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.

• 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。