Numerical study of the circulation and water transport in Beibu Gulf: A short communication

Abstract

The Beibu Gulf, located in the northwestern South China Sea, is rich in oceanic energy and biological resources. Based on the FVCOM model, a three-dimensional numerical model was adopted in the study, which was validated with the observation data. The results show that Beibu Gulf is a typical diurnal tidal area. The K1 and O1 tide have an amphidromic point near Hue, Vietnam, forming a rotary tidal system. From the amphidromic point, the amplitudes increase gradually, eventually reaching more than 80 cm and 100 cm, respectively. The maximum amplitudes of M2 and S2 tide are about 70 cm and 10 cm, respectively. Meanwhile the tidal current presents a typical rectilinear flow in Beibu Gulf, with strong the diurnal tidal currents. Seasonal changes in the circulation structure of Beibu Gulf are obvious. The Beibu Gulf is generally controlled by a non-closed anticlockwise circulation in winter. In summer, there are two counterclockwise eddies. The tidal residual current flowing through Qiongzhou Strait goes west all year round, with the largest average flow flux of 0.07 Sv in winter. Based on DYE module from FVCOM, pollutants from the Pearl River Estuary pass through Qiongzhou Strait, and reach Weizhou Island after 109 days. This is of great significance to the monitoring and control of red tide, and the protection of marine ecological environment in Beibu Gulf.