The problem of forecasting Earth pole trajectory when changing the average parameters of its motion

The change of the Earth pole motion modes based on few-parameter two-frequency model has been investigated. It is shown that the effect of the change in the average frequency during the period of the Chandler and annual harmonics modulation leads to the change in the average parameters of the two-frequency model of the Earth pole oscillations. A method is proposed for detecting this effect by analyzing the phase variations of the observed Earth pole's modulation.