地磁场长期变化球谐模型SVSHM 1960-1965

本文利用1960.0-1965.0全球157个地磁台站的X、Y、Z三分量年均值资料,进行了地磁场长期变化的球谐分析。我们采用5种加权方案（从主要考虑法矩阵条件数的方案S过渡到仅考虑资料误差的方案D）,并选择5种截断水平（球谐函数的截取级次从n=4到n=8）,共作了25次分析,从获得的法矩阵条件数和拟合残差两者的分析中发现,对这一组资料球谐级数的截取级次取为n=6,而加权方案采用S^3/4 D^1/4可能是最有效的,其结果即为地磁场长期变化球谐模型SVSHM 1960-1965。

SPHERICAL HARMONIC MODEL SVSHM 1960-1965 OF GEOMAGNETIC SECULAR VARIATIONS

We make spherical harmonig salyses of geomagnetic secular variation using the annual means of three components X, Y, and Z of 157 observatories ,all over the world during 1960.0-1965.0. Twenty five analyses have been made with five different weighting approaches (ranged from the weighting approach S in which the condition number of normal matrix Is mainly considered to the weighting approach D in which only the data errors are considered) and five truncation levels (from n=4 to n = 8, where n is the maximum degree of truncated spherical harmonic series). Both the condition numbers of normal matrices and the degree of fitting of the spherical harmonic models to data in these analyses are investigated. From this investigation we find that spherical harmonic model SVSHM 1960-1965, the model with n = 6 and the weighting approach S(3/4) D(1/4) may be the most effective one based on the data stated above.