Electrodynamic Coupling in the Solar Wind-Magnetosphere-Ionosphere System  

作　　者：Hu Youqiu Wang Chi 

机构地区：[1]Chinese Academy of Sciences Key Laboratory of Basic Plasma Physics, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China [2]State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, China

出　　处：《空间科学学报》2010年第4期321-332,共12页Chinese Journal of Space Science

基　　金：Supported by grants NNSFC (40831060,40621003);NKBRSF G2006CB806304 in China

摘　　要：This paper presents a brief summary of our recent work based on global MHD simulations of the Solar wind-Magnetosphere-Ionosphere (SMI) system with emphasis on the electrodynamic coupling in the system.The main conclusions obtained are summarized as follows.(1) As a main dynamo of the SMI system,the bow shock contributes to both region 1 Field-Aligned Current (FAC) and cross-tail current.Under strong interplanetary driving conditions and moderate Alfv'en Mach numbers,the bow shock's contribution may exceed more than fifty percent of the total of either region 1 or cross-tail currents.(2) In terms of more than 100 simulation runs with due southward Interplanetary Magnetic Field (IMF),we have found a combined parameter f=E sw P sw M A -1/2 (E sw,P sw,and M A are the solar wind electric field,ram pressure,and Alfv'en Mach number,respectively):both the ionospheric transpolar potential and the magnetopause reconnection voltage vary linearly with f for small f,but saturate for large f.(3) The reconnection voltage is approximately fitted by sin 3/2 (θ IMF /2),where θ IMF is the IMF clock angle.The ionospheric transpolar potential,the voltage along the polar cap boundary,and the electric fields along the merging line however defined they may be,respond differently to θ IMF,so it is not justified to take them as substitutes for the reconnection voltage.This paper presents a brief summary of our recent work based on global MHD simulations of the Solar wind-Magnetosphere-Ionosphere （SMI） system with emphasis on the electrodynamic coupling in the system. The main conclusions obtained are summarized as follows. （1） As a main dynamo of the SMI system, the bow shock contributes to both region 1 Field-Aligned Current （FAC） and cross-tail current. Under strong interplanetary driving conditions and moderate Affven Mach numbers, the bow shock＇s contribution may exceed more than fifty percent of the total of either region 1 or cross-tail currents. （2） In terms of more than 100 simulation runs with due southward Interplanetary Magnetic Field （IMF）, we have found a combined parameter f = EswPswMA^-1/2 （Esw, Psw, and MA are the solar wind electric field, ram pressure, and Alfven Mach number, respectively）： both the ionospheric transpolar potential and the magnetopause reconnection voltage vary linearly with f for small f, but saturate for large f. （3） The reconnection voltage is approximately fitted by sin3/2（θiMF/2）, where θ1MF is the IMF clock angle. The ionospheric transpolar potential, the voltage along the polar cap boundary, and the electric fields along the merging line however defined they may be, respond differently to θ1MF, so it is not justified to take them as substitutes for the reconneetion voltage.

关 键 词：耦合系统 电离层 太阳风 磁层顶 国际货币基金组织 电动 行星际磁场 场向电流 

分 类 号：P352[天文地球—空间物理学] TN248.1[天文地球—地球物理学]