台湾海峡及厦门湾台风浪场数值模拟

本文利用国际上先进的第三代海浪模式SWAN,在充分考虑风能量输入、白浪效应、水深诱导的波浪破碎、底摩擦、波-波间的非线性相互作用等物理过程。以0604号台风"碧利斯"为例,通过嵌套计算方式,模拟了台湾海峡及厦门湾台风浪场的分布特征。将数值模拟结果与浮标测站实测资料对比分析,结果表明台风浪高模拟值与实际台风资料相符较好,可以为该海域台风浪的模拟提供较好的参考。     

0908号台风“莫拉克”影响期间福建西沙湾海域台风浪的数值模拟

联合SWAN模型和改进的椭圆型缓坡方程,结合考虑台湾海峡地形效应的改进藤田公式风场模型,建立了台湾海峡及近岸波浪场的数值嵌套模式.边界采用波谱离散驱动,模拟了0908号台风“莫拉克”期间台湾海峡波浪场的演变和崇武西沙湾浅水台风浪传播的物理过程.以实测数据进行单点验证表明,整个模拟过程风速的平均绝对误差为3.38 m/s,波高的平均绝对误差为0.30 m,计算结果较好地反映海峡内波浪对台风的响应过程.“莫拉克”台风登陆台湾岛时,台湾海峡有效波高最大值为5.0m;台风中心进入台湾海峡后,海峡东北部为巨浪到狂涛,有效波高最大值可达10.5 m.接近福建崇武沿岸时,偏E向台风浪向西沙湾内近岸传播,发生浅化、破碎、反射、绕射等变形现象,有效波高最大不足2 m,最小仅为0.2m,波向趋于SE向,波峰线则趋于与峡湾岸线平行;崇武闽台贸易码头附近,大部分波浪受到阻挡作用发生反射,少部分发生绕射,使得码头以北水域波浪较小,有效波高仅为0.2 ～0.6 m,对湾内避风坞起到较好的保护作用.     

南海北部一次台风浪过程的数值模拟

采用Holland 模型将2009 年6 号台风莫拉菲参数化, 并通过一个权重系数将模型风场和背景风场叠加起来, 构造了南海北部台风过境时的风场。随后通过时空插值, 将该风场以空间分辨率5′×5′、时间步长1 h 的精度输入到SWAN(Simulating Waves Nearshore)模式中, 模拟了莫拉菲台风通过时南海北部的海浪场。然后使用Jason-2 卫星波高数据对模式进行了验证, 结果表明模式结果与实测值吻合良好。利用模式结果我们分析了台风中心和海浪场的最大有效波高中心的位置关系, 以及台风风场结构和海浪场结构的关系。最后, 通过计算海浪场的能量并将其与风要素和浪要素对比, 我们研究了台风过境期间海浪场的动力机制。     

A study of dissipation of wind-waves by mud at Cassino Beach,Brazil: Prediction and inversion

The impact of a non-rigid seafloor on the wave climate at Cassino Beach, Brazil, May–June 2005 is studied using field measurements and a numerical wave model. The measurements consist of wave data at four locations; rheology and mud thickness from grab samples; and an estimate of the horizontal distribution of mud based on echo-soundings. The dissipation of waves by a non-rigid bottom is represented in the wave model by treating the mud layer as a viscous fluid. Applied for 431 time periods, the model without this type of dissipation has a strong tendency to overpredict nearshore wave energy, except during a period of large storm waves. Two model variations which include this dissipation have a modest tendency to underpredict the nearshore wave energy. An inversion methodology is developed and applied to infer an alternate mud distribution which, when used with the wave model, yields the observed waveheights.     

SWAN模式对黄渤海海域浪高的模拟能力试验

SWAN模式即第三代浅水波浪数值预报模式,不仅能仔细考虑能量平衡方程式中的各项源函数,而且对近海海域(浅水)以及复杂地形海域的浪高有很好的模拟能力。本文在简述我们从青岛海洋大学“九.五”国家重点科技攻关项目中引进的SWAN模式的基础上,详细论述了T213和MM5两种风场资料在SWAN模式中的应用及对比验证。发现MM5海平面上空10m处风场资料优于T213的1000hPa风场资料,用在SWAN模式对黄渤海海域浪高模拟中预报结果较好。     

太湖不同湖区风浪的季节变化特征

为明晰太湖风浪的空间分布及季节变化,在湖心区设立波浪观测站,利用其记录的波浪数据证明SWAN模型能够较好地模拟太湖风浪.基于所建模型,对2013年自然风场条件下太湖不同湖区风浪季节动态进行模拟分析,结果表明:受岸线、地形和岛屿等地理因素影响,大太湖的风浪总是最强,其有效波高均值为0.523 m;而东太湖风浪最小,有效波高均值为0.305 m.受盛行风场季节变化影响,太湖春、夏季有效波高均值明显大于秋、冬季.太湖波浪的能量主要来源于风场,其有效波高随风速增大而增大,两者呈极显著正相关.而风向则可以通过改变风区长度来影响风浪生消.在偏东风作用下,太湖湖西区的风浪大于东部湖区;而受盛行于冬季的偏北风影响,太湖南部水域风浪要大于北部.同时,太湖风浪的时空分布特征是造成太湖水质参数、沉积物和水生植物空间分布差异的重要原因之一.     

长兴岛海区波流相互作用数值模拟研究

波和流是近岸海区的主要动力因素。应用二维潮流数学模型和最新第三代近岸海浪模式SWAN,建立了非结构网格下二维情况近岸波流耦合作用数学模型。时间离散采用欧拉向前格式,空间离散采用有限体积法显式格式。通过将波浪场及潮流场进行迭代耦合计算,实现了对波流共同作用下波浪场和潮流场的数值模拟。将模型应用于矩形海湾实验和李孟国数模实验等理想地形以及大连长兴岛海区实际复杂地形算例,并用现场实测资料对计算结果进行验证,结果表明:耦合结果与实测结果吻合良好,并且要优于未耦合的结果。     

基于Boussinesq方程近岸波浪演变的数值研究

首先对目前描述近岸波浪传播变形的数学模型进行了回顾与总结;对不同数学模型的特点、适用范围和发展情况进行了阐述与对比。应用基于Boussinesq方程的Coulwave模式针对几个经典实验地形进行了数值实验,数值结果和实验实测数据吻合较好。此外,分别采用不同的近岸波浪模型模拟了某渔港附近波浪的传播变形,结果表明:当考虑波浪的折射、绕射、反射联合作用时,Coulwave模式计算结果明显较缓坡方程及SWAN模型计算结果更加合理。     

A ten-year data set for fetch- and depth-limited wave growth

This paper presents the key results from a ten-year data set for Lake IJssel and Lake Sloten in The Netherlands, containing information on wind, storm surges and waves, supplemented with SWAN 40.51 wave model results. The wind speeds U₁₀, effective fetches x and water depths d for the data set ranged from 0–24 m s^− 1, 0.8–25 km and 1.2–6 m respectively. For locations with non-sloping bottoms, the range in non-dimensional fetch x? ( = gxU₁₀^− 2) was about 25–80,000, while the range in dimensionless depth d? ( = g d U₁₀^− 2) was about 0.03–1.7. Land–water wind speed differences were much smaller than the roughness differences would suggest. Part of this seems due to thermal stability effects, which even play a role during near-gale force winds. For storm surges, a spectral response analysis showed that Lake IJssel has several resonant peaks at time scales of order 1 h. As for the waves, wave steepnesses and dimensionless wave heights H? ( = gH_m0U₁₀^− 2) agreed reasonably well with parametric growth curves, although there is no single curve to which the present data fit best for all cases. For strongly depth-limited waves, the extreme values of d? (0.03) and H_m0 / d (0.44) at the 1.7 m deep Lake Sloten were very close to the extremes found in Lake George, Australia. For the 5 m deep Lake IJssel, values of H_m0 / d were higher than the depth-limited asymptotes of parametric wave growth curves. The wave model test cases of this study demonstrated that SWAN underestimates H_m0 for depth-limited waves and that spectral details (enhanced peak, secondary humps) were not well reproduced from H_m0 / d = 0.2–0.3 on. SWAN also underestimated the quick wave response (within 0.3–1 h) to sudden wind increases. For the remaining cases, the new [Van der Westhuysen, A.J., Zijlema, M., and Battjes, J.A., 2007. Nonlinear saturation-based whitecapping dissipation in SWAN for deep and shallow water, Coast. Eng., 54, 151–170] SWAN physics yielded better results than the standard physics of Komen, G.J., Hasselmann, S., Hasselmann, K., 1984. On the existence of a fully developed wind-sea spectrum. J. Phys. Oceanogr. 14, 1271–1285, except for persistent overestimations that were found for short fetches. The present data set contains many interesting cases for detailed model validation and for further studies into the evolution of wind waves in shallow lakes.     

浅水波浪数值模型SWAN的原理及应用综述

概述了模拟海岸、河口的浅水波浪数值模型研究现状、存在的问题以及用能量平衡方程预报海浪的发展历史。介绍了基于当代最新波浪理论研究成果的第三代浅水波浪数值模型SWAN模型,对模型的适用性、数值特性、功能及局限性进行了阐述。介绍动谱平衡方程数学模型、方程离散要求、边界条件的处理和源项(包括能量输入、损耗及波与波之间非线性相互作用)的处理方法,重点介绍三相波非线性相互作用。模拟海安湾有效波高、波周期场,并分析波与波之间非线性相互作用对波浪要素预报的影响,最后对SWAN模型的应用前景和研究趋势进行了展望。