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.
出处
《空间科学学报》
CAS
CSCD
北大核心
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
