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Celestial Mechanics and Dynamical Astronomy

, Volume 116, Issue 2, pp 195–212 | Cite as

Asymmetric effects on Earth’s polar motion

  • Christian BizouardEmail author
  • Leonid Zotov
Original Article

Abstract

Differential equations ruling the Earth’s polar motion are slightly asymmetric with respect to the pole coordinates. This is not only associated with the lack of axial symmetry around the Earth figure axis (triaxiality) but also with the longitude dependency of the pole tide (the main contribution). We propose a consistent handling of both asymmetric contributions, formulating a unique equation in the complex equatorial plane, of which we derive a general solution. Difference with respect to the usual symmetric solution is discussed and found significant in light of the present accuracy of the observed pole coordinates. For the same geophysical excitation, the prograde Chandler wobble is accompanied by a retrograde component up to 2 milliarcseconds (mas), transforming it in a slight elliptic motion. The asymmetric contribution is relatively larger in the geodetic excitation function, for Chandler wobble excitation mixes prograde and retrograde components of comparable level (1 mas).

Keywords

Liouville equation Earth rotation Polar motion  Triaxiality Ocean  Pole tide Asymmetry Chandler wobble 

Notes

Acknowledgments

The second author is supported by Chinese Academy of Sciences Fellowship for Young International Scientists and RFBR Grant 12-02-31184. We greatly thank the reviewers for their remarks and corrections. One of them, by doing a very careful review, and making us aware of the work of Okamoto and Sasao (1977), permitted us to refine this study.

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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  1. 1.Observatoire de Paris—SYRTE UMR 8630ParisFrance
  2. 2.Sternberg Astronomical Institute of Moscow State UniversityMoscowRussia

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