Tide model evaluation under different conditions

A three-dimensional baroclinic shelf sea model is employed to evaluate the precision of the predicted tidal harmonic constants under different conditions in the South China Sea (SCS). Several numerical experiments, including different model dimensions (two-dimension or three-dimension), prescribed open boundary conditions (without or with mean sea surface elevation), astronomical tidal forcing, stratifications (without or with baroclinic effect) and wind forcing, are carried out. The resulted time series of surface elevation data are stored to yield harmonic constants for the four most significant constituents, M2, S2, K1 and O1, and the computed harmonic constants are compared with the observed ones. It is shown that the predicted tidal harmonic constants by the three-dimensional model are better than those by the two-dimensional one; with astronomical tidal forcing and mean sea surface elevation at the open boundary, the predicted accuracy could be improved and it is recommended that the baroclinic effect and wind forcing are also included in the modeling. The tidal energy fluxes through each SCS open boundary and into the Gulf of Tonkin and Gulf of Thailand are also estimated.