Effects of Thermal Stratification and Wind Blowing on Hydrodynamics in the Bohai Sea with Notably Shallow Depths

The problem of water pollution has become more widespread and severe in Chinese estuarine and coastal areas, such as the Bohai Bay and the mouth of the Yangtze River. The Bohai Sea has experienced the highest increase of pollution levels caused by rapid economic development and discharge of land waste. In order to recover the ocean environment in the Bohai Sea, it is necessary to understand the hydrodynamics of the sea. The present study focuses on the evolution of thermal stratification and the dispersion processes as a result of river water from the Yellow River discharging into the Bohai Sea. A three-dimensional baroclinic flow model was applied to simulate the current system and the density field, using the NCEP/NCAR Reanalysis (available from the NOAA Climate Diagnostics Center) and JCOPE reanalysis data (Miyazawa and Yamagata, 2003) as a boundary condition. A long-term hindcast simulation for 2003 was carried out. This simulation makes the spatial variability of the density stratification clear in the Bohai Sea. Moreover, the detailed particulars of the behavior of suspended solids in the Yellow River water are investigated using a modified Lagrangian particle tracking method. The present model can predict well the distribution of high turbidity water mass which can be seen in the southwestern sea area in the Laizhou Bay in Landsat satellite images. Wind effects on the sediment distribution were evaluated.