海洋地质与环境重点实验室知识库

       近几十年热带气旋是对海南岛影响最大的气象灾害，随着海南深水网箱养殖规模的不断扩大，热带气旋引起的台风浪精细化预报和台风浪风险评估的需求越来越紧迫。为解决上述问题，本论文主要研究了特定网箱养殖范围内的台风浪特征、建立了海南岛近岸台风浪精细化预报系统和研究了不同海域台风浪风险对比与评估方法。
       在 本 论 文 中 ， 应 用 考 虑 了 潮 汐 和 风 暴 潮 效 应 的 风 浪 流 耦 合 模 型ADCIRC+SWAN（ Advanced circulation model， Simulating Waves Nearshore）进行热带气旋事件的后报。 2014 年“威马逊”（ RAMMASUN）台风的模拟结果和实测结果对比较好。基于 1985 年-2015 年西北太平洋历史气旋数据集，模拟了影响海南的热带气旋过程，得到了后水湾最大台风浪分布情况。这些结果用于分析波浪特征和局地风速、中心距离和气旋路径关系。统计分析的结果显示， 绕过海南岛东北部横穿琼州海峡进入北部湾这一气旋路径是对后水湾造成最大影响及破坏的路径。 最后根据设计的两组人造台风路径，寻找出对后水湾影响最大的台风路径范围。
       以海南岛周边海域为目标区域，建立了近岸养殖区台风浪数值预报系统。该系统采用非结构高分辨率网格，近岸分辨率达到了 100 m。选取 2014 年第 9 号超强台风“ 威马逊” 进行针对海南岛近岸养殖区的台风浪数值模拟后报。模拟结果与实测数据较为吻合。后采用全球预报系统 GFS（ Global Forecast System）风场和气压场数据作为驱动场对 2018 年 7 月的一次热带风暴过程进行预报， 48 小时、24小时预报的有效波高和实测结果比较平均相对误差分别为 20.75%和 17.0%。总体来说，该模型的预报精度可以满足近岸养殖区台风浪预报业务的需求。
       在本论文中，应用 ADCIRC+SWAN 模拟了最近三十年热带气旋事件。对台风飞燕（ JEBI， 2013），海燕（ HAIYAN， 2013）和海鸥（ KALMAEGI， 2014）过程模拟的有效波高和实测值进行了比较，其结果较为接近。该研究在模拟大量热带气旋事件基础上，对事件过程的最大有效波高进行统计分析，得到不同回归周期的海南岛周边海域有效波高分布。对有效波高分布图上近海二十多条设计的剖线应用仿射传播聚类算法，得到了热带气旋引起的波浪风险分类结果。分析结 果显示，海南岛近海海域任一点的台风浪风险大小是由该点所属的台风浪风险类型和水深条件共同控制的。以海南岛为例建立的台风浪风险评估方法对深水网箱产业的合理规划有着重要作用。
  

       Tropical cyclones are the most serious type of meteorological disaster that have had a great effect on Hainan Island in recent decades. With the rapid expansion of the deep sea net cage scale in the nearshore area of Hainan Island, the need for tropical cyclone-induced storm wave hazard assessment and refined storm wave forecasting are urgently needed. To solve those problems, this dissertation mainly studied the characteristics of storm wave behavior in certain deep sea net cage area, established a refined storm wave forecasting system for the coastal areas of Hainan Island and a wave hazard comparison and assessment method for different sea areas.
       In the present dissertation, the wind-wave-current coupled model ADCIRC+SWAN (Advanced circulation model, Simulating Waves Nearshore), which considers the effects of tidal and storm surges, was used to hindcast historical tropical cyclone events. Comparisons made between observations and simulated results during typhoon Rammasun (2014) indicate agreement. Storm wave were simulated in Houshui Bay on the basis of a large set of historical tropical cyclones in the North-West Pacific Basin between 1985 and 2015 to obtain the storm wave level maps. The results were used for the statistical analysis of the maximum significant wave heights in Houshui Bay associated with local wind velocity, distance from cyclone center and cyclone track. In addition, results demonstrate that the cyclone tracks passing through the northeast corner of Hainan Island into Beibu Gulf caused the most hazardous wave heights in Houshui Bay. Two groups of synthetic typhoon tracks were designed to further investigate the worst case of typhoon scenarios.
       Based on the wave-current coupled model, this study established a storm wave forecasting system for the coastal aquaculture areas of Hainan Island. This system adopted an unstructured grid with a high resolution and a nearshore resolution up to 100 m. Storm waves were hindcasted during the No.9 typhoon RAMMASUN in 2014 for the coastal aquaculture areas of Hainan Island. Results obtained were in agreement
with the measured data. Additionally, the accuracy of the storm wave forecast for a tropical storm process in July 2018 was examined by using forecasted winds at the height of 10 m above mean sea level and pressure data from the GFS (Global Forecast System). Average relative errors of 48 h and 24 h significant wave heights’ forecast were 20.75% and 17.0%, respectively. Overall, forecasting accuracy was within acceptable range and this system could satisfy the storm wave forecasting demands of the coastal aquaculture area.
       In the present dissertation, the ADCIRC+SWAN model was used to simulate tropical cyclone events in the last 30 years. Compared simulated results and observations during typhoons JEBI (2013), HAIYAN (2013) and KALMAEGI (2014) were in agreement. This study statistically analyzed maximum significant wave heights on the basis of a large set of simulated storm wave level maps to derive the wave heights of different return periods. Then, the results of nearshore wave hazard classification were obtained by applying the Affinity Propagation (AP) clustering method to dozens of nearshore profiles. The results demonstrate that the risk at any point in the nearshore area of Hainan Island is dominated by the wave hazard type and water depth condition. The wave hazard assessment method developed for Hainan Island will be significant in assisting government decision-making in the rational planning of deep sea net-cage aquaculture.