A COMPARISON OF LOW-FREQUENCY VARIATIONS IN 2 DATA SERIES ON THE COORDINATES OF THE EARTHS POLE

A comparison of two data series on the Earth's polar oscillations at l ow frequencies (lower than the Chandler oscillation frequency) are dis cussed. One of these data series was processed in the CIO frame, and t he other was processed using a new global determination of the Earth o rientation parameters, Linear trends were first extracted and compared . The constant relative shift between the series is 0 ''.02 and the sh ift of their slopes does not exceed 0 ''.012 per century. An earlier c omparison of the main periodic components (Chandler wobble and the ann ual component) using the same data series did not reveal any substanti al discrepancies in the structure of the oscillations. The most promin ent oscillations at low frequencies, with periods 42.67 and 6.40 yr, w ere chosen for the comparison. A two-channel autoregression analysis i ndicates a phase shift: the oscillations of the coordinates of the Ear th's pole with period 42.67 yr in the two data series are shifted rela tive to each other by 0.53 yr, and the oscillations with period 6.4 yr are shifted by 0.33 yr. Atl interrelation in phase space was found: t he displacement curve for the equilibrium centers for six-year Poincar e mapping sections has a period of 42.7 year.