||Some aspects of the ocean response to loading in the context of GRACE
Forcing by freshwater fluxes implies variable surface loads that are not treated in constant-volume ocean models. Under the assumption of an equilibrium response, such surface loads merely lead to bottom pressure fluctuations that have no dynamical significance and which can be computed directly from knowledge of the forcing loads. An ocean model forced by realistic freshwater fluxes is used to test the validity of the equilibrium assumption on seasonal to daily timescales. The simulated nonequilibrium signals have amplitudes much weaker than those of the forcing over the deep ocean, but stronger signals can be found in shallow and semi-enclosed coastal areas, where the equilibrium assumption can lead to substantial errors even at monthly and longer time scales. Forcing by mean seasonal river runoff yields similar results. Comparisons with results from atmospheric pressure loading indicate that nonequilibrium signals forced by freshwater fluxes can be important in some coastal tropical regions, and at relatively long timescales, for which forcing by freshwater flux is much stronger than by pressure. These and other modeling results exploring how the ocean responds to loading in general are discussed in the context of dealiasing and interpreting the GRACE data.