二维电离层发电机理论模式及其初步应用

Two-dimension theoretical modeling of ionospheric dynamo and its preliminary application

在地理坐标系下推导出二维电离层发电机理论方程，采用逐线迭代法求解得到全球二维电离层发电机电流函数，进而得到电离层发电机电流和电场．模式中使用的电导率是根据外部经验模式给出的背景大气和电离层参数，采用理论公式计算得出；输入的中性风场和磁场分别由HWM93和IGRF2000模型给出，该电离层发电机理论模式很好地给出了全球Sq电流形态及电离层E层发电机电场的基本特征．利用该模式研究了外部模式风场以及地磁场随高度的变化对模拟结果的影响，发现在90～180km高度上，风场随高度变化对电流影响较大，而地磁场影响较小；重点模拟研究了地磁平静时期，Sq电流涡旋中心位置和总电流强度的变化规律，初步研究发现，电流中心位置在地理纬度±30°附近，不同的地方时电流随地磁纬度线平行移动，且南北半球两个电流涡中心电流强度之和变化不大．分析发现这种规律与发电机高度上的磁场总强度及地磁倾角的全球分布有很好的相关性．

In the geographic coordinate system, two-dimension theoretical ionospheric dynamo equation has been deduced. After solving this equation with the iteration method, we get the two- dimension current functions. Thereafter the ionospheric current and electric field are derived. Conductivities used in this model are calculated by the theoretical formulas. The parameters of background atmosphere and ionosphere in the formulas are given by external empirical models. Neutral winds and magnetic field are obtained from the HWM93 and IGRF2000 models respectively. This ionospheric theoretical dynamo model satisfactorily gives the shape of global Sq current and the characteristic of ionospheric dynamo electric field. In addition, the effects of altitude variation of winds and geomagnetic field on the simulation results have been investigated. It shows that in the heights from 90 km to 180 kin, the result changes little with the altitude variation of magnetic field, but there is a distinct change with the height variation of winds.During the geomagnetic quiet period, we research the patterns of the Sq current loci and the total current intensity. Initial analysis shows that these patterns have a good correlation with the global distribution of geomagnetic field intensity.