Summertime bottom water transports in the Bohai Strait, China

Abstract

The bottom water transports through the Bohai Strait influence the hydrographical conditions in the Bohai Sea. The summertime bottom circulation in the Bohai Strait and consequent water transports were investigated using observational data and numerical simulations. The results indicated that the bottom circulation in the Bohai Strait formed a cyclonic gyre in summer. Driven by the bottom circulation, inflow of bottom water from the northern Yellow Sea to Bohai Sea was found in the northern and southern Bohai Strait, and outflow was in the central Bohai Strait. Bottom water from the Laotieshan Channel was transported westward along the 25 m isobath in the southern Bohai Sea. Direct northward bottom water transports from the Bohai Strait to Liaodong Bay were not found by either current observations or model results. In the coastal areas off the Liaodong Peninsula, significant shoreward cross-isobathic currents were observed. The cross-isobathic currents drove the cold bottom water to ascend along the sloping topography, and periodically cooled the coastal water. A prominent lagged correlation between the moored temperature records and coastal currents was detected. The correlation coefficient was 0.69 with the temperature lagging behind currents by 1.5 days, indicating that cooling effects was dominated mostly by the cross-isobathic currents.