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磁层顶位置和形状的动态特征描绘是地球物理和空间物理研究的难点之一. 文章基于太阳风-磁层-电离层耦合的全球磁流体力学(MHD)数值模拟, 运用电流密度极大法确定磁层顶位形, 并具体研究两种典型太阳风动压(Dp)和几种不同行星际磁场的z分量(Bz)条件下, 地球赤道面上方磁层顶动态特征. 模拟结果显示, 磁层顶日下点高度r0主要由Dp控制. 随着Dp增加, 磁层顶被压缩, r0显著减小. 相同Dp条件下, 在Bz由南向(Bz0)逐渐减小, 并转为北向(Bz0)逐渐增大的过程中, r0缓慢增大. 不同条件下, 磁层顶张角变化较小, 反映了赤道面磁层顶结构的相似性. 与Shue98低纬磁层顶经验模型比较, MHD模拟能再现磁层顶日下点位置r0对Dp的响应, 而r0随Bz变化的饱和性仅出现在低速太阳风条件下. MHD模拟和经验模型的磁层顶张角差别小于2.5, 但模拟显示随Bz的变化趋势并非简单线性关系.The determination of the varying position and shape of magnetopause is one of the important Gordian knots in geophysics and space physics. According to the solar wind-magnetosphere-ionosphere coupling global magnetohydrodynamic (MHD) simulation, and with the maximum electric current criterion, we study the position and shape of the magnetopause under several solar wind dynamic pressure (Dp) and interplanetary magnetic field conditions. The simulation results show that the subsolar position (r0) of the magnetopause is controlled mainly by Dp with the significant decrease of r0 as Dp increases. At a certain Dp, when southword Bz (Bz0) decreases to zero, then shifts to northward (Bz0) and increases, the subsolar position r0 keeps increasing. For all cases studie here, the flare angle () of the magnetopause experiences small changes. This provide an evidence for the structural self-similarity of magnetopause in equatorial plane. Compared with the empirical low-latitude magnetopause model of Shue98, MHD simulation can reproduce the dependence of the subsolar point r0 on Dp, while the saturation effect of r0 varying with Bz in empirical model is represented only with slow solar wind. As to the flare angle , although the difference between MHD simulation and empirical model is less than 2.5, the variation of with Bz in MHD simulations is nonlinear and different from the linear trend in empirical model.
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Keywords:
- equatorial magnetopause /
- location and shape /
- MHD simulation
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[2] Tu C Y 1988 Solar Terrestrial Physics (Beijing: Science Press) (in Chinese) [涂传诒 1988 日地空间物理学(下册) (北京: 科学出版社)]
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[6] Lü J Y, Yang Y F, Du D 2011 Adv. Met Sci. Tech. 1 26 (in Chinese) [吕建永, 杨亚芬, 杜丹 2011 气象科技进展 1 26]
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[21] Hu Y Q, Guo X C, Wang C 2005 Chin. Phys. Lett. 22 2273
[22] Hu Y Q, Guo X C, Wang C 2007 J. Geophys. Res. 112 7215
[23] Wang C, Li C X, Huang Z H 2006 Geophys. Res. Lett. 33 14104
[24] Wang C, Liu J B, Huang Z H, Richardson J D 2007 J. Geophys. Res. 112 A12210
[25] Huang Z H, Wang C, Hu Y Q, Guo X C 2008 Comput. Math. Appl. 55 1094
[26] Matsumoto H, Omura Y 1993 Computer Space Plasma Physics (Tokyo: Terra Scientific Publishing Company)
[27] Wang C, Li H, Guo X C, Ding K, Huang Z H 2012 Sci. China Earth Sci. 55 1037
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[1] Stern D P 1989 Rev. Geophys. 27 103
[2] Tu C Y 1988 Solar Terrestrial Physics (Beijing: Science Press) (in Chinese) [涂传诒 1988 日地空间物理学(下册) (北京: 科学出版社)]
[3] Bothmer V, Daglis I A 2007 Space Weather—Physics and Effects (Berlin: Springer-Verlag)
[4] Wang S, Wei F S 2007 Prog. Geophys. 22 1025 (in Chinese) [王水, 魏奉思 2007 地球物理学进展 22 1025]
[5] Lü J Y, Wang J S 2010 Space Weather (Beijing: Meteorology Press) (in Chinese) [吕建永, 王劲松 2010 空间天气学 (北京: 气象出版社)]
[6] Lü J Y, Yang Y F, Du D 2011 Adv. Met Sci. Tech. 1 26 (in Chinese) [吕建永, 杨亚芬, 杜丹 2011 气象科技进展 1 26]
[7] Sotirelis T, Meng C I 1999 Geophys. Res. 104 6889
[8] Fairfield D H 1971 J. Geophys. Res. 76 6700
[9] Lü J Y, Liu Z Q , Kabin K 2011 J. Geophys. Res. 116 A09237
[10] Liu H L, Huang Z H 2011 Chin. J. Space Sci. 31 15 (in Chinese) [刘惠莲, 黄朝晖 2011 空间科学学报 31 15]
[11] Roelof E C, Sibeck D G 1993 J. Geophys. Res. 98 421
[12] Kawano H, Petrinc S M, Russell C T, Higuchi T 1999 J. Geophys. Res. 104 247
[13] Petrinec S M, Russell C T 1996 J. Geophys. Res. 101 137
[14] Shue J H, Chao J, Fu H C 1997 J. Geophys. Res. 102 9497
[15] Shue J H, Song P, Russell C T 1998 J. Geophys. Res. 103 17691
[16] Boardsen S A, Eastman T E, Sotierlis T, Green J L 2000 J. Geophys. Res. 23 193
[17] Kalegaev V V, Lyutov Y G 2000 Adv. Space Res. 25 1489
[18] Lin R L, Zhang X X, Liu S Q, Wang Y L, Gong J C 2010 J. Geophys. Res. 115 A04207
[19] Wang C 2011 Chin. J. Space Sci. 31 413 (in Chinese) [王赤 2011 空间科学学报 31 413]
[20] Tóth G, Sokolv I V, Gombosi T I 20052007 J. Geophys. Res. 110 A12226
[21] Hu Y Q, Guo X C, Wang C 2005 Chin. Phys. Lett. 22 2273
[22] Hu Y Q, Guo X C, Wang C 2007 J. Geophys. Res. 112 7215
[23] Wang C, Li C X, Huang Z H 2006 Geophys. Res. Lett. 33 14104
[24] Wang C, Liu J B, Huang Z H, Richardson J D 2007 J. Geophys. Res. 112 A12210
[25] Huang Z H, Wang C, Hu Y Q, Guo X C 2008 Comput. Math. Appl. 55 1094
[26] Matsumoto H, Omura Y 1993 Computer Space Plasma Physics (Tokyo: Terra Scientific Publishing Company)
[27] Wang C, Li H, Guo X C, Ding K, Huang Z H 2012 Sci. China Earth Sci. 55 1037
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