| 摘要: |
| 针对整个渤海海域悬浮泥沙季节变化及其影响机制的数值研究相对缺乏且机制尚不清晰, 基于ROMS三维海洋模型对渤海海域水动力环境与悬沙分布开展数值模拟。模拟结果显示, 渤海海峡环流终年“北进南出”, 夏季环流明显强于冬季, 并呈现外围逆时针环、内部顺时针环的“双环”结构。渤海中部海域在夏季存在明显的温跃层现象, 其强度分布与等深线较为一致, 温跃层在4月开始形成, 7月最强。渤海表层悬沙分布具有显著的季节变化, 冬季悬沙浓度最大, 秋季次之, 春季再次之, 夏季最小。控制悬沙浓度的波流底切应力在秋冬季节较大, 春夏相对较小, 且流致切应力始终在波流切应力中占主导地位。秦皇岛海域悬沙浓度常年偏低的主要原因是位于M2无潮点附近, 属于弱潮流区, 底层流速相对较小, 底部沉积物发生再悬浮概率较小。夏季温跃层的存在在一定程度上减小了底边界层流速, 增大了流速的垂向梯度, 对底部悬浮泥沙的向上扩散有明显的抑制作用。因此, 温跃层的存在是造成夏季表层悬沙浓度最低的重要原因。 |
| 关键词: ROMS模型 渤海 温跃层 表层悬沙浓度 季节变化 |
| DOI：10.11693/hyhz20221200322 |
| 分类号:P734.2+3 |
| 基金项目:中国科学院科研仪器设备研制项目, YJKYYQ20190047号。 |
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| NUMERICAL STUDY ON SEASONAL DISTRIBUTION OF SURFACE SUSPENDED SEDIMENT IN THE BOHAI SEA AND THE CONTROLLING FACTORS |
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ZHANG De-Qiang1,2, PANG Chong-Guang1,3,4, WANG Yan-Ping5,6, CHEN Xiang-Jian1,7
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1.Key Laboratory of Ocean Circulation and Waves, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;2.University of the Chinese Academy of Sciences, Beijing 100049, China;3.Laboratory for Ocean and Climate Dynamics, Laoshan Laboratory, Qingdao 266237, China;4.Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao 266071, China;5.Beijing Institute of Applied Meteorology, Beijing 100029, China;6.State Key Laboratory of Geo-information Engineering, Xi'an 710054, China;7.School of Mathematics and Systems Science, Shandong University of Science and Technology, Qingdao 266590, China
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| Abstract: |
| Due to the lack of research on the numerical simulation of suspended sediment distribution in the whole Bohai Sea, the hydrodynamic environment and the distribution of suspended sediment concentration in the Bohai Sea was numerically simulated in the three-dimensional ocean model ROMS (regional ocean modeling system). Results show that the Bohai Strait circulation presents a “north in south out” pattern all year round. The circulation in summer is obviously stronger than that in winter, and presents a “double-ring” structure with an outer counterclockwise ring and an inner clockwise ring. There is a strong thermocline in the middle of the Bohai Sea in summer, and the distribution of its strength is close to the isobath. The thermocline begins to form in April and is the strongest in July. The distribution of surface suspended sediment concentration in the Bohai Sea has distinct seasonal change, with the highest concentration in winter, followed by autumn, spring, and summer. The wave-current bottom shear stress controlling suspended sediment concentration is larger in autumn and winter, but smaller in spring and summer, and the current-induced shear stress always plays a dominant role in wave-current shear stress. The main reason why suspended sediment concentration off the Qinhuangdao is low all the year round is that the current velocity at the bottom is relatively small, resulting in the weak sediment resuspension, as the location is adjacent to an amphidromic point of the M2 tidal constituent. The thermocline in spring and summer reduces the current velocity at the bottom boundary layer, and increases the vertical gradient of the velocity to a certain extent, and further suppresses the upward diffusion of the bottom sediment. Therefore, the existence of thermocline is one of the controlling factors of the lowest surface suspended sediment concentration in summer. |
| Key words: ROMS (regional ocean modeling system) the Bohai Sea thermocline surface suspended sediment concentration seasonal variation |
