1900-2000年非偶极子磁场的全球变化

根据第７代ＩＧＲＦ模型，计算并绘制了１９００-２０００年（时间间隔为５ａ）非偶极子磁场的全球分布，计算和分析了各个磁异常中心位置和强度的变化，东亚正磁异常、大洋洲负磁异常、南大西洋正磁异常、非洲负磁异常和北美洲正磁异常是分布范围广、异常强度大的５个磁异常。南大西洋正磁异常是强度最大的磁异常。在２０世纪９０年代以前，东亚正磁异常的强度位居第２位，９０年代以后，非洲负磁异常的强度（绝对值）超过东亚正磁异常，成为第２大磁异常。磁异常强度增长最快的是非洲负磁异常、南大西洋正磁异常和大洋洲负磁异常。南大西洋正磁异常和非洲负磁异常是磁异常中心位置变化最快的两个磁异常。

GLOBAL CHANGES OF THE NON-DIPOLE MAGNETIC FIELDS FOR 1900-2000

Based on the seventh generation of International Geomagnetic Referance Field, thenondipole magnetic fields for 1900-2000 (interval is 5 years.) were calculated anddrawn, the locations and intensities of each magnetic anomaly centre at different epochwere computod and analysed, too. The distribution rangs are very large, and theintensities are very strong for the following five magnetic anomalies: Eastern Asianpositive anomaly, Oceanian negative anomaly, Southern Atlantic positive anomaly,African negative anomaly and Northern American positive anomaly. The intensity ofSouthern Atlantic positive anomaly is the biggest. The intensity of Eastern Asianpositive anomaly is the second before 1990. The intensity of African negative anomalyexceeds the Eastern Asian anomaly and becomes the second since 1990. Theincreasing rate of magnetic anomaly intensity (absolute value) of African negativeanomaly is the largest (average annual variation rate is 67.1 NT/a), that of SouthernAtlantic positive anomaly is the second (that is 64.8 NT/a), that of Oceanian negativeanomaly is the third (that is 49.6 nT / a). The location changes of magnetic anomalycentre of African and Southern Atlantic anomaly are the fastest in the all of themagnetic anomalies.