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Geomagnetic westward drift using the correlation coefficient

Naturevolume 301pages136137 (1983) | Download Citation



The westward movement in time of features of the pattern of the geomagnetic field on the surface of the Earth1 is termed the ‘westward drift’ and is supposed to occur because the Earth's outer, liquid core, where the main geomagnetic field originates, rotates more slowly than the mantle. The drift rate is not constant and it has been suggested2 that changes in the rotation rate of the core, as seen in the variation of westward drift, will be associated with changes in the rotation rate of the mantle, that is, in the observed length of day. Le Mouel et al.3 have recently presented evidence in support of this theory. Here I attempt to derive an estimate of westward drift from global models of the magnetic field, to determine whether a correlation can be found from the data. The conclusion reached is much less optimistic than that of Le Mouel et al.3 as the changes in length of day do not appear to follow closely the values of westward drift obtained.

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  1. Institute of Geological Sciences, West Mains Road, Edinburgh, EH9 3KA, UK

    • Barbara M. Hodder


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