相对位移，我们追踪了正IMFBy和负IMFBy条件下磁层重构过程中地磁场线的足迹。几个类似亚暴的特征，即近地中性线的形成，快速向地球的流动和等离子体团的尾部释放，发生在IMF向南转向后约1小时。从近地磁尾追踪到的测得磁力线在亚暴爆发后分别在北部和南部强烈地向黄昏方向扭曲，分别为正和负的IMFBy。最大的相对纵向位移的足迹是4.5和5.5小时的磁当地时间为正和负IMFBy，分别。虽然观测研究已经表明IMF方向是控制共扼点相对位移的主要因素，但目前基于恒定IMF方向的模拟研究首次表明，等离子体压力，磁场强度，以及沿场线沿着的场向电流密度分布可能是控制共轭体相对位移的主要因素点
We reproduce a magnetospheric reconfiguration under southward interplanetary magnetic field (IMF) conditions using numerical magnetohydrodynamic simulations. To investigate the relative displacements of the geomagnetic conjugate points, we trace both footprints of the geomagnetic field lines during the magnetospheric reconfiguration under positive and negative IMFByconditions. Several substormlike features, namely, the formation of a near‐Earth neutral line, a fast earthward flow, and tailward releases of the plasmoid, occur about 1 h after a southward turning of the IMF. The surveyed field line traced from the near‐Earth magnetotail was strongly distorted duskward in the north and south after the substorm onset for positive and negative IMFBy, respectively. The maximum of the relative longitudinal displacement of both footprints is 4.5 and 5.5 h in magnetic local time for positive and negative IMFBy, respectively. While observational studies have indicated that the IMF orientation is the main factor controlling the relative displacement of the conjugate points, the present simulation‐based study with a constant IMF orientation shows for the first time that the combined effects of plasma pressure, magnetic field intensity, and the field‐aligned current density distribution along the field line are likely to be major factors controlling the relative displacement of conjugate points.