Application of FVCOM in numerical simulation of tide and tidal currents in the northern South China Sea

A high resolution hydrodynamic model was established using an unstructured triangular grid,FVCOM(finite-volume coastal ocean model)to study the tides and tidal currents of the northern South China Sea.The simulation results were in good agreement with observation data. According to the simulation results, the tidal and tidal currents characteristics of M2, S2, K1, O1 was analyzed. With the application of high resolution triangular gird, the characteristics of tide and tidal currents around the Dongsha Islands were computed exactly and analyzed in detail. The simulated tidal constituents were more accurate than previous study. The results showed that the areas between the Shenquan Port and the Jiazi Port were dominated by regular diurnal tide and the Zhujiang River Estuary was expressed irregular semi-diurnal tide. The tidal characteristic of other areas were irregular diurnal tide.The continental shelf area was dominated by rectilinear, while the area near continental slope was characterized by strong rotary current. The shelf break area is the boundary between irregular diurnal and irregular semi-diurnal tidal currents. Dongsha areas were dominated by irregular diurnal tidal currents in which the currents rotate clockwise.The distributions of the maximum possible current velocities were paralleled with the depth. The possible velocity was especially high around the Dongsha Islands and the maximum velocity could reach 70 cm/s near the Taiwan Strait. For the northern South China Sea, the tidal motion was maintained by the ocean tides from the the Bashi Channel, which were divided into three different forms out of the northern South China Sea; The maximum residual current appeared on the west of the Taiwan Strait, which flowed into the Taiwan Strait from south to north at a speed of 6 cm/s. The coastal residual current flowed along the China Shore from east to west.