二十世纪的地球偶极子磁场

The geomagnetic dipole field in the 20th century

190 0～ 2 0 0 0年的IGRF(国际地磁参考场 )资料使研究 2 0世纪中地磁场的变化规律成为可能 .在 2 0世纪中 ,即使从 19世纪起 ,地球偶极子磁场发生了较大的变化 ,偶极矩一直保持衰减的势头 ,地心轴的所有 3个分量都是减小的 .地磁南极的位置变化在 1930年左右发生大的转折 ,196 0年起向西和向南快速移动 .偶极子轴在纬度方面变化只在 1°左右 ,经度变化在 3°左右 ,离磁极倒转的条件还差得远 .

The study of the variations of the geomagnetic field in the 20th century becomes possible because the IGRF (International Geomagnetic Reference Field) data in 1900～2000 are available. During the 20th century, even after 19th century, the magnetic dipole moments have changed much. And the all three components of the Earth's center dipole decreased much in the last century. The variation of the positions of the geomagnetic south pole in about 1930 turned over, and it began to drift westward and southward after 1960 The direction of the axis of the dipole only changed by about 1° in latitude and by about 3° in longitude in 20 th century. That is far away from the reverse of the geomagnetic poles.