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Westward drift in secular variation of the main geomagnetic field inferred from IGRF
Earth, Planets and Space volume 55, pages 131–137 (2003)
Abstract
Westward drift is apparent not only in the Main Geomagnetic field (MG-field) but also in its Secular Variation (SV-field). The eighth generation of International Geomagnetic Reference Field (IGRF) is used in this paper to study westward drift in the SV-field. The magnetic potential of the SV-field shows a simple spatial distribution and steady variation tendency. An average westward drift rate (0.43 degree/year) is obtained from the SV potential for 1900–2005, which is much greater than the slow westward drift of the MG-field itself (about 0.15 degree/year) for the same period. Magnetic components Y and Z of the SV-field show complicated patterns, from which the average rates of westward drift are roughly estimated as 0.39 degree/year and 0.43 degree/year, respectively. The spatial distribution of component X shows much more complicated pattern with many small-scale vertices, especially for the period 1940–1960, giving a larger drift rate (0.51 degree/year). The unusual behaviors of the high-degree Gauss coefficients in IGRF 1945, 1950 and 1955 slightly affect the spatial pattern of the potential, although they greatly distort the distribution of components X, Y and Z.
References
Barton, C. E., International Geomagnetic Reference Field: The Seventh Generation, J. Geomag. Geoelectr., 49, 123–148, 1997.
Briggs, B. H., On the analysis of moving pattern in geophysics—I. Correlation analysis, J. Atmos. Terr. Phys., 30, 1777–1788, 1968a.
Briggs, B. H., On the analysis of moving pattern in geophysics—II. Dispersion analysis, J. Atmos. Terr. Phys., 30, 1789–1794, 1968b.
Bullard, E. C., C. Freedman, H. Gellman, and J. Nixon, The westward drift of the Earth’s magnetic field, Thil. Trans. Roy. Soc, A243, 67–92, 1950.
Halley, E., An account of the cause of the change of the variation of the magnetical needle; with an hypothesis of the structure of the internal parts of the Earth, Thil. Trans. Roy. Soc. Lond, 17, 563–578, 1692.
IAGA Division 5, Working Group 8, International Geomagnetic Reference Field 2000, Geophys. J. Int., 141, 259, 2000.
Jault, D., C. Gire, and J. L. Le Mouel, Westward drift, core motions and exchanges of angular momentum between core and mantle, Nature, 333, 353–356, 1988.
Langel, R. A., The Main Field, in Geomagnetism, Vol. 1, edited by J. A. Jacobs, pp. 249–512, Academic Press, London, 1987.
Malin, S. R. C., Geomagnetic secular variation and its changes, 1942.5 to 1962.5, Geophys. J. R. astr. Soc., 17, 415–441, 1969.
Malin, S. R. C. and I. Saunder, Rotation of the Earth’s magnetic field, Nature, 248, 403–405, 1973.
Mandea, M. and S. Macmillan, International Geomagnetic Reference Field—the eighth generation, Earth Planets Space, 52, 1119–1124, 2000.
Matsushima, M. and Y. Honkura, Fluctuation of the standing and drifting parts of the Earth’s magnetic field, Geophys. J., 94, 35–50, 1988.
Tank, S. B., Rotation of the geomagnetic field about an optimum pole, Geophys. J. Int., 140, 461–464, 2000.
Wei, Z.-G. and W.-Y. Xu, Westward drift of the geomagnetic anomaly in east Asia, Chinese J. Geophys., 43(1), 49–56, 2000.
Wei, Z.-G. and W.-Y. Xu, Drift and intensity variations of the geomagnetic field, Chinese J. Geophys., 44(4), 496–505, 2001.
Wei, Z.-G. and W.-Y. Xu, Latitude-dependence and dispersion of the westward drift in the geomagnetic field, Chinese Sci. Bull., 47(4), 330–333, 2002.
Xu, W.-Y., Unusual behaviour of The IGRF during the 1945–1955 period, Earth Planets Space, 52, 1227–1233, 2000.
Xu, W.-Y., Revision of the high-degree Gauss coefficients in the IGRF 1945–1955 models by using natural orthogonal component analysis, Earth Planets Space, 54, 753–761, 2002.
Yukutake, T., The westward drift of the magnetic field of the earth, Bull. Earthquake Res. Inst., 40, 1–65, 1962. Yukutake, T., The drift velocity of the geomagnetic secular variation, J. Geomag. Geoelectr., 20, 403–414, 1968.
Yukutake, T., A stratified core motion inferred from geomagnetic secular variations, Phys. Earth Plan. Int., 24, 253–258, 1981.
Yukutake, T. and H. Tachinaka, The westward drift of the geomagnetic secular variation, Bull. Earthquake Res. Inst., 46, 1075–1102, 1968.
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Wei, ZG., Xu, WY. Westward drift in secular variation of the main geomagnetic field inferred from IGRF. Earth Planet Sp 55, 131–137 (2003). https://doi.org/10.1186/BF03351740
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DOI: https://doi.org/10.1186/BF03351740