内磁层电流体系的地磁效应

对Ⅱ区场向电流及其伴随的部分环电流和电离层电流组成的内磁层三维电流体系（PRFI电流系）的磁场效应进行了数值计算.这一三维电流体系在中低纬度地面产生的磁场呈现出特殊的纬度分布:X分量几乎不随纬度变化,Y分量随纬度增高近似呈线性变化.这些特征明显不同于对称环电流的磁场分布特征（X∝ cosφ,φ是纬度,Y=0）,也不同于DP2、S_q、L等电流体系的磁场分布特征.利用这一特征我们可以从地磁台子午链观测到的磁场扰动中分离出PRFI电流系的贡献.用1989年3月磁暴的实例检验了上述模型,观测结果与理论结果符合得很好.分析结果还表明,最大的D_st指数并不一定对应着最强的对称环电流.

GEOMAGNETIC EFFECTS OF THE INNER MAGNETOSPHERIC CURRENT SYSTEM

The geomagnetic effects of a 3-d inner-magnetospheric current system （PRFI current system） of the regionⅡ field-aligned currents and associated partial ring currents and ionospheric currents have been calculated. The magnetic field exhibits a characteristic distribution on the ground surface of mid-low latitudes: no latitudinal variations in X component, and linear variations with respect to latitude in Y component. These features are different from those of the magnetic fields caused by the symmetric ring current （X∞ cosφ, φ magnetic latitude, Y = 0）, and DP2 S,, L. These features make it possible to recognize and separate the contributions of PRFI current system from the total magnetic disturbances observed at a mid-low latitude me-xidian chain of magnetometers. This model has been examined by using the data obtained during the major storm on March 13-14, 1989. The results show that the greatest Dst index does not correspond to the strongest symmetric ring current.