Current and tide observations in the southern Yellow Sea

Determination of mean currents and tides are particularly difficult in coastal regions. Flows are often nongeostrophic and short lived. Bathymetry is frequently not adequately known and can greatly influence coastal dynamics. To better quantify tides and currents in the southern Yellow Sea, three pressure gauges and three acoustic Doppler current profilers (ADCPs) were bottom moored for 4-6 month intervals at depths ranging from 77 to 89 m. Tidal range is over 2 m, and maximum current velocities are between 50 and 80 cm/s at the mooring locations. The present data are analyzed for 13 significant tidal constituents which are found to account for similar to 85% of the sea surface height variability. M2 is the dominant constituent, followed by S2 and K1. Flow is dominated by the tides. Mean currents are relatively small, ranging from similar to 1.5 cm/s at the northern mooring to similar to 4 cm/s at the southern mooring. Delineations of barotropic and depth-dependent currents are made from the ADCP measurements in terms of mean and eddy kinetic energy. Currents are found to be most depth dependent in the near-surface layers. Approximately 85-90% of the eddy kinetic energy is depth independent.