全球电离层发电机方程的一种数值解法

为了将建立在赤道为对称面假设基础上的二维半球域对称）电离层发电机理论扩展到全球,本文在解发电机方程时,去掉赤道对称面这一假设条件和两极附加的边界条件,使通常的边值问题变成一种“无边界’问题．它更合理地描述了电离层发电机过程,而且可以给出半球发电机理论所不能给出的特征,例如,可以对Ｓｑ电流体系的ＵＴ变化、季节变化、非偶极子地磁场部分的发电机效应等南北半球不对称的情况进行数值计算．计算实例表示,在简单的赤道对称情况下,它可以复现二维半球（对称）发电机模型的结果．在不对称情况下,电流体系的强度、焦点位置、电流方向等显示出较为复杂的变化,而半球发电机理论则无法解释这些特征．

A NUMERICAL SOLUTION OF THE DYNAMO EQUATION FOR THE GLOBAL IONOSPHERE

The two-dimensional hemispherical dynamo theory is based on the symmetry aboutthe equator, and has certain inherent theoretical shortcomings and limitations in application. In order to extend the dynamo theory to the globe, the assumption of thesymmetry about the equator is removed in present study, the boundary condition atthe north (or south) pole is also removed. In this way the conventional boundaryproblem becomes "boundary--free" one, which describes more reasonably the physicsof the dynamo process and would show some essential characteristics. For instance,this method can be used to study seasonal and UT variations of the Sq currentsystem, as well as dynamo effects of the non-dipole magnetic field, all of which areasymmetric about the equator. The global current system obtained by using presentmethod for simple symmetric condition is same as that by using hemispheric symmetric dynamo theory. As for asymmetric condition, the current intensity, focus location, current direction and other characteristics show more complicated features, whichcan not be explained by hemispheric dynamo theory.