Study on short-range numerical forecasting of ocean current in the East China Sea Ⅱ. Three-dimensional diagnostic model and its application in the Bohai Sea

In this paper, a three-dimensional (3-D) baroclinic diagnostic model for short-range numerical forecast is proposed to calculate the monthly averaged flow field in the Bohai Sea.By using the model and monthly averaged temperature and salinity data, monthly barotropic and baroclinic flow field are calculated, and 2-D and 3-D characteristics of flow are described and demonstrated.On the basis of the analysis of the modelling results and the observed temperature, salinity and wind data, the monthly and seasonal characteristics and generation mechanism of circulation in the Bohai Sea are also discussed.It is pointed out in this paper that in spring and autumn, the monthly averaged flow fields are not representative, for the wind direction varies in a wide range and the averaged wind field is much weaker than the instantaneous one.These results show the reliability of the model for describing the monthly characteristics in numerical forecast of nrran current.