中文摘要：

古地磁学使用的虚地磁极（VGP）是在地心偶极磁场假设下计算的，由于地球非偶极磁场的存在，VGP一般不同于真地磁极（RGP）.为了定量检验非偶极磁场对VGP的影响，本文利用国际参考地磁场模型IGRF 1900-2000，在全球5°×5°的“虚拟测点”网格上计算了VGP和RGP的位置，并求出两种磁极的经纬度偏差和二者的角距离.结果表明，南极地区VGP与RGP的角距离最大，可达26°，南大西洋和欧亚大陆北部最大达到24°和18°，其余地区一般小于15°.VGP对RGP的偏差与地磁场分布有关：在非偶极磁场较弱的地区（如太平洋半球），纬度偏差一般不大（≤10°），但是在主要地磁异常区（如南大西洋和南极地区），VGP对RGP的纬度偏差可达25°.VGP对RGP的经度偏差要比纬度偏差大得多，例如在欧亚大陆北部地区，经度偏差分布在-180°到180°的大范围内.

英文摘要：

The virtual geomagnetic pole （VGP） calculated under the assumption of a central dipole field is generally different from the real geomagnetic pole （RGP） since effect of the non-dipole field. In order to quantitatively examine effects of the non-dipole field on VGP determination, the VGP and RGP are calculated at 5°× 5° virtual sites by using the IGRF 1900 - 2000 models. The results show significant departures of VGP from RGP in some major magnetic anomaly regions. The latitude departures of VGP from the RGP are as large as 25° in these anomaly regions, although they are acceptable in most sites on the earth＇s surface （less than 10°）, mainly confined in the regions with a weak intensity of the non-dipole field, such as Pacific Ocean. The longitude departures of VGP from RGP are much more remarkable, scattering in a wide range from - 180° to 180° in Eurasian continent. The angle distance between VGP and the RGP are generally within a range of 15°, except the Antarctica, South Atlantic Ocean and Eurasia regions.