%0 Journal Article
%T Dramatic variations in the Earth¡¯s main magnetic field during the 20th century
%A Wenyao Xu
%A Zigang Wei
%A Shizhuang Ma
%J Chinese Science Bulletin
%@ 1861-9541
%D 2000
%I 
%R 10.1007/BF02909699
%X Analysis of the International Geomagnetic Reference Field (IGRF) 1900¨C2000 shows that the Earth¡¯s main magnetic field has changed dramatically during the 20th century: its dipole moment has decreased by 6.5% since 1900, the strengths of its quadrupole and octupole have increased by 95% and 74%, respectively, four major planetary-scale magnetic anomalies on the Earth¡¯s surface have enhanced by 21%¨C56%, and the magnetic center has shifted 200 km towards the Pacific Ocean. These time-variation features are similar to the behavior before a geomagnetic polarity reversal.
%K Earth¡¯s main magnetic field
%K secular variation
%K geomagnetic polarity reversal
%U http://link.springer.com/article/10.1007/BF02909699