Model of Oscillations of Earth’s Poles Based on Gravitational Tides

A model of oscillations of Earth’s poles is constructed on the basis of the analysis of the gravitational torques from Sun and Moon. The model reflects physical processes and does not imply using curve fitting techniques, based, for example, on the polynomial approximation. Within the framework of this model, the Chandler frequency is interpreted as the fundamental frequency of oscillations of the mechanical system and the annual frequency as the frequency of the excitation force. A fine mechanism of excitation of the oscillations based on the combination of natural and forced frequencies is revealed. The model has only six parameters that can be identified by applying the least squares technique to the experimental data of the International Earth Rotation and Reference Systems Service. The prediction provided by the proposed model has high degree of accuracy for an interval of several years.