Modelling of the barotropic processes in the Bohai Sea

The barotropic processes of tides, tidal currents, wind-driven currents and the interaction of winds and tides in the Bohai Sea are investigated with a three-dimensional shelf sea model.The tides and tidal currents are well simulated.The main characteristics of tides and tidal currents, such as the types of tides and tidal currents, co-tidal and co-range charts, co-current charts, tidal ellipses, mean tidal currents and tidal residual currents are presented.A pair of cyclonic and anticyclonic headland eddies in the northern Bohai Straits is discovered.The tidal currents have little vertical structure except close to the sea bottom.Driven by strong winds, the currents have a significant three-dimensional structure.In response to coastal geometry and bottom friction, the wind drift in the upper layers is in the direction of the wind or slightly to the right.In depth, considerable compensating currents maintain a circulation balance.The interaction of winds and tides is locally strong.The oscillating tidal currents play a role of dissipating energy.Thus the usual purely wind-driven currents in the area of weak residual tidal currents are often overestimated in the absence of tides.