基于无结构网格有限体积法的风暴潮数值预报模式

基于无结构三角单元网格和有限体积法,建立了一个高精度高分辨率的风暴潮二维数值预报模式。该模式采用对岸线有较强拟合能力的无结构网格对求解区域进行离散,采用藤田公式和宫崎正卫风场模式模拟气压场和风场。由于台风暴潮在近岸地区受底部地形的影响,可能引起非线性较强的波动,从而产生陡度大的波面,因此模式中利用Roe的通量函数给出守恒方程的无粘性通量。针对复杂的海底地形,对模式专门进行了通量梯度项与源项的平衡。应用此模型模拟和预报珠江口地区的风暴潮增水,取得了较满意的结果。     

A BFG model for calculation of tidal current and diffusion of pollutants in nearshore areas

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A1B气候情景下海平面变化对东中国海风暴潮的影响

用三维水动力模型Ecomsed,在第四次IPCC评估报告SRES A1B气候情景下,分析21世纪海平面变化对东中国海风暴潮及沿岸脆弱性的影响。在A1B气候情景海平面变化影响下,对17个台风个例进行模拟。结果表明:受海平面变化影响风暴潮增减水出现大概10 cm的变化,风暴潮增水提前,风暴潮增水时段延长;台风强度越大,海平面变化对风暴潮增水强度的影响越明显。海平面变化对海岸带脆弱性具有很大影响,苏北浅滩及环渤海海岸带脆弱性将增强,校核水位在东中国海将会增大。     

近岸海浪、风暴潮及海啸灾害远程实时监测系统的现场试验及应用

利用自主研发的近岸海浪、风暴潮及海啸灾害远程实时监测系统,在广东省阳江市闸坡附近海域进行了远程实时监测试验.文章介绍了监测系统的组成,对2007年9月1日-10月3日的观测记录进行了分析,计算出台风增水、波高和波周期,采用低通滤波方法获得重力外波.实验结果表明,研发的近岸海浪、风暴潮及海啸灾害远程实时监测系统可供实际推广应用.     

A typhoon-induced storm surge numerical model with GPU acceleration based on an unstructured spherical centroidal Voronoi tessellation grid

Storm surge is often the marine disaster that poses the greatest threat to life and property in coastal areas.Accurate and timely issuance of storm surge warnings to take appropriate countermeasures is an important means to reduce storm surge-related losses.Storm surge numerical models are important for storm surge forecasting.To further improve the performance of the storm surge forecast models,we developed a numerical storm surge forecast model based on an unstructured spherical centroidal Voronoi tessellation(SCVT)grid.The model is based on shallow water equations in vector-invariant form,and is discretized by Arakawa C grid.The SCVT grid can not only better describe the coastline information but also avoid rigid transitions,and it has a better global consistency by generating high-resolution grids in the key areas through transition refinement.In addition,the simulation speed of the model is accelerated by using the openACC-based GPU acceleration technology to meet the timeliness requirements of operational ensemble forecast.It only takes 37 s to simulate a day in the coastal waters of China.The newly developed storm surge model was applied to simulate typhoon-induced storm surges in the coastal waters of China.The hindcast experiments on the selected representative typhoon-induced storm surge processes indicate that the model can reasonably simulate the distribution characteristics of storm surges.The simulated maximum storm surges and their occurrence times are consistent with the observed data at the representative tide gauge stations,and the mean absolute errors are 3.5 cm and 0.6 h respectively,showing high accuracy and application prospects.     

浙江沿海超强台风风暴潮灾害的影响及其对策

对浙江省历史台风基本资料进行分析后发现,近年来台风严重影响浙江的趋势和登陆浙江的台风个数均有明显的增强和增加.浙江省沿海各测站的历史最高潮位均由台风暴潮引起,其中"9417"号、"9711"号两次台风与天文大潮遭遇引起的风暴潮次数占了绝大多数.受台风暴潮影响时,岸边观测到的潮位由天文潮和台风引起的增水两部分组成.采用潮波与风暴增水耦合的非线性效应模型研究了风暴潮.在验证"5612"号、"9417"号、"9711"号、"0414"号、"0509"号和"桑美"6场台风暴潮的基础上,模型以1949年以来我国大陆沿海最强的一次台风("5612"号台风)参数为基础,设计了台风在浙北(穿山)、浙中北(石浦)、浙中(椒江)、浙中南(坎门)和浙南(琵琶门)登陆的5条路径,以反映超强台风在浙江沿海不同地点登陆与天文高潮位"碰头"时可能造成的最高潮位,它可以基本代表超强台风登陆浙江沿海时的风暴潮位.根据两潮耦合模型计算得到的沿海高潮位与海塘塘顶高程进行比较,分析沿海海塘发生漫顶甚至溃堤的可能性.通过对海塘可能损毁机理的分析,根据不同登陆线路的超强台风在遭遇天文大潮高潮位时对浙江沿海可能造成的威胁程度进行淹没风险分析.在上述计算分析的基础上,结合浙江沿海的实际情况,提出相应的防御超强台风风暴潮的工程和非工程措施.     

风暴潮、大潮对广西涠洲岛西南沙滩侵蚀的影响分析

本文统计分析了广西涠洲岛沿海气候、潮汐和风暴潮等历史资料,利用耿贝尔方法推算了涠洲岛多年一遇年极值高潮位,并估算了其漫滩范围分布,指出近几年高潮位出现的频次和极值均越来越高是涠洲岛西南部沙滩侵蚀愈加严重的重要原因,最后结合风暴潮-海浪耦合数值模拟了研究区域内"0312"号台风风暴潮漫滩的情况,分析了风暴潮和大潮对涠洲岛西南部沙滩侵蚀的影响,对当地岸滩修复和防护具有一定的指导意义。     

2018年秦皇岛风暴潮前后岸基站及浮标主要水质参数变化分析

对2018年8月秦皇岛风暴潮期间3个入海口岸基站及邻近海域浮标的监测数据进行分析,结果显示:风暴潮导致入海口水体中COD、总磷、总氮和氨氮含量均明显升高;风暴潮2 d之后,3个入海口邻近海域均发生赤潮,此次赤潮的发生与风暴潮导致陆源入海污染物骤然大幅升高有关。此次风暴潮导致秦皇岛人造河口、大蒲河口和七里海3个岸基监测站的COD监测日均值最高分别达到15.83 mg/L、8.70 mg/L和7.92 mg/L,约升高至前期的2倍、1.5倍和2倍;人造河口总氮变化不大,大蒲河口和七里海总氮升高30%左右;大蒲河口总磷变化不大,人造河口总磷为前期的3.5倍,升高幅度最大,七里海总磷为风暴潮之前两日的2倍,但未超过前一周的最高浓度;风暴潮当天及第二天,人造河口、大蒲河口、七里海氨氮日均值陆续达到最高,分别为2.34 mg/L、1.11 mg/L和0.12 mg/L,分别为风暴潮前两日的7倍、3.5倍和10倍。风暴潮过后,入海口临近海域发生赤潮,浮标监测到叶绿素a最高值为76.4μg/L,pH和溶解氧也大幅升高。分析表明,此次风暴潮导致的入海口污染物突然大幅升高为风暴潮之后的赤潮发生提供了充足的营养基础。     

江苏中部海岸全新世中期温暖期风暴潮频率的研究

通过对采集于江苏省盐城市上冈镇的三个柱状沉积剖面(W,M,E)的岩性特征及其对比关系的分析、沉积物14C年代的测定以及沉积物样品的粒度、磁化率特征的分析,结合有孔虫和颗石藻的分析结果,判定研究沉积层段为全新世中期的潮滩沉积.孢粉分析结果显示当时的气候较现在温暖.以潮汐层理的周期性特征为依据,对以泥为主的潮滩沉积剖面中每隔10~20cm有规律出现的一层砂作了分析,结果表明这一沉积特征为季节性的潮滩沉积旋回.在此基础上,观察沉积剖面中的风暴潮事件的记录状况,估算出剖面中记录的与9711号台风风暴潮强度相当的风暴潮的发生频率为二至四年一遇,而依据盐城市东台梁垛河闸多年的现代最高潮位资料,应用耿贝尔(Gum-bel)曲线拟合法计算出的9711号台风所引起的风暴潮频率为十二年一遇,即全新世中期温暖期的台风风暴潮的频率比现在大.据此推测全球变暖后台风风暴潮的频率将会增加.     

A numerical model of wave overtopping on seadikes

This paper describes the development of a numerical model for wave overtopping on seadikes. The model is based on the flux-conservative form of the nonlinear shallow water equations (NLSW) solved with a high order total variation diminishing (TVD), Roe-type scheme. The goal is to reliably predict the hydrodynamics of wave overtopping on the dike crest and along the inner slope, necessary for the breach modelling of seadikes. Besides the mean overtopping rate, the capability of simulating individual overtopping events is also required. It is shown theoretically that the effect of wave breaking through the drastic motion of surface rollers in the surfzone is not sufficiently described by the conventional nonlinear shallow water equations, neglecting wave setup from the mean water level and thus markedly reducing the model predictive capacity for wave overtopping. This is significantly improved by including an additional source term associated with the roller energy dissipation in the depth-averaged momentum equation. The developed model has been validated against four existing laboratory datasets of wave overtopping on dikes. The first two sets are to validate the roller term performance in improving the model prediction of wave overtopping of breaking waves. The last two sets are to test the model performance under more complex but realistic hydraulic and slope geometric conditions. The results confirm the merit of the supplemented roller term and also demonstrate that the model is robust and reliable for the prediction of wave overtopping on seadikes.