A THREE-DIMENSIONAL HYDRODYNAMIC SIMULATION IN THE OFFSHORE NEAR THE CHANGJIANG ESTUARY——A CASE STUDY COMPARED WITH OBSERVATIONS

Base on ECOMSED model,a three-dimensional hydrodynamic model is developed in the offshore area near the Changjiang Estuary in the East China Sea.This model is driven by tide and wind,as well as inflow and outflow currents such as Kuroshio,Changjiang runoff.The hor- izontal resolution is 1/20°.There have 11 layers on the vertical direction.The numerical results of 4 main constituents of tide(M_2,S_2,K_1,O_1)and currents are in good agreement with observation data.Compared with 20 gauge stations,the mean absolute error between the calculated M_2 tidal amplitude and the observed ones is only 6.72cm;the mean absolute error of phased-lag is 5.23°.For S_2,the mean absolute errors of amplitude and phased-lag are 3.67cm and 7.21°, respectively.The mean absolute errors of amplitude and phased-lag for K_1 are 3.25cm and 6.63°For O_1,the mean absolute error of calculation and observation is relatively small,amplitude is 2.42cm and phased-lag is 4.67°.The numerical results of current are also compared with observation data measured during Aug.,2006 in the East China Sea.The correlation coefficients of current between simulation and observation are greater than 0.75 generally.The three-dimensional hydrodynamic model developed by this paper can well describe the characters of elevation and current in the offshore near the Changjiang Estuary and can be used as hydrodynamic background to simulate the suspend sediment transport in this sea area.