东亚地磁场模型的计算与分析

根据中国、前苏联和蒙古等地区的地磁复测点和地磁台站资料,使用泰勒多项式方法和冠谐分析方法,计算东亚地磁场(X,Y,Z)的泰勒多项式模型和冠谐模型,以及东亚剩余磁场(ΔX,ΔY,ΔZ)的冠谐模型和泰勒多项式模型,并绘制了相应的理论地磁图. 泰勒多项式模型的展开原点位于45°N和100°E,截断阶数为7.地磁场泰勒多项式模型的均方偏差为:X分量是133.0nT,Y分量是107.4nT,Z分量是14.0nT. 球冠极点位于45°N和100°E,球冠半角为42°,冠谐模型的截断阶数为10. 剩余磁场冠谐模型的均方偏差分别为131.2nT(ΔX),112.6nT(ΔY)和13.7nT(ΔZ). 对比分析了上述两种模型. 提出了确定区域模型截断阶数的判据.

CALCULATIONS AND ANALYSES OF THE GEOMAGNETIC FIELD MODELS FOR EAST ASIA

Using the geomagnetic data from repeat stations and observatories of China, former Soviet Union and Mongolia, the Taylor polynomial models and spherical cap harmonic models are calculated for both the geomagnetic field (X, Y, Z) and the residual geomagnetic field (ΔX, ΔY, ΔZ) over Ease Asia. The geomagnetic charts and residual charts are drawn. The origin point of Taylor polynomial expansion is at 45°N and 100°E, the turncation level of Taylor polynomial models is 7. The root mean square (RMS) deviations of Taylor polynomial models of the geomagnetic field are respectively 133.0nT, 107.4nT and 148.0nT for X, Y and Z. The RMS deviations of the residual field are respectively 133.8nT, 108.3nT and 144.9nT for ΔX, ΔY and ΔZ. In the spherical cap harmonic model the pole is at 45°N and 100°E, and the half-angle is 42°, the truncation index is 10. The RMS deviations of the residual geomagnetic field for the spherical cap harmonic model are respectively 131.2nT, 112.6nT and 138.7nT for ΔX, ΔY and ΔZ, while those of the geomagnetic field are respectively 134.6nT, 112.7nT and 141.1nT for X, Y and Z. The comparisons between Taylor polynomial models and spherical cap harmonic models are made. The criteria to decide the truncation order of the regional models are discussed.