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Westward drift in secular variation of the main geomagnetic field inferred from IGRF
Earth, Planets and Space volume 55, pages131–137(2003)
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.
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Wei, Z., Xu, W. 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
- Drift Rate
- Secular Variation
- Magnetic Component
- Earth Planet Space
- Magnetic Potential