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.     

钦州湾台风浪的多年一遇极值推算

利用WAVEWATCH Ⅲ(WW3)和SWAN海浪模式模拟了1949—2005年间对钦州湾海域影响较大的台风浪.以模拟结果为基础,利用皮尔逊Ⅲ(P-Ⅲ)频率适线法推算了钦州湾湾外深水的累积频率波高和平均波周期(Tm)的多年一遇极值,同时模拟了其间在百年一遇高潮水位条件下的台风浪,以及在百年一遇高潮水位、百年一遇风暴潮增水共同作用下对钦州湾影响较大的台风产生的波浪场.使用P-Ⅲ法推算了在极端天气下,钦州湾湾内统计点的累积波高和平均波周期的多年一遇极值.研究结果表明,由于湾内浅滩较多,波浪在传播过程中水体底部摩擦使能量耗损明显,所以湾内波高较小,湾口处的波高大于内湾处的波高.近岸海区的波浪耗散、破碎等物理过程比较强烈,因此近岸统计点C1处的波高极值最小,其最大波高向岸边快速减弱并沿东向传播.在极端天气情况下,波浪在传播过程中发生破碎,波高衰减显著.     

基于数值模拟的厦门湾波浪特征研究

本研究使用成熟的SWAN模型对厦门湾的波浪场进行了1a的数值模拟,通过与同期的珍珠湾波浪观测数据进行对比验证了模型的可靠性.根据模型的计算结果,分析了厦门湾年平均和夏、冬两季平均波高和波向的分布特征,厦门湾的风浪和涌浪组成,珍珠湾波浪观测海域主要的波浪能量生成和能量耗散过程.结果表明,厦门湾年平均有效波高较小,且有较明显的季节变化特征,夏季厦门湾平均有效波高较小,且湾内波向多为偏南向;冬季厦门湾平均有效波高相对较大,厦门岛北侧和东侧海域波向均为NE向.厦门湾湾内以风浪为主,涌浪较小,风浪、涌浪比较大,均在3以上;从湾外向湾内,风浪、涌浪比逐渐增加,至厦门湾南岸和泉州石井镇附近海域,风浪、涌浪比增加到5~6;在厦门湾东部和北部海域,风浪、涌浪比均在10以上.珍珠湾海域波浪最主要的能量耗散过程是由底摩擦引起的能量耗散,虽然冬季风速较大,但夏季风能输入的能量和白帽破碎耗散的能量均大于冬季;因冬季波浪相对较大,夏季底摩擦耗散的能量要小于冬季.     

SWAN模型在设计波浪要素计算中的应用研究

采用SWAN (Simulating Waves Nearshore)模型搭建了覆盖整个台湾海峡和台湾岛东部部分海域的波浪模型,并利用此模型计算了常风浪场、崇武海洋站设计波浪要素和西沙湾海域极值波浪场。计算结果显示,在常风浪模拟中,4个浮标站计算值与实测值有效波高绝对误差均在0.20 m以内,平均绝对误差值为0.13 m;崇武海洋站的设计波浪计算值与多年资料推算值平均绝对误差为0.14 m,平均相对误差为1.9%; SWAN和CGWAVE (Conjugate Gradient Wave Model)在西沙湾海域7个点的波浪极值计算值在S、SE、SSW三个方向上平均绝对误差分别为0.11、0.10、0.07 m,平均相对误差不足3%。以上计算结果表明,SWAN模型在常风浪模拟和设计波浪要素计算中具有良好的适应性。     

利用SWAN波浪模式研究北部湾海域台风浪场的波浪方向谱特征

以高精度再分析风场为驱动,利用SWAN模式模拟了台风“达维”Damrey（2005）经过北部湾海域时的波浪场。通过与实测的风和波浪实测对比发现,波浪后报结果与实测结果符合较好。文章给出了台风浪期间波高、周期、波长和波向等要素的分布特征,讨论了以台风眼为中心不同海域的波浪方向谱特征。本文最后分析了台风期间实测波浪能谱的变化特征。     

台风"泰利"过境兴化湾波浪模拟

本文利用SWAN波浪模式模拟了2005年0513号台风"泰利"影响期间兴化湾的波浪分布.模式采用计算网格为100m×100m,湾内流场、水位场由POM模式提供,风速由实测获得.模拟结果与实测资料符合良好.     

近岸较大区域波浪数值模型的比较

将适用于近岸较大区域波浪传播变形的三种模型,即基于抛物型缓坡方程的不规则波模型、引入浅水波浪谱 TMA 谱的 SWAN(simulating waves nearshore)模型以及采用默认 JONSWAP 谱的 SWAN模型应用于特拉华大学(University of Delaware)圆形浅滩实验进行比较.结果显示,抛物型缓坡方程和SWAN 的模拟结果与实验所测数据符合都比较好; SWAN 在非线性作用较强的浅滩中心及靠后部效果更佳,而抛物型缓坡方程由于没有考虑非线性作用,模拟得到的最大波高较实测值偏高,且波高变化较为剧烈.     

潮汐和潮流作用下1323号台风“菲特”台风浪数值模拟

利用第三代近岸海浪模式SWAN(Simulating WAves Nearshore)建立了基于非结构网格的台湾海峡台风浪数值模型,并以WRF模式(Weather Research and Forecasting Model)计算得到的高分辨率台风风场作为驱动,模拟了1323号台风"菲特"影响期间台湾海峡波浪场的演变过程。以实测资料进行验证的结果表明:整个模拟过程风速的平均绝对误差为1.60 m/s,有效波高的平均绝对误差为0.42 m,计算结果较好地再现了"菲特"台风影响下海峡内波浪运动过程。通过对比数值实验分析了潮汐、潮流对台湾海峡台风浪的影响,分析表明:海峡内近岸浅水区域潮汐和潮流对波浪计算的影响显著,在考虑水位和流场后,计算得到的有效波高分布曲线呈现周期性振荡,且与潮汐周期变化一致,计算得到的有效波高绝对误差下降14%,近岸波浪数值模拟的精度得到了改善。     

“烟花”台风影响下长江口水域波浪分布特征研究

台风往往会带来强风、大浪、风暴潮。强潮大浪给长江口深水航道整治工程的维护带来挑战。构建了覆盖中国海的台风浪—风暴潮耦合数学模型,模拟了台风“烟花”作用下长江口北槽水域波浪的发展过程,分析了长江口北槽水域波浪分布特点和台风强度。研究表明：叠加风场和潮汐模式共同驱动的台风浪―风暴潮耦合模型,可以准确模拟台风期间长江口水域波浪的生成和发展过程;“烟花”台风期间,外海大浪以东方向浪为主,长江口北槽南挡沙堤沿线有效波高最大值介于1.61~5.22 m之间,自东向西逐渐衰减;台风过程中,长江口北槽水域有效波高在台风二次登录时刻达到最大,口门处有5. 0 m以上大浪;依据台风过程中长江口风速及外海波高、周期与参考规范值对比分析得出,“烟花”台风过程波浪强度约为50年一遇。     

非结构网格模型在闽东沿海台风浪模拟中的应用

基于加密的非结构三角网格,以Holland模型风场叠加美国国家环境预报中心(NCEP)海面风场构造的合成风场驱动第三代浅水波浪数值模型(SWAN)对2017年影响闽东海域的"纳沙"和"泰利"台风过程进行数值模拟,并运用浮标站的实测数据对模拟结果进行验证.结果表明,模型计算的风速、有效波高与实测值符合较好,合成风场能较好地模拟台风期间的风速变化过程,SWAN模式能够合理地再现闽东沿海台风浪的时空分布特征.由模拟结果可见:台风"纳沙"中心越过台湾岛进入台湾海峡北部海面,受海峡地形的约束,其波浪场呈NE—SW向椭圆状分布,北部海域的浪高大于南部,闽东沿海遍布大范围的巨浪到狂浪;超强台风"泰利"未登陆闽东,当其台风中心与大陆的距离最近时,海面波浪场分布与台风风场结构一致,台风中心附近海域为14 m以上的怒涛区,巨浪遍布于闽东沿海.研究结果可为闽东沿海台风浪灾害预警和应急管理提供技术支撑和参考依据.     

Limitations of the streamtube model

A common feature of one-dimensional streamtube models is that the pressure gradient includes only the effect of the density difference between the plume and the ambient water on a sloping bottom. Variations of the streamtube height and density along the flow path are thus neglected. In the present paper a streamtube model is used to highlight the assumptions underlying the simplification and to obtain the limitations this prerequisite presents. The results indicate that the parameter range for which the simplification is applicable is largest when the initial outflow is parallel to the isobaths. More specific limits are given for three major outflows — the Mediterranean, the Faroe Bank Channel and the Denmark Strait outflow.     

Management of the coastal-sea-zone-ecosystem model

We present a model of the processes of development in the ecosystem of the coastal zone of the sea constructed by the method of adaptive balance of causes (ABC-method). The model contains nine variables (phyto- and zooplankton, fish larvae, fishes, oxygen, carbon dioxide, salinity, biogenic elements, and detritus) affected by the solar radiation, surface wind, sea temperature, and river discharge. The equations of the model contain control agents governing the dependences of the elements of the food chain on the vitally important resources and environmental conditions. The scenarios of the processes of development are constructed for the simulated annual courses of external actions. The possibility of management of fish resources by regulating the flows of biogenic elements and detritus with river discharge is discussed. A mechanism of management based on the monitoring of the concentration of dissolved oxygen in seawater is proposed. The numerical experiments show that the ABC-model of the processes of development in the ecosystem of the coastal zone of the sea makes it possible to simulate the scenarios of regulation of the flows of biogenic elements and detritus into the sea with an aim of preservation of of fish resources. Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp. 36–49, January–February, 2009.     

土壤-地雷共振系统模型解析

在研究土壤-地雷共振系统模型的基础上,提出一种共振与反共振相结合的声波探雷模型.根据地雷顺性大及低频声学的特征,把地雷与其上方的土壤分别等效为弹簧和质量块,构成质量-弹簧共振系统,通过对系统频响函数的解析,讨论模型的共振与反共振现象.通过实验发现有、无地雷的地表振动速度比值存在大于1的极大值频率点和小于1的极小值频率点交替出现的现象,与理论预测符合.表明土壤-地雷共振系统同时存在共振与反共振现象,可用于地雷成像的研究.     

The synchronous coupling of a third-generation wave model and a two-dimensional storm surge model

The interaction of waves and currents is studied by the dynamical coupling of a third generation wave model and a two-dimensional storm surge model. The coupling process of the two models is implemented synchronously. To estimate the effects of waves on the generation of storm surges, the theory of Janssen is used. The effects of the wave radiation stress on surge levels and the effects of storm-induced currents on waves are also investigated.The coupled wave and storm surge models have been tested by hindcasting two storm events in the northern South China Sea. The use of the Simth and Banke stress relation underestimates the surges by 10%. The inclusion of the radiation stress improves the accuracy of the computed results slightly by 2%. The introduction of a wave-dependent surface drag gives a significant improvement. The storm-induced currents clearly affect the wave characteristics at the peak stage. However, as far as the prediction of wave height is concerned, it is better not to consider the wave radiation stress in the storm surge model unless this is accompanied by a wave-dependent surface drag.     

LAGFD-WAM numerical wave model——Ⅰ. Basic physical model

The LAGFD-WAM wave model is a third generation wave model. In the present paper the physical aspect of the model was shown in great detail including energy spectrum balance equation, complicated characteristics equations and source functions.     

Performance of a numerical short-wave model

A numerical short-wave model system based on the Boussinesq equations is verified against analytical as well as experimental results for shoaling, refraction, diffraction and partial reflection processes. It is shown that engineers can confidently and responsibly apply such a model system to the study of wave disturbance in coastal regions.     

Calibration of a two-dimensional hydrodynamics model

This paper reports the approach and results of calibrating a two-dimensional hydrodynamics model. The model was applied to Humboldt Bay, California, and calibrated with synoptic tidal data at four locations. The model calibration was done by using both a trial-and-error approach and a parameter identification (PI) method. For the given finite-difference grid resolution and field observations, the calibration attempt revealed that the two methods produced two different sets of parameters, but with almost identical comparisons between the model solutions and observations. The study results indicate that the appropriate range of model parameter values can be more efficiently identified by parameter identification method, and the best calibration strategy is to use both methods conjunctively.     

复合模型系统的控制策略

复合模型中的物理模型和数学模型是依靠计算机控制系统实时耦合起来的。复合模型对控制系统的精度要求较高 ,但是流量的控制中存在着水流的滞后性以及水位控制中的超调现象 ,这些问题都将影响控制的精度。本文介绍采用改进的PID与Smith控制算法相结合的控制策略实现流量控制 ,以解决水流的滞后性 ;采用变参数PID控制策略实现水位控制。试验证明两者都取得了较好的控制效果     

Three-dimensional hydrodynamic model of Xiamen waters

Abstract-A semi-implicit and Eulerian-Lagrangian finite difference method for three-dimensionalshallow flow has been extended to a more complete system of equations incorporating second-momentturbulence closure model and transport equations of salinity and temperature. The simulation for flood-ing and drying of mudflats has been improved. The model is applied to Xiamen waters. Based on exten-sive survey data, water level elevation, temperature and salinity field along the eastern open boundaryand at the Jiulong River inlets and runoffs are analyzed, specified and calibrated. The computed resultsshow good agreement with the measured data, reproduce flooding, emergence of large and complexmudflat region.     

Combined chemistry-climate model of the atmosphere

A combined three-dimensional global model of the chemistry and dynamics of the lower and middle atmosphere (up to 90 km from the Earth’s surface) is described. With the use of this model within the AMIP2 (1979–1995) program, numerical calculations were performed with consideration for the interactive coupling between the ozone content, radiation heating, and atmospheric circulation. Comparisons were made between calculated and observed data on the ozone content and temperature. Heterogeneous processes on the surface of polar stratospheric clouds were shown to be important for a correct simulation of the spatial and temporal distribution of atmospheric ozone.