Ocean tidal excitation of polar motion

An investigation was conducted to ascertain the response of the rotational motion of the earth to forcing functions produced by the water mass redistribution due to the ocean tides. In particular, the components of displacement of the rotation axis at the surface of the Earth were obtained. The investigation also addressed the larger question concerning the possibility of excitation of the Chandler wobble of the earth. In general, the results show the existence of a polar wobble as a response to each of the components of the ocean tides. The magnitude of the polar displacement depends on two factors: the amplitude of the tidal component and its period. The maximum periodic contributions are: the Doodson's component number 055.565 with a period of 18.613 years and 50 cm of polar displacement, the annual component 056.544 with 37 cm of polar displacement and the semi-annual 057.555 with 32 cm. The tidal components with daily and semi-daily periods yield very small polar displacements of the order of 0.01 cm. The combined effect of all the periodic components can yield as much as 90 cm of pole displacements. The changes produced by the ocean tides in the products of inertia are periodic and regular, therefore, they cannot be the source of excitation of the Chandler wobble.