Differential Rotation Driven by Precession |
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Authors: | Keke Zhang Xinhao Liao Ligang Li |
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Institution: | (1) Shanghai Astronomical Observatory, Shanghai, 200030, China, e-mail;(2) School of Mathematical Sciences, University of Exeter, EX4 4QE, U.K |
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Abstract: | The tidal force in the Earth–Moon system exerted on the Earth's equatorial bulge results in the Earth's precession. It was proposed a long time ago that the strong shear flow driven by the precession of the Earth may power the Earth's dynamo in its liquid core. We present a nonlinear analytical study investigating how the Poincaré force in a rotating, precessing spherical system drives a large-amplitude differential rotation which plays a major role in the modern theory of the geodynamo. The analysis is based on a perturbation approach in terms of the small Poincaré force parameter. It is found that the amplitude of the precession-driven differential rotation is consistent with that estimated from the geomagnetic secular variation. |
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Keywords: | Earth precession Earth's differential rotation |
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