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Detection of phase disturbances of free core nutation of the Earth and their concurrence with geomagnetic jerks


We detected phase disturbances of the Free Core Nutation (FCN) of the Earth directly from the analysis of the Very Long Baseline Interferometer (VLBI) observation of the Earth rotation for the period 1984–2003 by applying the Weighted Wavelet Z-Transform (WWZ) method and the Short-time Periodogram with the Gabor function (SPG) method. During the period, the FCN had two significant phase disturbances in 1992 and 1998. These epochs coincide with the reported occurrence of geomagnetic jerks.


  • Bellanger, E., J.-L. Le Mouel, M. Mandea, and S. Labrosse, Chandler wobble and geomagnetic jerks, Physics of the Earth and Planetary Interiors, 124, 95–103, 2001.

    Article  Google Scholar 

  • Bellanger, E., D. Gibert, and J.-L. Le Mouel, A geomagnetic triggering of Chandler wobble phase jumps?, Geophys. Res. Lett., 29, 28–1, 2002.

    Article  Google Scholar 

  • Cox, C. M. and B. F. Chao, Detection of a large-scale mass redistribution in the terrestrial system since 1998, Science, 297, 831–833, 2002.

    Article  Google Scholar 

  • Dehant, V., M. Feissel-Vernier, O. de Viron, C. Ma, M. Yseboodt, and C. Bizouard, Remaining error sources in the nutation at the submilliarc second level, J. Geophys. Res., 108, ETG 13–1, 2003.

    Google Scholar 

  • Foster, G., Wavelets for period analysis of unevenly sampled time series, Astron. J., 112, 1709–1729, 1996.

    Article  Google Scholar 

  • Gabor, D., Theory of communication, 93, 429–457, 1946.

    Google Scholar 

  • Getino, J. and J. M. Ferrandiz, Effects of dissipation and a liquid core on forced nutations in Hamiltonian theory, Geophys. J. I., 142, 703–715, 2000.

    Article  Google Scholar 

  • Gibert, D., M. Holschneider, and J.-L. Le Mouel, Wavelet analysis of the Chandler wobble, J. Geophys. Res., 103, 27069–27089, 1998.

    Article  Google Scholar 

  • Hinderer, J., J. P. Boy, P. Gegout, P. Defraigne, F. Roosbeek, and V. Dehant, Are the free core nutation parameters variable in time?, Earth Planet. Sci. Lett., 117, 37–49, 2000.

    Article  Google Scholar 

  • Huy, M. L., M. Alexandrescu, G. Hulot, and J.-L. Le Mouel, On the characteristics of successive geomagnetic jerks, Earth Planets Space, 50, 723–732, 1998.

    Article  Google Scholar 

  • Huy, M. L., M. Mandea, J.-L. Le Mouel, and A. Pais, Time evolution of the fluid flow at the top of the core. Geomagnetic jerks, Earth Planets Space, 52, 163–173, 2000.

    Article  Google Scholar 

  • Lambeck, K., The earth’s variable rotation: Geophysical causes and consequences, Cambridge Monographs on Mechanics and Applied Mathematics, 1980.

    Google Scholar 

  • Malkin, Z. and D. Terentev, Investigation of the Parameters of the Free Core Nutation from VLBI data, Communications of the IAA RAS, 149, 2003.

  • Mandea, M., E. Bellanger, and J.-L. Le Mouel, A geomagnetic jerk for the end of the 20th century?, Earth Planet. Sci. Lett., 183, 369–373, 2000.

    Article  Google Scholar 

  • Mathews, P. M., T. A. Herring, and B. A. Buffett, Modeling of nutation and precession: New nutation series fornonrigid Earth and insights into the Earth’s interior, J. Geophys. Res., 107, ETG 3–1, 2002.

    Google Scholar 

  • Roosbeek, F., P. Defraigne, M. Feissel, and V. Dehant, The free core nutation period stays between 431 and 434 sidereal days, Geophys. Res. Lett., 26, 131–134, 1999.

    Article  Google Scholar 

  • Sasao, T., S. Okubo, and M. Saito, A Simple Theory on Dynamical Effects of Stratified Fluid Core upon Nutational Motion of the Earth, Proceedings of IAU Symposium No. 78, 165, 1980.

    Google Scholar 

  • Sato, T., Y. Tamura, T. Higashi, S. Takemoto, I. Nakagawa, N. Morimoto, Y. Fukuda, J. Segawa, and N. Seama, Resonance parameters of the free core nutation measured from three superconducting gravimeters in Japan, J. Geomag. Geoelect., 46, 571–586, 1994.

    Article  Google Scholar 

  • Shirai, T. and T. Fukushima, Construction of a new forced nutation theory of the nonrigid Earth, Astron. J., 121, 3270–3283, 2001a.

    Article  Google Scholar 

  • Shirai, T. and T. Fukushima, Detection of excitations of free core nutation of the Earth and their concurrence with huge earthquakes, Geophys. Res. Lett., 28, 3553–3557, 2001b.

    Article  Google Scholar 

  • Toomre, A., On the ‘1nearly diurnal wobble’ of the earth, Geophys. J., 38, 335–348, 1974.

    Article  Google Scholar 

  • Wardinski, I., M. Mandea, and R. Holme, The Origin of Geomagnetic Jerks, Revisited, AGU, Fall Meeting 2002, GP31D-0769, 2003.

    Google Scholar 

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Correspondence to Toshimichi Shirai.

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Shirai, T., Fukushima, T. & Malkin, Z. Detection of phase disturbances of free core nutation of the Earth and their concurrence with geomagnetic jerks. Earth Planet Sp 57, 151–155 (2005).

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