A comparison of low-frequency variations in two data series on the coordinates of the earth's pole

A comparison of two data series on the Earth's polar oscillations at low frequencies (lower than the Chandler oscillation frequency) are discussed. One of these data series was processed in the CIO frame, and the other was processed using a new global determination of the Earth orientation parameters, Linear trends were first extracted and compared. The constant relative shift between the series is 0 ''.02 and the shift of their slopes does not exceed 0 ''.012 per century. An earlier comparison of the main periodic components (Chandler wobble and the annual component) using the same data series did not reveal any substantial discrepancies in the structure of the oscillations. The most prominent oscillations at low frequencies, with periods 42.67 and 6.40 yr, were chosen for the comparison. A two-channel autoregression analysis indicates a phase shift: the oscillations of the coordinates of the Earth's pole with period 42.67 yr in the two data series are shifted relative 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: the displacement curve for the equilibrium centers for six-year Poincare mapping sections has a period of 42.7 year.