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Modelling and prediction of the FCN

Journées 2005. Syst è mes de Référence Spatio-Temporels. Modelling and prediction of the FCN. Maciej Kalarus 1 Brian Luzum 2 S é bastien Lambert 2 Wiesław Kosek 1. 1 Space Research Centre, Polish Academy of Sciences 2 United States Naval Observatory. Warsaw, 19-21 September 2005.

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Modelling and prediction of the FCN

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  1. Journées 2005 Systèmes de Référence Spatio-Temporels Modelling and predictionof the FCN Maciej Kalarus1 Brian Luzum2 Sébastien Lambert 2 Wiesław Kosek 1 1Space Research Centre, Polish Academy of Sciences 2United States Naval Observatory Warsaw, 19-21 September 2005

  2. Nutation residuals IERS C04 (1984 - August 2005) daily data IAU 2000 Atmospheric Angular Momentum NCEP/NCAR (1984 - August 2005) four-times daily data reanalyses Gravity field C20 Cox & Chao (1984 - December 2002) variable Input data Modelling and prediction of the FCN 2/9

  3. Complex Wavelet Transform Coefficients T - dilation parameter (scale) ti - translation parameter (space) Complex Morlet Wavelet fb – bandwidth parameter fc – wavelet centre frequency Wavelet analysis Modelling and prediction of the FCN 3/9

  4. Wavelet transform modulus high Period [days] amplitude low Gradient of the phase + + + 0 0 0 - - _ Wavelet analysis of the nutation residuals Period [days] Modelling and prediction of the FCN 4/9

  5. Level of the residuals FCN - model dXMHB2000 dYMHB2000 Modelling and prediction of the FCN 5/9

  6. RMS prediction error error computed in 1986 – 2004 Distribution of the prediction errors for 180 days in the future dX dY Prediction of the FCN model Modelling and prediction of the FCN 6/9

  7. El Niño event 1997/98 nino4 Gravity field C20 FCN period annual AAMp Wavelet transform modulus FCN AAM annual oscillation Possible excitation of the FCN Modelling and prediction of the FCN 7/9

  8. Conclusions Characteristic of the FCN model - variable amplitude and period (phase) - mean prediction error - 70-80as for 180 days in the future - apparent relationship to geophysical phenomena Possible excitation of the FCN - global mass redistribution - land hydrology Impulse excitation - perturbations of the annual atmospheric and oceanic circulation Other possible sources of excitation - subpolar glacial melting(J. O. Dickey, S. L. Marcus, O. de Viron, I. Fukumori) - earthquakes(T. Shirai, T. Fukushima) - anomalous fluctuations in the core(C. M. Cox, B. F. Chao) Modelling and prediction of the FCN 8/9

  9. Acknowledgements: This research has been partially supported by the Descartes-Nutation project. Thank you for your attention

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