【作者】 魏自刚； 徐文耀；

【Author】 Wei Zi-Gang and Xu Wen-Yao Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100101

【机构】 中国科学院地质与地球物理研究所；

【摘要】 本文用第八代国际参考地磁场模型和纬度剖面分析法,研究了地球主磁场不同波长成分的西漂速度随纬度的变化。结果表明,各种波长成分的西漂速度均有明显的纬度依赖性,其中,一次波全球平均西漂速度为0).189°/a,最快的西漂(0.295°/a)发生在北纬40～45°;二次波的全球平均西漂速度为0.411°/a,最快的西漂(1.305°/a)发生在南纬60°;波长更短的磁场成分西漂速度较小,而且漂移只发生在较小的纬度范围内。西漂速度的纬度依赖性不能用地核整体旋转解释。本文分析还指出,西漂速度随磁场成分的波长而变化,除了一次波外,西漂速度随波长减小而逐渐减小,即磁场西漂呈现负频散特征,这一特点与Hide的磁流体波的理论预测结果也不符合。本文指出,为了合理地解释地磁场西漂,必须全面考虑地核内部复杂的流动过程。更多还原

【Abstract】 The main geomagnetic field models of IGRF1900—2000 are used to study latitude-dependence of the westward drift in the main field.The results show that latitude-dependence exists in the magnetic components with different wavelengths(m=1—10).The global-averaged westward drift rate of the component of m=1 is 0.189°/αwith the maximum 0.295°/αatlatitudes 40～45°.The component of m=2 has an average drift rate of 0.411°/αwith the maximum 1.305°/αat latitude -60°.As for the components with further shorter wavelengths the drift is generally restricted in a limited latitude range,and has many smaller drift rates.This latitude-dependence of westward drift can not be explained by rigid rotation of the Earth’s core.The results of this paper also show that there is a negative dispersion in the westward drift,namely the components of long wavelengths drift faster than those of short wavelengths.This dispersion feature is not in agreement with Hide’s MHD model.It is likely needed to find a new mechanism for explaining the observed feature of dispersion.更多还原