极隙区场向电流对高纬电离层电场和电流体系的影响

用Ｋａｍｉｄｅ－Ｍａｔｓｕｓｈｉｔａ方法，在行星际磁场具有较小的北向分量，且｜Ｂｙ｜＞＞｜Ｂｋ｜时，对磁语和磁扰状态以及Ｂｒ＞０和Ｂｙ＜０等不同情况，分别计算了场向电流引起的电离层电势、电场和电流体系．结果表明，极隙区场向电流的存在使高纬向日面区域的电势发生畸变，当Ｂｙ＞０时，无论是磁扰还是磁静日，极隙区电场具有显著的北向分量；等离子体对流有较大的西向分量；电离层电流为东向电流．当Ｂｙ＜０时，电场和等离子体对流的方向与Ｂｙ＞０时相反；电离层电流在磁抗日有西向分量，但在磁静日没有西向分量．电导率对电场和电流体系的影响十分明显，磁扰极光带电导率增强使电流涡从背阳面向向阳而漂移，与静日相比，磁扰时极隙区场向电流引起的电场畸变更为明显，但电场和电流强度的大小却基本保持不变．

THE EFFECTS OF THE CUSP/CLEFT FIELD-ALIGNED CURRENTS ON IONOSPHERIC ELECTRIC FIELDS AND CURRENTS AT HIGH LATITUDES

A numerical simulation of electric fields and currents in the polar ionosphere were conducted by use of Kamide-Matsushita method for different cases(IMF By > 0,IMF By<0)under weakly northward IMF and |By|>> Bz The electric Potential is distorted in the dayside while cusp/cleft FAC's exit.In the cusp/cleft region,the northward electric field is predominant; the direction of plasma flow has westward component and the ionospheric currents are essentially eastward when IMF By is Positive in the quiet and disturbed day. These situations are reversed as the IMF By is negative for the ionospheric current except In quiet day.The effects of the conductivity distribution are significant for the patterns of ionospheric convection.During disturbed day as auroral conductivity enhancement the current foci shift from nightside to dusk and dawn sectors respectively.An intersting feature is that the values of elctric field and current intensity are nearly same,although the distortion of electric potential is stronger in disturbed day than inquiet day at the cusp/cleft region.