我国东南沿海城市和近海海域的台风极值风速预测

Extreme wind speed prediction of typhoon for southeast coastal cities and offshore areas of China

台风灾害严重影响我国东南沿海地区,通过开展台风数值模拟和极值风速预测,可精细化评估我国东南沿海城市和近海海域的台风危险性。采用基于随机森林模型的全路径台风模拟方法,对西北太平洋台风开展数值模拟,利用历史台风观测数据验证了该方法的可靠性与适用性。结合三维空间参数化台风风场模型,估算9个我国东南沿海城市不同重现期下的台风极值风速,发现广义极值分布(Ⅲ型)能更好地描述台风极值风速统计特征。将各城市的台风设计风速估算结果与GB 50009—2012《建筑结构荷载规范》中的推荐值及已有研究进行了比较,验证了台风模拟结果的可靠性,并发现低纬度城市的台风设计风速尚未超过规范中的推荐值,而高纬度城市的台风设计风速则略高于规范中的推荐值。基于台风全路径模拟和极值风速估算结果完成了我国东南沿海地区台风设计风速的区划图绘制,直观地反映了我国台湾岛及台湾东部海域的台风危险性最大,浙江东部、福建南部至广东一带以及海南岛南部等地区也面临较大的台风风险。

Typhoons severely affect the southeast coastal region of China,and it is significant to carry out typhoon simulation and its extreme wind speed prediction to refine the evaluation of typhoon hazard in the southeast coastal cities and offshore oceans of China.A full track typhoon simulation method based on the random forest typhoon models was adopted to carry out stochastic simulation of typhoons originated in the northwest Pacific Ocean,and the reliability and applicability of the typhoon simulation method were verified by historical typhoon observations.Combining with the three-dimensional spatial parameterized typhoon wind field model,the extreme typhoon wind speeds with different return periods for nine coastal cities in southeastern China were predicted.It is found that the Generalized Extreme Value(GEV-Ⅲ)distribution could better describe the characteristics of the typhoon extreme wind speed distribution.The typhoon design wind speed results are compared with the GB 50009—2012‘Load code for the design of building structures’and existing studies,which verifies the reliability of the typhoon simulation results,and it can be found that the typhoon design wind speed of low-latitude cities has not exceeded the code-recommended values,while those of high-latitude cities is slightly higher than the code value.Based on the results of typhoon full path simulation and extreme wind speed estimation,the design wind speed map in southeastern China was obtained,which visually reflects that Taiwan Island and its eastern offshore areas may suffer the greatest typhoon hazard,and the eastern part of Zhejiang Province,the region from southern Fujian Province to Guangdong Province,and the southern part of Hainan Province are also facing greater typhoon hazard risk.