Numerical Simulations of Baroclinic Tide Fields in the Global Ocean: Estimation of Baroclinic Tide Energy Available for Deep Ocean Mixing (Workshop on Nonlinear Water Waves)

Abstract

The global distributions of the major semidiurnal (M_{2} and S_{2}) and diurnal (K_{1} and O_{1}) baroclinic tide energy are investigated usin g a hydrostatic numerical model. A series of numerical simulations using various horizontal grid spacing of Delta x=1/5^{circ}-1/20^{circ} shows that generation of energetic baroclinic tides is restricted over prominent topographic features. It is also found that the energy conversion rate from barotropic to baroclinic tide is very sensitive to horizontal grid spacing as well as the resolution of the model bottom topography. Extrapolating the calculated results to the limit of zero horizontal grid spacin g(Delta x=0^{circ}) yields the estimate of the global baroclinic conversion rate to be 1240 GW. The amount of baroclinic tide energy dissipated in the open ocean below a depth of 1000m (the typical depth of the main thermocline) is estimated to be 560-680 GW, which is comparable to the mixing energy estimated by Webb and Sughinohara (2001) as needed to sustain the global thermohaline circulation.