远区台风“三巴”对长江口波浪动力场的作用机制     

任剑波  何青  沈健  徐凡  郭磊城  谢卫明  朱磊 《海洋科学》2020,44(5):12-23

针对远区台风对河口波浪动力场的影响问题,利用第三代波浪模式SWAN计算了远区台风"三巴"期间长江口波浪动力场分布,分析了陆架至河口区的波浪能量耗散和波致泥沙侵蚀的时空分布,发现波浪由外海向近岸传播过程中,波-波相互作用导致能量由高频向低频转换,周期和波长逐渐增大,近底层轨道流速增大,能量密度增高;阐明白帽破碎是维持深水区波浪能量平衡和限制波高成长的主要机制,底摩擦耗能和水深诱导的破碎耗能是长江口横沙东滩和崇明东滩邻近海域波高衰减的主要原因;提出波浪产生的底部切应力与相对水深有关,当波浪传播到浅水区时,波长和周期越大,波浪切应力越大。研究揭示了与河口相距数百公里的远区台风能够对长江口波浪动力场产生明显影响,河口水下三角洲前缘是最容易受到波浪侵蚀的区域,研究成果弥补了目前关于陆架远区台风对河口波浪动力场影响研究的不足,对深化认识远区台风对长江口动力环境、地貌演变、航运安全和滩涂保护等有重要科学意义。  相似文献   

金衢盆地第四纪红土沉积粒度组成特征   总被引：4，自引：1，他引：4  

朱丽东  叶玮  周尚哲  李风全  杨立辉  沈叶琴 《海洋地质与第四纪地质》2006,26(4):111-116

浙江金衢盆地第四纪红土分布广泛,是开展红土与全球变化研究的理想场所之一。汤溪红土沉积剖面的粒度组成研究表明:砂(>63μm)含量极少,平均1.58%,粉砂(4~63μm)和黏粒(<4μm)为众数粒组,其含量的平均值分别为48.51%和49.91%,频率曲线呈双峰式,推测红土母质具风成特性,沉积后经历了较强的风化成壤作用;均质红土与网纹红土具有相似的粒度分布特征,但网纹红土的分选更为复杂,底部有近源物质的混入;汤溪红土粒度的纵向变化旋回和纵向变化趋势,可能指示了中更新世以来南方气候的不稳定性和气候逐渐变干冷的趋势。  相似文献   

Simulations of Annual Cycle of Phytoplankton Production and the Utilization of Nitrogen in the Yellow Sea     

Tian?TianEmail author  Hao?Wei  Jian?Su  Changsoo?Chung 《Journal of Oceanography》2005,61(2):343-357

A nutrient dynamic model coupled with a 3D physical model has been developed to study the annual cycle of phytoplankton production in the Yellow Sea. The biological model involves interactions between inorganic nitrogen (nitrate and ammonium), phosphate and phytoplankton biomass. The model successfully reproduces the main features of phytoplankton-nutrient variation and dynamics of production. 1. The well-mixed coastal water is characterized by high primary production, as well as high new production. 2. In summer, the convergence of tidal front is an important hydrodynamic process, which contributes to high biomass at frontal areas. 3. The evolution of phytoplankton blooms and thermocline in the central region demonstrate that mixing is a dominant factor to the production in the Yellow Sea. In this simulation, nitrate- and ammonium-based productions are estimated regionally and temporally. The northern Yellow Sea is one of the highly ranked regions in the Yellow Sea for the capability of fixing carbon and nitrogen. The annual averaged f-ratio of 0.37 indicates that regenerated production prevails over the Yellow Sea. The result also shows that phosphate is the major nutrient, limiting phytoplankton growth throughout the year and it can be an indicator to predict the bloom magnitude. Finally, the relative roles of external nutrient sources have been evaluated, and benthic fluxes might play a significant role in compensating 54.6% of new nitrogen for new production consumption.  相似文献   

海沧邻近海域表层沉积物中重矿物研究   总被引：3，自引：0，他引：3  

徐茂泉  沈兴兴  李超  孙美琴  许文彬 《海洋科学》2003,27(11):53-58

对厦门海沧邻近海域表层沉积物中的重矿物(0．063～0．125mm粒级)进行了分析和研究，结果表明该粒级的重矿物共计49种，其优势和特征矿物为磁铁矿、赤铁矿、褐铁矿、绿帘石、铁铁矿、角闪石、锆石、红柱石等；重矿物的平均质量分数为9．56％；根据重矿物的分布和含量，并结合主要标志矿物的颗粒百分含量和分布特征，将该海域划分为5个矿物组合区，根据各区的矿物组合类型分析了该海域的物质来源及影响重矿物分布和组合的因素，进而探讨了九龙江河口湾和厦门西港海湾的沉积环境。  相似文献   

珠江三角洲网河区水位变化趋势研究   总被引：4，自引：0，他引：4  

沈焕庭  杨清书  罗宪林  罗章仁  杨干然  欧素英 《海洋学报》2002,24(2):30-38

根据珠江三角洲网河区29个验潮站的实测验潮记录,应用傅氏变换与最平滤波器串联的方法来消除月均序列的周期波动对确定水位变化趋势的影响,由低通序列一元线性回归分析确定各站水位的变化趋势;结果表明,周期波动对确定海平面变化趋势的影响是显著的.应用经验正交函数(EOF)对网河区的水位变化场进行分解,由相互独立的时间函数和空间特征函数表征网河区区域的水位变化特征;应用时间特征函数计算区域水位的平均变化率为0.02mm/a.根据验潮站的水位变化趋势,探讨网河区水位变化与河床冲淤的关系.  相似文献   

A Computational Model for Velocity Separation in Shallow Sea   总被引：1，自引：0，他引：1  

SONG  Zhiyao 《中国海洋工程》2002,16(3):407-413

Based on the hydrodynamical feature and the theoretical velocity profiles of tidal flow and vvind-induced flow in shal-low sea, a computational model is established for the first time, which can separate observed velocity into tidal velocity and wind-induced velocity by use of the least square method. With the model, not only the surface velocities of tidal flow and vvind-induced flow are obtained, but also the bed roughness height is determined and the wind velocity above the wa-ter surface is estimated. For verification of the model, the observed velocity in the Yellow River Estuary and the laborato-ry test is separated, then it is applied to the Yangtze River Estuary. All the results are satisfactory. The research results show that the model is simple in method, feasible in process and reasonable in result. The model is a valid approach to analysis and computation of field dala, and can be applied to separate the observed velocity in shallow sea; at the same time, reasonable boundary conditions of th  相似文献   

Fractal Determination of Coastal Types Based on GIS--A Case Study of China     

Zhu xiaohua  WU Xiuqin  Wang Jian 《海洋通报(英文版)》2002,4(2)

The probability of fractal determination of coastal types based on GIS is preliminarily discussed with China as an example. Finally, some significant conclusions are drawn: (1) The fractal dimension of coastline of the bedrock coast is larger than that of the plain coast on the same scale map; (2) As far as the bedrock coast is concerned, the larger fractal dimension of coastline of the bedrock coast on the same scale map indicates that the bedrock coast is probably not typical; (3) As far as the plain coast is concerned, the smaller fractal dimension of coastline of the plain coast on the same scale map indicates that it is probably the silt plain coast; (4) The different substantial compositions affect the fractal dimensions of coastlines of different coastal types. In general, the coast which lies in the north of the Hangzhou Bay consists of sand mainly, its surface is flat, and it is connected with the coastal plain, its landform is broad shoal, its total change is comparatively homogenous in the tidal dynamic process, and thus, the relatively smaller fractal dimension of coastline results from this. For the bedrock coast, there is more bedrock, the coastline is comparatively smooth and straight, being affected by the faults and ocean dynamic process, which result in the larger fractal dimension.  相似文献   

台湾及其邻海的重力特征与构造、地震的关系   总被引：1，自引：0，他引：1  

张赤军  方剑 《台湾海峡》2001,20(1):101-109

分析认为，在台湾及其邻海的重力场中，具有短波长特征的空间重力异常受地形与海深所制约．玉山的200×10  相似文献   

Analysis of Mixing of Pollutants in Water Waves and Currents     

袁丽蓉  沈永明唐军 《中国海洋工程》2007,21(1):115-124

A vertical two-dimensional turbulence numerical model for the interaction of waves and currents is developed in the paper based on the nonlinear two-equation k-ε model with the VOF method.The one-dimensional equivalent advection velocity and equivalent mixing coefficient are defined and the solving process is introduced:The pollutant concentration field,generated by an instant source in waves and currents,is calculated with the model,and then the equivalent advection velocity and equivalent mixing coefficient are obtained by calculating the time derivative of the mean and variance of pollutant concentration probability distribution.The effects of wave period and wave height on the equivalent mixing coefficient for waves and wave-currents are also investigated.  相似文献   

长江口崇明东滩及相邻区域地形演化与驱动因素分析     

郭兴杰  严学新  王寒梅  沙伟  秦渭华  唐迎洲  徐健 《海洋学报》2020,42(5):95-103

河口大型滩涂演化关系到航运通畅、生态保护以及近岸工程的安全性，是地貌学和工程界关注的热点。利用单波束测深系统对长江口崇明东滩进行高精度监测，并结合近年来周围环境因素分析其冲淤格局。结果表明:(1) 2011?2017年间崇明东滩和北港北沙基本以淤积为主，北港北汊河槽中央局部形成?2 m心滩，?5 m等深线包络面积基本稳定，整体呈“长高不长大”的格局；(2)海洋来沙是其淤积的主要物源，汊道涨落潮时空分异而形成的两大环流是塑造此地形的主要原因；崇明东滩和北港北沙的淤积直接挤压北港北汊的发展，沙体淤积可能会引起未来两大沙体的并靠；(3)崇明东滩、北支南沿的滩涂整治工程是促进北支萎缩和崇明东滩淤积的重要因素，另外横沙通道落潮分流增加,青草沙围水工程改变了北港河槽的曲率，也有利于北港北沙的淤积。  相似文献