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.

关于北部湾环流与水输运的数值研究

中文摘要：北部湾位于中国南海西北部，拥有丰富的海洋能源和生物资源。在FVCOM模型的基础上，研究采用了三维数值模型，并用观测数据进行了验证。结果表明，北部湾是一个典型的昼夜潮汐区。K₁和O₁潮汐在越南顺化附近有一个双色点，形成一个旋转潮汐系统。从两极点开始，振幅逐渐增大，最终分别达到80厘米和100厘米以上。M₂和S₂潮汐的最大振幅分别约为70厘米和10厘米。同时，北部湾的潮汐流呈现出典型的直线型流动，日间潮汐流动强烈。北部湾环流结构的季节性变化十分明显。北部湾在冬季一般由非封闭的逆时针环流控制。在夏季，有两个逆时针漩涡。流经琼州海峡的潮汐余流常年向西流动，冬季最大的平均流量为0.07Sv。根据FVCOM的DYE模块，珠江口的污染物通过琼州海峡，109天后到达涠洲岛。这对监测和控制赤潮，保护北部湾的海洋生态环境具有重要意义。