DYNAMIC PROCESS OF VERTICAL CIRCULATION AND TEMPERATURE-SALINITY STRUCTURES IN COASTAL AREA OF EAST CHIAN SEA II. THE STRUCTURE OF THE WATER TEMPERATURE AND SALINITY

In the last paper (Liu et al,2004), authors have discussed significance, contents and method on this study and the simulated results of the vertical circulation. In this paper, we analyze the simulated results of the water temperature and salinity. Numerical simulation results of the water temperature and salinity in the coastal area of the East China Sea demonstrated different distribution characteristics in wintertime and summertime. In wintertime, water temperature and salinity are low and uniform vertically in near shore, high and stratifies in the offside sea. In the offside sea, the water temperature is high in the surface layer, low in the bottom layer, and the salinity is high in the surface and bottom layers, low slightly in the mid-layer and gradually become high from the near shore to the offside sea. A slightly low salinity water tongue forms below the near surface layer of the southern area of the Changjiang mouth and spreads to the offside sea from the near shore. The stronger thermocline and halocline form in the Changjiang diluted water area and in the near surface layer of the offside sea of the northern and southern of the Changjiang mouth. The water temperature and salinity distributions are uniform in the bottom layer of the offside sea, characterized by low temperature and high salinity. With lowering of the latitude, increasing of the continental slope and the water depth and enhancing of the coastal downwelling from the north to the south, the vertical uniform distribution widths of the water temperature and salinity in the near shore become narrow gradually. The thermocline and halocline intensities of the Changjiang diluted water area strengthen gradually from the north to the Changjiang mouth, and weaken gradually from the Changjiang mouth to the south. The thermocline and halocline intensities in the near surface layer of the offside sea weaken gradually from the north to the Changjiang mouth, and strengthen gradually from the Changjiang mouth to the south and shift upwards gradually from the north to the south. The halocline of the Changjiang diluted water area thickens due to the effect of the coastal downwelling. In summertime, the water temperature is high in the near shore and the offside sea, low off the near shore and the cold waters rise. The water temperature change is great between the surface layer and the bottom layer compared with that of the wintertime, and the stratification is more evident in the vertical direction. The salinity is low in the near shore, high in the offside sea, and the salinity change is small in subsurface layer of the offside sea of the Changjiang mouth and its southern part. The thermocline and halocline form in the Changjiang diluted water area and the subsurface layer of the offside sea of the southern of the Hangzhou Bay. Mixing layer occurs above the thermocline and halocline and characterized by high temperature and low salinity, the temperature and salinity are uniform below the thermocline and halocline and characterized by low temperature and high salinity. With increasing of the latitude, decreasing of the continental slope and the water depth, enhancing-weakening of the coastal upwelling from the south to the north, the thermocline and halocline intensities of the Changjiang diluted water area strengthen gradually from the south to the Changjiang mouth and weaken gradually from the Changjiang mouth to the north, whereas the thermocline and halocline intensities of the subsurface layer of the offside sea weaken gradually from the south to the Changjiang mouth and strengthen gradually from the Changjiang mouth to the north. The thermocline and halocline of the offside sea shift upwards gradually from the south to the north. The halocline of the Changjiang diluted water area thins due to the effect of the coastal upwelling.