The westward drift of the lithosphere: A tidal ratchet?

Abstract. Empirical flow field data evaluation in a well studied ocean region along the U.S. West Coast revealed a surprisingly strong relationship between the surface integrals of kinetic energy and enstrophy (squared vorticity). This relationship defines a single isolated Gaussian super-vortex, whose fitted size parameter is related to the mean eddy size, and the square of the fitted height parameter is proportional to the sum of the square of all individual eddy amplitudes obtained by standard vortex census. This finding allows a very effective coarse-grained eddy statistics with minimal computational efforts. As an illustrative example, the westward drift velocity of eddies is determined from a simple cross correlation analysis of kinetic energy integrals.

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A fast-moving feature of westward drift

Annals of Geophysics ◽

10.4401/ag-3696 ◽

1999 ◽

Vol 42 (1) ◽

Author(s):

D. R. Barraclough ◽

S. R. C. Malin

Keyword(s):

Fast Moving ◽

Drift Rate ◽

Magnetic Declination ◽

Dominant Feature ◽

Westward Drift ◽

Adequate Data

he dominant feature in the magnetic declination record at all European sites for which adequate data are available is a minimum between 1750 and 1860. The time of minimum at different sites correlates well with longitude and implies a westward drift rate of 0.61 ± 0.08° yr-1. This is greatly in excess of the widely adopted value of 0.18° yr-1 for global westward drift.

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The westward drift of the Earth's magnetic field

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1950.0014 ◽

1950 ◽

Vol 243 (859) ◽

pp. 67-92 ◽

Cited By ~ 303

Keyword(s):

Magnetic Field ◽

Secular Variation ◽

Outer Part ◽

Earth’S Magnetic Field ◽

Dynamo Theory ◽

The Core ◽

The Earth ◽

Earth's Magnetic Field ◽

Harmonic Analyses ◽

Westward Drift

The westward drift of the non-dipole part of the earth’s magnetic field and of its secular variation is investigated for the period 1907-45 and the uncertainty of the results discussed. It is found that a real drift exists having an angular velocity which is independent of latitude. For the non-dipole field the rate of drift is 0.18 ± 0-015°/year, that for the secular variation is 0.32 ±0-067°/year. The results are confirmed by a study of harmonic analyses made between 1829 and 1945. The drift is explained as a consequence of the dynamo theory of the origin of the earth’s field. This theory required the outer part of the core to rotate less rapidly than the inner part. As a result of electromagnetic forces the solid mantle of the earth is coupled to the core as a whole, and the outer part of the core therefore travels westward relative to the mantle, carrying the minor features of the field with it.

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