地磁场区域模型与全球模型的比较和讨论

人们常用球谐分析方法来表示地磁场的全球分布(即全球模型,Definite Geomagnetic Re-ference Field,以下简称DGRF),用多项式表示地磁场的区域分布(即区域模型).本文以1980年中国地区地磁场区域模型(Chinese Geomagnetic Reference Field,以下简称CGRF)和DGRF1980为例,计算出地磁场区域模型与全球模型的差值(Dif=CGRF1980-DGRF1980),用电子计算机绘制出差值的等值线图,并进行了讨论.从差值等值线图可以看出:对于中国大部分地区,地磁场的区域模型与全球模型之间的差值比较小,但在西北和东北边境地区,其差值明显增大.

A COMPARISON BETWEEN REGIONAL MODEL ANDGLOBAL MODEL OF THE GEOMAGNETIC FIELD

Spherical harmonic analytical method is usually used to express the globaldistribution of the geomagnetic field (global model), and polynomial method isemployed to express the regional distribution of the geomagnetic field (regionalmodel). In this paper, on the basis of the regional models of the geomagneticfield in China at epoch 1980.0 (CGRF 1980) and the global models of the geo-magnetic field at epoch 1980.0 (DGRF 1980), the differences between CGRF1980 and DGRF 1980 were calculated (diff. =CGRF 1980-DGRF 1980), andcontour maps of the differences were constructed for total intensity (F), verti-cal intehsity (Z), horizontal intensity (H), declination (D) and inclination (I),with some analyses and discussions made. These maps show that the differencesbetween CGRF 1980 and DGRF 1980 are comparatively small in most parts ofChina, but obviously grow larger in border areas of Northwest and Northeast China.