The oceans and the Earth's rotation

In the long run, the tidal interaction between the Moon and the solid Earth is mediated by the oceans. It produces the retardation of the Earth's rotation known as ‘tidal friction’. Due to the changing configuration of the continents, it is a non-monotonic function of time. Tides of the solid Earth dominate the short-periodic tidal effects while the exchange with the atmosphere is preponderant in climatic changes, especially with an annual signature. It is shown that the influences of the oceans within such short time-scales must be taken into account for tidal and for non-tidal variations as well if one wants to model the Earth's rotation at the cm-level corresponding to the most advanced observational techniques.