用场向电流的观测结果研究高纬电离层电场

本文从Triad卫星观测到的场向电流日变化的统计结果出发, 利用场向电流日变化的付里叶级数展开和简单模式法分别求出电导率均匀时和极光带电导率增强时高纬电离层电位的分析解.结果表明, 电场集中在极光区是由2区场向电流引起的.在本文所用的场向电流分布形式下, 加上Pederson电导率的升高。极光区Hall电导率的增大反而有助于电场向中纬穿透.|AL|≥100γ时, 场向电流分布对对流圈位置西向旋转起一定作用, 但极光带Hall电导率的变化是造成大角度旋转的主要原因.Perdson电导率的增大, 对旋转角无影响.结果还表明, 在不考虑电导率日夜不均匀时, 由于场向电流复杂的日变化, 也可出现对流圈的晨昏不对称性.以上的电场分布形态, 与观测的电场形态基本相符。

The Electric Field Distribution in High-latitude Ionosphere Based on the Field-aligned Currents

This paper is based on the TRIADobserved statistical diurnal Variation of the field-aligned currents. The analytical solution of the electric potential in high-latitude both under homogeneous and inhomogeneous conductivities are deduced respectively by using the simple model method and the Fourier series expansion of the observed diurnal distribution of the fieldjaligned currents. The pattern of the electric potential based on TEIADobservations and the effects of the conductivities under such conditions are discussed through the model calculation. The results show that the'shielding'of the E-fie-Ids are caused by the region 2 field-aligned currents in our case, and under the distribution of the field-aligned currents used here the enhancement of Hall conductivities in the auroral zone may even weaken the'shielding'. During |AL|≥100r, the combined efect of the two rigions of field-aligned currents may produce a 8?rotation of the convection cells, however, the further rotation of the whole pattern is the results of the enhancement of Hall conductivities in auroral zone, and the enhancement of Pederson conductivities has no effect on this rotation. It is also .shown, even without the day-night gradient of the conductivities the two eovection cells can be unsymmetrical, this unsymmetry is caused by the complicated diurnal variation of the two regions of the field-aligned currents.The structure of the oacuilated E-field based on TEIADmeasurments is in agreement reasonably with the observed E-field pattern such as by STAREand by many other experiments. The effect of the three sheet pattern of field-aligned currents pre-midnight and of the cusp current around noon are not taken into account in this work.