Non linear Prediction of Earth Orientation Parameters
N. Rouveyrollis, D. Gambis
IERS Orientation Center - Paris Observatory UMR 8630 (France)
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Different approaches are used for prediction of the Earth rotation parameters. The IERS
product center uses the following techniques :
N Polar Motion: The formalism uses at first a floating period fit (Bevington, 1969 [2]) for
both the Chandler and annual components estimation over a past time interval of several
0
years. An autoregressive filter is then applied on the short-term residuals series and used
for the prediction. The predictions of the nutation offsets d and dH are based on an
empirical model (Conventions 1996).
N Universal Time: The present formalism used is based on the assumption that the long-
term fluctuations (annual and semi-annual) of the preceding year are valid over the next
few months. For short-term variations prediction, an autoregressive process is used.

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Another approach to predict EOP series, is using SSA method (R. Vautard et al [1]) to
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extract significant components instead of adjusting the data to an a-priori model. A
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Performing a SSA decomposition we obtain the following decomposition for the x-
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