1980-2010地磁场的变化

Global changes of the geomagnetic field during 1980-2010

利用第11代IGRF模型,研究了1980-2010年期间的地球主磁场的变化特性,其中包括偶极子磁场、非偶极子磁场、西向漂移和非偶极磁场强度.结果显示1980-2010年30年期间,非偶极子磁场异常中,南大西洋正磁异常、非洲负磁异常、大洋洲负磁异常、北美正磁异常区域西漂现象任然存在,而东亚正磁异常区域具有一定的东向漂移趋势.异常区除了存在西漂之外,其强度也在不断变化的,2010年南大西洋正磁异常Z分量大小相比1900年增加了41.2%,1980年以来以73.8 nT/yr的速度增长,相比上个世纪速度在增加.非洲负磁异常增加了59.4%,1980年以来以48.0 nT/yr的速度增长.这个增长速度低于上个世纪平均增长速度(64.9 nT/yr).东亚正磁异常增加了21.6%,近三十年以11.67 nT/yr的速度增加.大洋洲负磁异常110年增加了58%,并且现在还以41.3 nT/yr的速度增长.而北美正磁异常减少了40.7%,并且有减弱的越来越快的趋势,110年来平均减小的速度为30.2 nT/yr,而近三十年以49.46 nT/yr的速度减弱.

Based on the eleventh generation of International Geomagnetic Reference Field （IGRF） models, the parameters of main magnetic field were calculated, the parameters includes the dipole magnetic field, the non-dipole magnetic field, westward drift and the non-dipole magnetic field intensity, the secular variations feature of each parameter were analyzed. The magnetic moment of magnetic dipole has been decreasing since 1980, and the magnetic moment of magnetic non-dipole has been increasing during the same period. Five magnetic anomaly area were analyzed, the geomagnetic vertical component of the South Atlantic magnetic anomaly, the African anomaly, the Australia anomaly and the Eastern Asian anomaly growth of 73. 8 nT/yr,48. 0 nT/yr,41. 3 nT/yr, ll. 67 nT/yr, and the geomagnetic vertical component of the North America magnetic anomaly at decreases Speed of 49. 46 nT/yr. During 1980- 2010, the South Atlantic magnetic anomaly, the African anomaly, the Australia anomaly and the North America magnetic anomaly are moving westward, hut the Eastern Asian anomalv are moving eastward.