The effect of ocean tides on the Earth's rotation as predicted by the results of an ocean tide model

Abstract

The published ocean tidal angular momentum results of Seiler [1991] are used to predict the effects of the most important semidiurnal ( M 2 , S 2 , N 2 ), diurnal ( K 1 , O 1 , P 1 ), and long period ( Mf , Mf′ , Mm , and Ssa ) ocean tides on the Earth's rotation. The separate, as well as combined, effects of ocean tidal currents and sea level height changes on the length‐of‐day, UT1, and polar motion are computed. The predicted polar motion results reported here account for the presence of the free core nutation and are given in terms of the motion (within the rotating, body‐fixed terrestrial reference frame) of the celestial ephemeris pole so that they can be compared directly to the results of observations. Outside the retrograde diurnal tidal band, the summed effect of the semidiurnal and diurnal ocean tides studied here predict peak‐to‐peak polar motion amplitudes as large as 2 mas. Within the retrograde diurnal tidal band, the resonant enhancement caused by the free core nutation leads to predicted polar motion (or, equivalently, nutation) amplitudes as large as 9 mas (at the unobservable retrograde K 1 tidal frequency).