二十世纪的地球偶极子磁场

1900~2000年的IGRF(国际地磁参考场)资料使研究20世纪中地磁场的变化规律成为可能,在20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,1960年起向西和向南快速移动,偶极子轴在纬度方面变化只有1°左右,经度变化在3°左右,离磁极倒转的条件差得远.

The geomagentic dipole field in the 20th century

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 1930turned over,and it began to drift westward and southward after 1960.The direction of the axis of the dipole by about 1°in latitude and by about 3°in longitude in 20th century.That is far away from the reverse of the gomagnetic poles.