Baroclinic and barotropic tides in the Ross Sea

Abstract

The barotropic and baroclinic tides in the Ross Sea were simulated using a primitive equation, sigma-coordinate model, the Regional Ocean Model System (ROMS), for four tidal constituents, M₂, S₂, K₁, and O₁. Small elevation amplitudes were predicted over most of the basin, with a combined standard deviation of 30–50 cm. Larger amplitudes, with standard deviations ranging from 50–70 cm, occurred deep within the ice shelf cavity, over the continental slope, and over Iselin Bank. Most of the elevation response was associated with the diurnal constituents (K₁ and O₁), as was most of the depth-independent (barotropic) velocity response. Baroclinic tides were generated at locations of steep topography for the semidiurnal constituents, but not the diurnal. Diurnal continental shelf waves were generated by the diurnal tides and found to amplify the semidiurnal elevations and baroclinic tidal velocities over the continental slope. Comparisons with observations in both elevation and velocities showed very good agreement for the semidiurnal constituents (M₂ and S₂) and moderate agreement for the diurnal constituents (K₁ and O₁). The disagreement for the diurnal constituents was associated with diurnal frequency continental shelf waves, which were overexcited along the shelf break. The baroclinic tides induced both small-scale horizontal and vertical shear in the velocity fields in the Ross Sea.