地球主磁场空间功率谱的变化特征

The change characteristics of the spatial power spectrum of geomagnetic main field

根据第 8代 IGRF模型 ,计算并分析了 1 90 0～ 2 0 0 0年地球主磁场和分量 X、Y、Z的空间功率谱的变化特征。结果表明 1 90 0～ 2 0 0 0年主磁场的空间功率谱呈减小趋势 ,由功率谱随谐波阶次 n的变化关系得出的非偶极子场的等效磁源位于核幔边界附近 ,而且其位置随时间变化。用 n=1 ,2两阶谐波的谱得到的等效磁源位于地球内核边缘 ,1 90 0年以来离开地心一直向外增大。

The spatial power spectrum of the geomagnetic main field and components X?Y?Z was studied using the eighth generation of International Geomagnetic Field.The results shown that the spatial power spectrum of the main magnetic field has been decreased since 1900.The radius of apparent source shell which was calculated by the slope of regression straight line of the power spectrum changed with time.The apparent source shell of non dipoles field was near CMB.The radius of the apparent source shell which was calculated using the first two harmonics for n =1,2 near the inner core and increased from the geocenter since 1900.