Fine grid tidal modeling of the Yellow and East China Seas

A fine grid tidal modeling experiment is carried out in order to investigate the tidal regimes for major five tidal constituents, the nonlinear tidal phenomena in terms of M4 and MS4 generation, and the independent tide by the tide generating force in the Yellow and East China Seas (YECS). In this study a two-dimensional numerical model based upon a subgrid-scale (SGS) stress modeling technique is used with the tide generating force included. The model was validated with recently observed tide and current data. The calculated tidal charts for tidal elevation show a generally good agreement with existing ones, with more accurate feature of the M2 cotidal chart in comparison with both the observed data and the existing tidal charts. A careful comparison of the computed diurnal amplitude with observations suggests that the diurnal constituents seem to be overdamped especially in the Kyunggi Bay region, for the case when quadratic bottom friction law is used. ation features of the M4(MS4) tides are discussed in the YECS, based upon the analyses of the observed and calculated results. The amphidromic system of the M4 is quite complicated and one noticeable characteristic is that the propagation direction of the M4 tidal wave along the west coast of Korean peninsula is opposite to that of the M2 tidal wave. This result coincides with observations. The propagation feature of the MS4 is almost similar to that of the M4, but with lesser amplitude. The responses of the M4 tidal features to momentum diffusion term and depth-dependent form of the friction coefficient are also discussed. also shown that when the independent tide (Defant, 1960) arising from tide generating force (TGF) coexists with tidal waves (co-oscillating tide) arising from external boundary forcing, the TGF tidal waves are dissipated and their amphidromes tend to move westward. This may be interpreted as a process whereby the incident and reflected TGF tidal waves are damped by co-oscillating tide arising from external force at open boundaries. The TGF amplitude is found to be up to 10 cm and 4 cm in the Kyunggi Bay for the M2 and S2 constituents while those for all diurnal constituents are less than 1 cm over the entire model domain.