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近50年来,由于观测数据的局限和数值模型多为诊断计算,北部湾夏季环流结构与生成机制存在较多争议.为此,本文在南海西北部构建了三维后报模型,充分考虑了日平均的风场、热通量和侧边界强迫,以及考虑沿岸八大河流和潮汐的作用,并把东边界远离琼州海峡.本文的模式结果不仅与我国近海海洋综合调查与评价专项的同步观测数据吻合较好,而且与历史观测数据做到了相互验证,从而揭示了北部湾夏季环流结构:南部为反气旋式涡旋控制,北部环流呈气旋式弯曲.虽然北部湾夏季环流的主结构较为稳定,但环流强度及控制范围具有一定的年际和月周期振荡特征.垂向上,表层环流与温跃层以下的环流结构有所差别.通过3个敏感性实验,发现夏季北部湾南部环流主要受南海环流控制,而北部受季风控制.通过位涡收支分析,进一步发现北部湾北部的气旋式环流为正的风应力旋度驱动.另外,湾西岸的河流注入使得红河口外的垂向环流分布呈现两层结构.总的来讲,夏季环流结构和生成机制的揭示有助于海洋地球化学和海洋渔业等学科在北部湾的进一步研究.
In the past 50 years, due to the limitations of the observed data and the numerical models mostly diagnosed, there is much controversy over the summer circulation structure and genesis mechanism in the Beibu Gulf.Therefore, this paper constructs a three-dimensional model of the aftercast in the northwestern South China Sea, taking full account of the daily average Wind field, heat flux and lateral boundary forces, as well as taking into account the effects of the eight major rivers and tides along the coast and keeping the east boundary away from the Qiongzhou Strait.The model results in this paper are not only in agreement with the simultaneous observational data of China’s comprehensive offshore marine survey and evaluation Good, but also with the historical observation data to verify each other, thus revealing the Beibu Gulf summer circulation structure: the southern anti-cyclonic vortex control, the northern circulation was cyclonic bending.Although the Beibu Gulf summer main circulation structure is relatively stable, but the circulation The intensity and control range have some interannual and monthly periodic oscillations.Directionally, the surface circulation is different from the circulation structure below the thermocline.Through three sensitivity experiments, it is found that the circulation in the south of the northern Beibu Gulf is mainly controlled by the South China Sea , While the northern part is controlled by the monsoon.According to the eddy-current income and expenditure analysis, it is further found that the cyclonic circulation in the northern Beibu Gulf is a positive wind In addition, the vertical distribution of circulation outside the mouth of the Red River has a two-layer structure due to the river injection into the west bank of the Gulf.In general, the revelation of summer circulation structure and genesis mechanism is of great help in the discipline of marine geochemistry and marine fisheries North Bay for further research.