ABSTRACT A three-dimensional numerical model of the Yellow Sea and the East China Sea has been developed to investigate the M2 tidal current distribution, especially the vertical variation of the horizontal current in the region. Results have been compared with current meter data acquired from AMTEX-75 and recent joint USA-China Marine Sedimentation Dynamics Study Program. Some of the preliminary results are presented and discussed.
INTRODUCTION The three-dimensional hydrodynamical numerical model has a grid resolution of 1/5 latitude by 1/4 longitude and covers the entire Yellow Sea and the East China Sea continental shelf. This is the same grid system as that used in the two-dimensional shelf model of Choi (1980). The hydrodynamic equations used in the model are linear with the exception of a quadratic bottom friction. Solutions are obtained by the Galerkin method with an expansion of currents through the vertical water column in terms of simple cosine function. The numerical techniques are based on modeling efforts at the Bidston Observatory (Heaps, 1972; Davies, 1980). As a first attempt, the developed model was utilized to reproduce the three-dimensional current structure of the M2 tide representing the dominant tidal condition of the region. The computed results were compared with the current measurements from the. Air Mass Transformation Experiment in 1975 (AMTEX-75) (Trump and Burt, 1981) and from the USA-China Marine Sedimentation Dynamics Study (Larsen and Cannon, 1983). A reasonable agreement was found between the observations and model results thus supporting validity of the computed distribution of the M2 tidal currents in the region.
NUMERICAL MODEL The equations of continuity and the equations motion for homogeneous water neglecting nonlinear terms, shear in the horizontal and the direct influence of the tide-generating potentials, may be written in spherical polar coordinates as; (Formulas are shown in the paper)