Abstract
The main geomagnetic field models of IGRF1900–2000 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=1–10). The global-average westward drift rate of the component of m=1 is 0.189°/a with the maximum of 0.295°/a at latitudes 40°–45°. The component of m=2 has an average drift rate of 0.411°/a with the maximum of 1.305°/a at 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 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.
Similar content being viewed by others
References
Langel, R. A., The Main Field, in Geomagnetism (ed. Jacobs, J. A.), London: Academic Press, 1987, 249–512.
Xu Wenyao, Wei Zigang, On westward drift of the Earth’s magnetic field, Progress in Geophysics (in Chinese), 1999, 14(2): 44.
Wei Zigang, Xu Wenyao, Westward drift of the geomagnetic anomly in East Asia, Chinese Journal of Geophysics (in Chinese), 2000, 43(1): 45.
Bullard, E. C., Freedman, C., Gellman, H. et al., The westward drift of the Earth’s magnetic field, Phil. Trans. R. Soc. Lond., 1950, A243: 67.
Yukutake, T., The westward drift of the magnetic field of the Earth, Bull. Earthquake, Res. Inst. Tokyo Univ., 1962, 40: 1.
Yukutake, T., A stratified core motion inferred from geomagnetic secular variations, Phys. Earth Plan. Int., 1981, 24: 253.
Malin, S. R. C., Geomagnetic secular variation and its changes, 1942. 5 to 1962. 5, Geophys. J. R. Astr. Soc., 1969, 17: 415.
Jault, D., Gire, C., Le Mouel, J. L., Westward drift, core motions and exchanges of angular momentum between core and mantle, Nature, 1988, 333: 353.
Malin, S. R. C., Saunder, I., Rotation of the Earth’s magnetic field, Nature, 1973, 248: 403.
Tank, S. B., Rotation of the geomagnetic field about an optimum pole, Geophys. J. Int., 2000, 140: 461.
Olson, P., Aurnou, J., A polar vortex in the Earth’s core, Nature, 1999, 402: 170.
Hide, R., Free hydromagnetic oscillations of the Earth’s core and the theory of the geomagnetic secular variation, Phils. Trans. R. Soc. London, 1966, A259: 615.
Bloxham, J., Gubbins, D., The secular variation of Earth’s magnetic field, Nature, 1985, 317: 777.
IAGA Division 5, Working Group 8, International Geomagnetic Reference Field 2000, Geophys. J. Int., 2000, 141: 259.
Xu Wenyao, Secular variations of the planetary-scale geomagnetic anomalies, Chinese Journal of Geophysics (in Chinese), 2001, 44(2): 180.
Glatzmair, G. A., Roberts, P. H., A three-dimensional self-consistent computer simulation of geomagnetic field reversal, Nature, 1995, 377: 203.
Xu, W. Y., Unusual behavior of the IGRF during the 1945–1955 period, Earth, Planets and Space, 2000, 52(12): 1227.
Lowes, F. J., An estimation of the errors of the IGRF/DGRF fields 1945–2000, Earth, Planets and Space, 2000, 52(12): 1207.
Author information
Authors and Affiliations
Corresponding author
About this article
Cite this article
Wei, Z., Xu, W. Latitude-dependence and dispersion of the westward drift in the geomagnetic field. Chin.Sci.Bull. 47, 330–333 (2002). https://doi.org/10.1360/02tb9079
Received:
Issue Date:
DOI: https://doi.org/10.1360/02tb9079