Effects of the interplanetary magnetic field clock angle on the shape of bow shock  

作　　者：WANG JiangYan HUANG ZhaoHui WANG Chi LIU ZiQian 

机构地区：[1]State Key Laboratory of Space Weather, Center for Space Science and Applied Research,Chinese Academy of Sciences [2]College of Earth Science, University of Chinese Academy of Sciences

出　　处：《Science China Earth Sciences》2015年第7期1228-1234,共7页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41231067,41374172);the National Basic Research Program of China(Grant No.2012CB825602);the Specialized Research Fund for State Key Laboratories of China

摘　　要：Using the global magnetohydrodynamics(MHD) simulation model, we investigated the effects of the interplanetary magnetic field(IMF) clock angle on the shape of bow shock, including its rotational asymmetry and subsolar point. For general northward IMF( z component Bz > 0), the rotational symmetry of the bow shock is broken by the effects of fast magnetosonic Mach number(Mms), and the cross-sectional line of the bow shock is an ellipse with the semi-major axis along the direction perpendicular to the IMF. The ratio or D-value between semi-major and semi-minor axis can be used to illustrate the extent of asymmetry of the bow shock. On the basis of the multiple parameters fitting, we obtain the changing relationship of both semi-axes with the clock angle and the distance away from the Earth. For general southward IMF(Bz < 0), the cross sectional line of the bow shock is highly asymmetrical under the multiple effects of magnetopause and Mms. The effects of IMF clock angle on subsolar point depend mainly on the changing subsolar point of magnetopause as an obstacle. The distance of subsolar point of bow shock from the Earth increases with the increasing IMF clock angle for Bz > 0, and decreases with the increasing IMF clock angle for Bz < 0.Using the global magnetohydrodynamics（MHD） simulation model, we investigated the effects of the interplanetary magnetic field（IMF） clock angle on the shape of bow shock, including its rotational asymmetry and subsolar point. For general northward IMF（ z component Bz 〉 0）, the rotational symmetry of the bow shock is broken by the effects of fast magnetosonic Mach number（Mms）, and the cross-sectional line of the bow shock is an ellipse with the semi-major axis along the direction perpendicular to the IMF. The ratio or D-value between semi-major and semi-minor axis can be used to illustrate the extent of asymmetry of the bow shock. On the basis of the multiple parameters fitting, we obtain the changing relationship of both semi-axes with the clock angle and the distance away from the Earth. For general southward IMF（Bz 〈 0）, the cross sectional line of the bow shock is highly asymmetrical under the multiple effects of magnetopause and Mms. The effects of IMF clock angle on subsolar point depend mainly on the changing subsolar point of magnetopause as an obstacle. The distance of subsolar point of bow shock from the Earth increases with the increasing IMF clock angle for Bz 〉 0, and decreases with the increasing IMF clock angle for Bz 〈 0.

关 键 词：IMF clock angle bow shock MHD simulations 

分 类 号：P353[天文地球—空间物理学] TH714.51[天文地球—地球物理学]