北部湾冬夏季环流及其水交换的数值模拟研究

发布时间：2018-02-27 18:38

本文关键词： 北部湾环流水交换　出处：《中国海洋大学》2014年硕士论文　论文类型：学位论文

【摘要】：北部湾位于我国南海的西北部，介于16°~22°N，105°30′~110°E之间，为天然半封闭浅水海湾，它东接雷州半岛和海南岛，北依广西，西临越南，南与南海相通，平均水深为38m，最大水深为106m，水域面积约12.8×104km2。因其沿岸众多的河流，独特的地理位置，北部湾形成了由河口生态系统、海湾生态系统组成的独特自然环境。研究北部湾的环流规律以及北部湾海域的水交换程度从理论意义上说可以更好地了解北部湾的动力机制及物理自净能力，从实用意义上说能够协助更好地开发利用北部湾的自然环境、生态环境，为北部湾海域环境的保护提供科学依据和技术支持。本文以北部湾为研究对象，运用FVCOM三维水动力模型数值模拟了北部湾冬夏季的风生潮致环流，同时利用Tracer-Tracking模块，对北部湾的水交换规律进行了研究。主要工作内容和结果如下： 1.应用FVCOM模式，建立了北部湾三维水动力模型，通过湾内一个验证点连续九天的潮流潮位实测验证资料，以及绘制同潮时线和等振幅线图同前人的研究结果进行比对，验证了该模式模拟结果的正确性。同时得到以下结论：（1）潮波由湾口向湾内传播，振幅在北部湾顶部达到最大。其中全日分潮K1，O1在北部湾起主要作用。K1分潮振幅的最大值超过90cm，O1分潮振幅的最大值在100cm以上。O1和K1分潮的迟角均在越南顺化附近形成一个无潮点，同潮时线沿无潮点逆时针旋转。北部湾的M2，S2分潮的振幅明显小于全日分潮。M2和S2分潮的迟角由湾口向湾顶传播，不断增大。（2）北部湾的潮流形式主要为往复流，方向基本与岸线一致。雷州半岛西侧附近海域，海水流向与岸线较一致；北部湾北纬20°以南海域，从北向南，潮流的流向从东北-西南向逐渐转成西北-东南向。流速上看，琼州海峡西出口处流速最大，其次为海南岛西南侧近岸海域。（3）潮致余流在海南岛西北向和海南岛莺歌咀附近各形成一个闭合的逆时针环流。潮致余流从琼州海峡流入北部湾，沿广西沿岸，而后向南流动，一部分与沿海南岛向北流动的流形成一个逆时针环流，另一部分向西而后向南流动，在莺歌咀附近形成了一个小的逆时针闭合环流。 2.根据The National Centers for Environmental Prediction (NCEP)提供的冬夏季月平均风场数据，本文在FVCOM水动力模型的基础上，加入了冬夏季风场作为驱动条件，对北部湾冬夏季的风生潮致环流进行数值模拟。计算结果如下：（1）冬季北部湾的越南沿岸存在一个狭长的逆时针闭合环流。表层环流从琼州海峡自东向西流入北部湾，分别向北、西、西北沿广西、越南沿岸流动，还有一部分外海水从海南岛南部流入湾内，向西北方向流动，与越南沿岸的东南向流相互作用，形成一个狭长的闭合逆时针环流。中层与表层环流结构有明显区别，底层与中层环流结构基本一致。（2）夏季表层环流依然是自东向西经琼州海峡流入北部湾，在北部湾内形成了两个逆时针环流。海南岛西侧沿岸流向北流动，在北纬19°，，东经108°左右形成一个不闭合的逆时针环流。北纬19°附近有一支明显向东流动的环流，沿海南岛南岸流出北部湾，并且在北部湾南出口附近形成了一个顺时针旋转的环流。中层闭合环流的位置发生了偏移，底层与中层环流结构一致。 3.本文以雷州半岛西南侧新地村——海南省澄迈县马村港，海南省南侧三亚——越南岘港为界，通过示踪物方法，数值模拟了北部湾水交换情况，计算出北部湾的半交换时间和平均存留时间。结论如下：冬季北部湾平均存留时间为430天，夏季北部湾平均存留时间为588天。冬夏季北部湾水交换的相同点在于，水交换能力自水交换边界向湾内逐渐减弱，距水交换边界越近，水交换能力越强，反之，水交换能力越弱。不同点在于，湾内水交换平均存留时间的分布有着显著的不同。
[Abstract]:The Beibu Gulf is located in the north - west of the South China Sea , between 16 掳 ~ 22 掳 N , 105 掳 30 ' ~ 110 掳 E . It is a natural semi - enclosed shallow water bay . It is a unique natural environment consisting of estuary ecosystem and Gulf ecosystem . 1 . The model of the three - dimensional hydrodynamic model in Beibu Gulf is established by applying the model of the model , and the correctness of the simulation results is verified by comparing the measured data of tidal current at one point in the bay for nine consecutive days . ( 1 ) The tidal wave propagates from the bay mouth to the bay , and the amplitude reaches the maximum at the top of the Beibu Gulf . ( 2 ) The tidal current form of Beibu Gulf is mainly the reciprocating flow , the direction is basically the same as that of the coastline . The flow direction of the sea area near the west side of the Leizhou Peninsula is consistent with the coastline ; the flow direction from the north to the south and the tidal current flows from the northeast to the southeast to the southeast to the southeast . ( 3 ) The tidal residual flow forms a closed anti - clockwise circulation in the northwest of Hainan Island and Yinggezui , Hainan Island . 2 . Based on the water power model of winter and summer provided by The National Centers for Environmental Prediction ( NCEP ) , this paper adds the winter summer monsoon field as the driving condition on the basis of the water power model of the model . The numerical simulation is carried out on the circulation of wind - induced tide in the winter and summer of Beibu Gulf . The results are as follows : ( 1 ) There is a narrow and counterclockwise closed circulation along the Vietnamese coast in Beibu Gulf in winter . The surface circulation flows from east to west to Beibu Gulf from east to west , and flows along the coast of Guangxi and Vietnam respectively . Some of the outer seawater flows from the south of Hainan Island to the Gulf . It also flows in the northwest direction . It forms a long and closed anti - clockwise circulation . The middle layer and the surface circulation structure are obviously different , and the bottom layer is basically consistent with the middle layer circulation structure . ( 2 ) The surface circulation in summer is still flowing from east to west to Beibu Gulf through the Qionghai Strait . Two anticlockwise circulation is formed in Beibu Gulf . There is an unclosed anti - clockwise circulation around the west coast of Hainan Island . There is a circulation around the south bank of Hainan Island , which flows out of the Beibu Gulf , along the south bank of Hainan Island , and a clockwise rotating circulation is formed near the south exit of the Beibu Gulf . The position of the middle closed loop is offset , and the bottom layer is consistent with the middle layer circulation structure . 3 . According to the method of tracer , the water exchange in Beibu Gulf is simulated by means of tracer method , and the half - exchange time and average residence time of Beibu Gulf are calculated . The conclusion is as follows : The average residence time of Beibu Gulf in winter is 430 days . The average residence time of Beibu Gulf in summer is 588 days . In winter and summer , the water exchange capacity gradually decreases from the water exchange boundary to the bay , the closer the water exchange boundary is , the stronger the water exchange capacity , and the weaker the water exchange capacity . The difference lies in that the distribution of the average residence time of the water exchange in the bay is significantly different .

【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P731.27

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