Numerical simulation of tides and three-dimensional tidal currents in Jiaozhou Bay by a movable land-sea boundary model

A numerical model suitable for tides and tidal currents forecast in Jiaozhou Bay,which includes M₂,S₂,K₁,O₁,M₄,and MS₄ tidal constituents,is developed based on Princeton Ocean Model (POM) of 98 wersion.A wetting and drying scheme is imbedded into POM to deal with the dynamic land-sea boundaries in Jiaozhou Bay,where extensive mudflats are regularly exposed from extremely shallow coastal waters.Hourly tidal level observations of Dagang gauge in a month and the diel consecutive insitu tidal current data at 5 stations are used to validate the model performance.Comparisons between observations and numerical modeling indicate that the model performs well in simulating the tidal dynamics in Jiaozhou Bay.The distributions of tides,tidal currents,and Eulerian residual currents are given by the model;the modeled cyclic tidal currents and vortex patterns in Eulerian residual currents field are consistent with observations.The propagation of tidal waves is discussed based on tidal energy flux computation.The tides in Jiaozhou Bay is discovered to be characterized by standing waves to a great extent,which can be manifested by the analyses of tidal level and currents evolution,as well as the tidal energy fluxes distribution.Numerical experiments show that the moving boundary treatment is important for the numerical simulation of tidal current speed in Jiaozhou Bay.It is necessary to utilize a model which has movable land-sea boundaries to treat the wetting and drying processes in order to precisely predict the tidal currents in coastal waters with wide intertidal zones.