不规则区域海浪嵌套模式设计及其应用实例

摘要

A new nested wave model is designed based on the parallelized MASNUM (key laboratory of marine science and numerical modeling) wave model developed by First Institute of Oceanography of Static Oceanic Adminis-trate,China.The flexibility and efficiency of this nested model are improved using parallel computation and irregular open boundary.This nested wave model is applied to the region of Zhoushan and Ningbo in Zhejiang Province through a triply nesting in order to simulate the wave using the NCEP reanalyzed wind fields in 2011 as the forcing.The experiments in big and mid region are designed through regular rectangle open boundary,the simulation results of the experiment in big region provide the corresponding open boundary conditions for nesting experiment in mid region,the simulation results of the experiment in mid region and irregular open boundary conditions for the nesting experiment in small region.The comparison of experiments in middle region with the satellite observations indicate that the error of significant wave height is reduced about 30％ because of the nesting and the difference due to nesting is bigger near the open boundary which reaches more than 0.5 m.The simulated averaged and maximum wave height are 0.7 m and 3.6 m in summer time from the experiment without nesting in middle region,while they are 1.0 m and 7.1 m from nesting one which is much closer to the results of 1.5 ～2.0 m and 5.0 ～ 10.0 m from historical records.The results show that the nested model is feasible to regular nesting of wave model with the rectangle open boundary.For the small region,there are also 2 experiments,one without nesting and the other with nesting.The open boundaries for them are designed as an irregular shape.As the result,the simulated wave direction from the nested wave model in smallest region shows that the waves are mainly propagated from the outer seas during May to August,2011 and it is quite different with those results in the one without nesting.The difference of the significant wave height is greater than 1.0 m during June to July,and the simulated wave periods from nesting experiment are generally larger than the one without nesting and the maximum reaches to 8 s.In a conclusion,this nested wave model which is workable for the open boundary with a regular rectangle or an irregular shape.It also indicated that this model can be applied for the wave simulation or predictions in realistic and complicated coastal regions with improved performance.%本研究针对第三代MASNUM海浪模式的并行设计特点,设计实现了并行化不规则嵌套计算,从而提高了海浪模式嵌套模拟的灵活性和时效性.选取浙江舟山、宁波附近海域,利用201 1年的NCEP再分析风场作为强迫,采用大、中、小网格并利用该嵌套模式进行了三重嵌套应用.其中大、中区域实验均采用规则矩形方式设置开边界,大区域的模拟结果为中区域嵌套实验提供开边界条件,同时中区域嵌套输出小区域嵌套实验在不规则开边界上的边界条件.中区域的实验结果与卫星观测资料的对比表明:嵌套实验比无嵌套实验的误差小30％左右,二者在开边界附近的有效波高差异较大,达到0.5m以上.8月份中区域的无嵌套实验所得有效波高平均为0.7m,最大值为3.6m,嵌套实验结果则分别为1.0、7.1m,后者更接近以往观测资料所显示的平均波高1.5～2.0 m和最大波高5.0 ～10.0 m的结果,表明该常规嵌套方式的可行性.小区域实验也包含嵌套和无嵌套2个实验,开边界均采用不规则形状.实验结果表明:在5～8月期间,嵌套实验的波向与无嵌套的波向差异较明显,主要表现为外海传入；在6～7月份,嵌套实验与无嵌套实验有效波高的差值达1.0m以上；嵌套实验的周期普遍大于无嵌套的模拟结果,其最大差异为8 s.上述实验结果表明,该嵌套模式可实现规则开边界区域和不规则区域的嵌套模拟,可应用于复杂近岸区域的海浪数值模拟和预报,有效提高对关注区域海浪的模拟能力.