Linear drift and periodic variations observed in long time series of polarmotion

Two long time series were analysed: the C01 series of the International Ear th Rotation Service and the pole series obtained by re-analysis of the clas sical astronomical observations using the HIPPARCOS reference frame. The li near drift of the pole was determined to be 3.31 +/- 0.05 milliarcseconds/y ear towards 76.1 +/- 0.80 degrees west longitude. For the least-squares fit the a priori correlations between simultaneous pole coordinates x(p), y(p) were taken into account, and the weighting function was calculated by esti mating empirical variance components. The decadal variations of the pole pa th were investigated by Fourier and wavelet analysis. Using sliding windows , the periods and amplitudes of the Chandler wobble and annual wobble were determined. Typical periods in the variable Chandler wobble and annual wobb le parameters were obtained from wavelet analyses.