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Encyclopedia of Solid Earth Geophysics pp 1–16Cite as

Core-Mantle Coupling

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Part of the book series: Encyclopedia of Earth Sciences Series ((EESS))

Definition, Scope, and Aims

The Earth is not a perfect timekeeper, and the spectrum of the variations in the mantle’s angular velocity \( \hat{\boldsymbol{\Omega}} \) spans a wide range of frequencies. Of particular interest here are the comparatively large amplitude decadal and semidecadal variations in which changes in length of day, P, of up to 2 ms occur. These would not be explained even if the global circulations of the atmosphere and oceans could be reversed. This is confirmed by a more detailed argument given in our recent review (Roberts and Aurnou 2012), which will be referred to here as “RA12.”

The origin of these length of day (LOD) variations must be sought in the Earth’s core, and Fig. 1 suggests that the task is not an easy one. Fig. 1b shows dP/dt, derived by differentiating smoothed LOD data from the last half century, with atmospheric, oceanic, and tidal signals removed; semi-decadal time variations are clearly seen with a period τLODof about 6 years (e.g., Abarca...

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Acknowledgments

We thank Richard Gross, Richard Holme, and Andrew Jackson for sharing their insights and their data. We are also grateful to Bruce Buffett and the referee (Mathieu Dumberry) for giving helpful advice.

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Authors and Affiliations

  1. Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA, USA

    Paul H. Roberts

  2. Department of Earth and Space Sciences, University of California, Los Angeles, CA, USA

    Jonathan M. Aurnou

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  1. Paul H. Roberts
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Correspondence to Paul H. Roberts .

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Editors and Affiliations

  1. Seismology, National Geophysical Research Insti, Hyderabad, India

    Harsh K. Gupta

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Roberts, P.H., Aurnou, J.M. (2020). Core-Mantle Coupling. In: Gupta, H. (eds) Encyclopedia of Solid Earth Geophysics. Encyclopedia of Earth Sciences Series. Springer, Cham. https://doi.org/10.1007/978-3-030-10475-7_39-1

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