The numerical study of the South China Sea upper circulation characteristics and its dynamic mechanism, in winter

A coupled single-layer/two-layer model is used to study the South China Sea (SCS) upper circulation characteristics and its dynamic mechanism, in winter. The conclusions reached by the research are: (i) the effect of the Kuroshio on the upper circulation to the north of Dongsha Islands seems to be important in the northern SCS, there is a cyclonic gyre with three anticyclonic eddies, two of them to the north and southwest of Dongsha Islands respectively, and one in the northwestern Luzon Island; (ii) it is mainly a wind-driven current which exists to the south of Dongsha Islands—the water from alongshore of western Guangdong is driven by the northeast monsoon, then flows southward along the western SCS boundary, thus forming a rather strong western boundary current; and (iii) in the southern SCS, due to the actions of β effect and bottom topographic effect of the continental shelf to the south of Beikang Shoals, an anticyclonic eddy is formed periodically over the Nansha Trough, which grows and spreads westward, then dissipates in the western boundary, with around a 50-day period.