%0 Journal Article
%T Latitude-dependence and dispersion of the westward drift in the geomagnetic field
%A Zigang Wei
%A Wenyao Xu
%J Chinese Science Bulletin
%@ 1861-9541
%D 2002
%I 
%R 10.1360/02tb9079
%X The main geomagnetic field models of IGRF1900¨C2000 are used to study the latitude-dependence of the westward drift in the main field. The results show that the latitude-dependence exists in the magnetic components with different wavelengths (m=1¨C10). The global-average westward drift rate of the component of m=1 is 0.189¡ã/a with the maximum of 0.295¡ã/a at latitudes 40¡ã¨C45¡ã. The component of m=2 has an average drift rate of 0.411¡ã/a with the maximum of 1.305¡ã/a at latitude  60¡ã. 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 note 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.
%K main geomagnetic field
%K westward drift
%K dispersion
%K hydromagnetic fluid
%U http://link.springer.com/article/10.1360/02tb9079