Time-Delay Study of Earth Orientation Parameters at Inter-Annual Time Scales

International audienceWe proceed to a reanalysis of time series of the Earth Orientation Parameters available from IERS [4] using Takens time-delay embedding technique [5]. Focusing on intermediate time scales rather than short ones as done in [3], we extract oscillations corresponding to Chandler wobble by singular-value decomposition [7] of the time-series of the Celestial Ephemeris Pole position (PMX,PMY) on the period 1890-2000. A Pi phase-shift of the oscillation around 1930 is pointed out explicitly. A similar study of the length-of-day time series shows strong correlation with indices measuring the strength of the ENSO phenomenon on the period 1962-1999 [23]. Differences between the dynamical systems approach and conventional signal analyses are emphasized