Circulations associated with cold pools in the Bohai Sea on the Chinese continental shelf

Abstract Circulations associated with cold pools in the Bohai Sea were investigated in the summers of 1959 and 2006 using observations and numerical simulations. The climatological forcing was incorporated to drive a model based on the Regional Ocean Modeling Systems (ROMS) to reconstruct the monthly evolution of flow structure. Cold pools were found to be separated into two parts by an undersea ridge in the central Bohai Sea. A set of numerical experiments were conducted to evaluate the relative contributions from the exchange across the strait, heat flux, wind, and tides. Baroclinic circulation was the dominant component of the circulation. A basin-scale cyclonic gyre was the main feature during the stratified seasons from May through August. Cyclonic and anticyclonic sub-basin scale gyres emerged in late spring and peaked during July and early August, accompanied by intensifying frontal jets along the west and south coasts of the Bohai Sea. The cyclonic frontal jet in the model was responsible for rapid reduction of particles released from the surface layer of the Bohai Sea in summer; and 2) Experiments using Lagrangian particle tracking also showed that particles released in Liaodong and Bohai bays were retained longer than those released in the other regions as the surface convergence in the western Bohai Sea resulted in an intense concentration of particles.