1600-2000年地球主磁场的全球变化

根据汤普森（Thompson）地磁场模型和第 8代IGRF模型，计算了1600-2000年期间的偶极子磁场、非偶极子磁场、西向漂移和地磁功率谱等反映主磁场变化的主要参数，分析了各个参数的长期变化特征。主要结果是：400年来地磁场的偶极子磁矩持续减小，1800年以来磁心的位置快速离开地心向太平洋方向移动了291km；西向漂移有大约30年左右的周期；非偶极子磁场异常中，南大西洋正磁异常、非洲负磁异常和大洋洲负磁异常是1600年以来一直存在的 3个大型磁异常，东亚正磁异常和北美正磁异常是1700年后逐渐形成的，17世纪北太平洋地区存在强的正磁异常。

GLOBAL CHANGES OF THE GEOMAGNETIC FIELD DURING 1600-2000AD

Based on Thompson and Barraclough magnetic field models and the eighth generation of International Reference Field (IGRF), the main parameters of main magnetic field for the dipole magnetic field, the non dipole magnetic field, westward drift and geomagnetic spatial power spectrum were calculated and analyzed. The secular variations of each parameter were analyzed. The magnetic moment of magnetic dipole has been connectively decreasing since 1600. Magnetic center has departed the Earth's center quickly and moved 291km toward northern Pacific since 1800. There is an approximate 30 years periodicity for westward drift. The distribution range is very large, and the intensities are very strong, and the changes are connective for the following 3 non dipole magnetic anomaly since 1600: Southern Atlantic positive anomaly, African negative anomaly and oceania negative anomaly. Eastern Asian positive anomaly and Northern American positive anomaly are non dipole magnetic anomaly formed gradually after 1700. There is a very strong positive anomaly in the Northern Pacific during the 17th century.