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Dissipation and Ellipticity of the Chandler Wobble

Published online by Cambridge University Press:  12 April 2016

Yaozhong Zhu  and
Buxi Gao
Yaozhong Zhu
Affiliation:
Institute of Geodesy and Geophysics, Chinese Academy of Sciences, 54 Xudong Road, Wuhan, Hubei, 430077, China
Buxi Gao
Affiliation:
Institute of Geodesy and Geophysics, Chinese Academy of Sciences, 54 Xudong Road, Wuhan, Hubei, 430077, China

Abstract

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The Chandler wobble, one of the main feature of the Earth’s polar motion, is related to the properties of the mantle and liquid core as well as the mobility of the oceans. The equilibrium pole tide and mantle anelasticity both lengthen the Chandler period, moreover, the former imposes a slight ellipticity on the pole path, and the latter is responsible for the wobble energy dissipation. On the basis of the perturbation principles, we derive the theoretical Qω of the Chandler wobble, assuming that the wobble energy is totally dissipated within the mantle. The theoretical ellipticity and orientation of the semimajor axis of the Chandler wobble path for an anelastic Earth are given. Compared with the results for the elastic Earth, the effect of mantle anelasticity does not change the wobble ellipticity significantly, but slightly changes the orientation of the semimajor axis in the opposite direction. This paper has also proved that the effect of the Earth’s 3-axis feature on the wobble ellipticity is only about 19% of that of the equilibrium pole tide. Analysis of the polar motion data obtained by using modern geodetic techniques shows that the observed ellipticity and orientation of the semimajor axis agree with the theoretical results. We can deduce that the pole tide in the globe should be close to equilibrium.

Type
Part 5. Chandler and Annual Polar Motion: Observations and Excitation
Information
International Astronomical Union Colloquium , Volume 178: Polar Motion: Historical and Scientific Problems , 2000 , pp. 473 - 480
Copyright
Copyright © Astronomical Society of the Pacific 2000

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