NUMERICAL SIMULATION OF THE THERMOCLINE UNDULATION IN THE NORTH YELLOW SEA UNDER THE EFFECT OF TIDE

Besides the seasonal variation, the instantaneous wave of thermocline may occur under the effects of tide, wind mixing and rainfall,etc. In this paper, the numerical simulation has been carried out for the fluctuation and the undulation of thermal layer under the influence of tide (simultaneous input 4 principal tidal components, such as M 2,S 2,K 1,O 1) by using three\|dimensional nonlinear model (in the vertical direction,the sea is separated into three layers,such as the upper mixed layer,the thermal layer and the lower mixed layer).The result shows that the wave of the thermocline is consistent with the observations. The distribution of undulation of the thermal layer is given and the temporal spatial variation characteristics of the thermocline undulation are also analyzed. Although the wave of the thermal layer and tide are related to each other in a certain degree,but they are different in the phase, amplitude and even period. Meanwhile, the waves in the upper and lower surface of thermocline are also different in the phase, amplitude and period in many positions.In the middle and lower layer,the mean current possesses almost the same direction and magnitude. The waves of large amplitude always occur in the sea areas with a convex coastline and complex variation of depth.It may be possible that the causes are the bottom friction and complex geography.