PERIODIC CHANGES OF THE ANGULAR-MOMENTUM BUDGET DUE TO THE TIDES OF THE WORLD OCEAN

The tides of the world ocean are investigated with respect to their instantaneous angular momentum budgets. The most important semidiurnal (M2, S2, N2), diurnal (K1, O1, P1), and long-period tides (Mf, mf, Mm, Ssa) have been simulated with a numerical model of the classical, unconstrained type where the effects of loading and self-attraction are considered in a parametrized form. On the whole, the calculated oscillation systems agree very well with observations and results from other tidal models. With increasing period, the long-period tides approach the equilibrium state, to which the semiannual tide is very close. The angular momentum budgets are analyzed, where especially the characteristics of each tidal band are identified. A common feature of all partial tides is the dominance of the pressure torque in the angular momentum balances. This torque, representing topographic coupling in the ocean-solid earth system, is thus the only relevant mechanism to exchange angular momentum between hydrosphere and lithosphere. The quantities that enter the excitation functions are given, and the resulting theoretical fluctuations in the Earth's rotation are briefly discussed, details being presented in future studies.