“威马逊”台风暴潮增水及水动力响应数值模拟

A numerical simulation of storm surge and hydrodynamic response caused by typhoon “Rammasun”

基于河口海岸水动力三维数值计算模型,建立浙江沿海天文潮与风暴潮耦合预报模式。利用该模式,对经过浙江沿海海域的台风"威马逊"进行数值计算,风暴潮增水计算结果与实测值符合较好,误差基本在±20 cm以内。计算增水值与传统的调和分析法所得的增水结果相比,也较为一致。进一步对局部水动力响应的研究发现,风暴潮期间,局部地区从底到表各层水流流速均急剧增大或减小,其值达到了与天文潮流同等的数量级。当水流流向与风向相同或相近时,流速增大,相反时,则流速减小。且台风期间,各层水流流向也随风向发生改变,流态变得更加复杂。

In this paper,a three-dimensional estuarine and coastal hydrodynamic model,coupled astronomical tide and storm surge,is established in coastal area of Zhejiang province.The model is validated by making a nu-merical simulation of typhoon ＂Rammasum＂ and comparing with the results by conventional harmonic analy-sis.It is shown that the modeled storm surge agrees well with the one from field observation.Further study is made on the local hydrodynamic response to the storm surge.The results show that local current velocity in each depth,with a magnitude of the same order as the astronomic tidal current,increases or decreases rapidly depend-ing on the relationship between wind and current directions.Furthermore,the current pattern gets more complicat-ed under the influence of direction-varying typhoon wind.