Based on the feature of the variations of the 11-year-period for the three components X,Y and Z of APIA,HONOLULU and PAMATAI observatories,we can conclude that the 11-year-variation in this region is of internal.

• 综合APIA、HONOLULU、PAMATAI3个地磁台三分量的11年周期变化的形态后,可定性地提出该变化源于内场。