X波段雷达近岸影像波谱分析

X波段岸基雷达作为一种新颖的海况遥感观测方式,可直接观测到实时的海况信息。通过对雷达影像的分析,能够获得海面上的波浪场。由于波浪在近岸的折射、浅化变形等原因,观测到的雷达影像场为近岸非均匀波浪场,在一定程度上限制了传统影像分析方法——傅里叶变换的应用。针对波浪的近岸非均匀性,将二维小波变换应用于雷达影像分析,子影像中6个空间点的波数谱显示:影像中的波浪非均匀性显著,主能量的波数呈现明显的增加趋势。二维小波变换应用到X波段雷达近岸影像处理中,可较好体现近岸波浪的非均匀性。     

极端水文条件下黄茅海流场计算分析

根据黄茅海实测资料对海岸工程水动力学数学模型进行了充分验证,并采用验证后的模型对台风、大潮同时作用的"二碰头"以及台风、大潮、洪水同时作用的"三碰头"两种极端水文条件下的黄茅海流场进行计算。结果表明两种极端情况发生时,各流速特征值在崖门口处明显增加,口外"二碰头"落潮时减小,涨潮时增加,"三碰头"各流速特征值也基本都呈增加趋势,增幅相比"二碰头"较大。     

Numerical simulation of the transport and diffusion of dissolved pollutants in the Changjiang(Yangtze)River estuary

Based on a coupled hydrodynamic–ecological model for regional and shelf seas (COHERENS), a three-dimensional baroclinic model for the Changjiang (Yangtze) River estuary and the adjacent sea area was established using the sigma-coordinate in the vertical direction and spherical coordinate in the horizontal direction. In the study, changing-grid technology and the "dry-wet" method were designed to deal with the moving boundary. The minimum water depth limit condition was introduced for numerical simulation stability and to avoid producing negative depths in the shallow water areas. Using the Eulerian transport approaches included in COHERENS for the advection and dispersion of dissolved pollutants, numerical simulation of dissolved pollutant transport and diffusion in the Changjiang River estuary were carried out. The mass centre track of dissolved pollutants released from outlets in the south branch of the Changjiang River estuary water course has the characteristic of reverse current motion in the inner water course and clockwise motion offshore. In the transition area, water transport is a combination of the two types of motion. In a sewage-discharge numerical experiment, it is found that there are mainly two kinds of pollution distribution forms: one is a single nuclear structure and the other is a double nuclear (dinuclear) structure in the turbid zone of the Changjiang River estuary. The rate of expansion of the dissolved pollutant distribution decreased gradually. The results of the numerical experiment indicate that the maximum turbid zone of the Changjiang River estuary is also the zone enriched with pollutants. Backward pollutant flow occurs in the north branch of the estuary, which is similar to the backward salt water flow, and the backward flow of pollutants released upstream is more obvious.     

多层挡板桩基透空式防波堤消浪特性试验研究

本文回顾了已有的关于透空式防波堤的波浪透射率的理论计算方法,分析了多层挡板桩基透空式防波堤的消浪机理。结合防波堤断面波浪试验,探讨多层挡板桩基透空式防波堤的消浪特性。研究结果表明多层挡板桩基透空式防波堤能够显著消减波浪,它的应用突破了透空式防波堤仅适用于小尺度风浪水域的经验。研究发现影响防波堤消浪效果的因素中,挡板的透空率和设置方式的影响最为显著。文中提出的减小波浪透射率的方法可供设计部门参考。     

台湾近海水文观测体系的构建及其数据分析方法

台湾岛地处亚欧大陆和太平洋交界处,台风、东北季风等所引起的海洋灾害频繁,所以建立完备的海洋水文观测体系显得尤为重要.中国台湾自主建置完成的近海水文观测体系由资料浮标站、观测桩、潮位站、岸边气象站、雷达测波站等多种近海水文观测系统构建组成;同时,为确保观测体系的准确性和规范性,还建立了数据品质管理系统和标准化作业模式.在近海水文观测数据的分析方面,尝试应用新的数学分析方法,如通过EMD(empirical mode decomposition)方法探讨风暴潮水位变化,利用小波转换从雷达观测影像中分析近岸波浪信息,以及发展数据同化技术将观测数据应用于作业化波浪现报、预报模式.此外,近海水文观测体系在社会应用方面有着很大的发展潜质.     

徐六泾控制节点污染物运移轨迹模拟

对三维多功能动力-生态耦合模式(COHERENS)进行二次开发,运用"网格冻结法"实现了漫滩和露滩过程中的干湿交替,突破其为固定边界和限制水深的局限,使COHERENS模式成功应用于长江口浅滩过程的模拟。对潮位和水流流速的模拟结果进行了较好地验证。在斜压流场的基础上对示踪颗粒拉格朗日运移进行追踪,对污染物欧拉输运进行数值模拟。以徐六泾控制节点横断面设置颗粒示踪子和污染物排放点,对排放的悬浮颗粒物质和溶解性污染物的运动轨迹和特征进行了模拟和比较分析,给出了模拟期间的流场特征和污染物输移规律。     

由压力、流速估计波浪方向谱数据处理方法

通过现场观测水底压力和矢量流速，可以估计海面波浪方向谱，此方法称为ＰＵＶ法。本文由不规则线性波浪理论和洪广文［２］方向谱概率模式结合导出ＰＵＶ估计谱的计算式，并针对实测数据受到干扰的问题、依据相关理论与经验，提出了谱估计的数据处理与修正方法     

Analysis on the Circulation of the Yangtze River Estuary Based on ADCP Measurements

According to analysis on field data obtained by ADCP(Acoustic Doppler Current Profiler),the flow regime of the Yangtze River Estuary is studied by use of a 3-D numerical model.The flow field characteristics,under the influence of Coriolis force,saltwater intrusion and freshwater inflow and tidal current interaction,are depicted in details.The main driving forces and some important effective factors of lateral,longitudinal and horizontal circulation are also analyzed.     

南黄海辐射沙洲形成发育水动力机制研究——Ⅰ.潮流运动平面特征

基于多站潮位及潮流多日连续观测资料 ,应用二维潮流数学模型对南黄海辐射沙洲海域潮流运动进行了大、中、小潮长时间序列连续数值模拟 .并从潮流沙脊发育的动力条件出发 ,对辐射沙洲海域的潮波传播过程、潮波能流率分布、潮差平面分布、多日平均潮流流速 ,潮流椭圆及水质点迹线图进行多目标分析和研究 .数值模拟结果表明 ,潮流是形成发育南黄海辐射沙洲的主要动力因素 ,潮能率、潮流流速分布的不同决定了辐射沙洲南北沙脊、深槽的空间分布与形态