南海台风风暴潮数值模拟及其对气象强迫场的敏感性试验

SENSITIVITY TESTS OF SURFACE WIND FIELDS IN TYPHOON STORM SURGE MODELING:CASES STUDY IN THE SOUTH CHINA SEA

基于FVCOM建立一个南海台风风暴潮与天文潮耦合数值预报模型。在模型的驱动场中加入模型风场与EC0.25°业务化细网格预报风场融合而成的"组合强迫场",该方法可提高对台风外围影响岸段的风暴增水及单站先兆增水的模拟精度。利用该模型对2007年9月的天文潮和0814号"黑格比"台风风暴潮过程进行模拟,选取的8个沿海验潮站的平均绝对误差为18.92 cm,平均相对误差为13.33%,对"黑格比"台风过程的最大增水时刻的模拟与实况相近,对最大增水值模拟的误差约为10 cm。分别采用模型气象场和组合气象场对1319号台风"天兔"的风暴潮过程进行模拟,两种方式对过程最大增水值和其出现时刻的模拟结果相似,但是组合气象场较好模拟出台风外围风场在福建中南部引起的增水,以及主要影响岸段潮位站在台风登陆前期的先兆增水,弥补了模型气象场在这方面的不足。

A typhoon storm surge and tide coupled numerical forecasting model covering the South China Sea was developed based on FVCOM, to＂ meet the requirement of enhancing typhoon-induced storm surge forecasting capability. A combined wind field was reconstructed by incorporating parameterized typhoon wind field with ECMWF 0.25° refined operational products, used as input to tide-surge coupled model. By combining parameterized wind field with high-resolution ECMWF operational products, the enhanced surge induced by interactions of typhoon circulation with peripheral wind field over the coasts far from the typhoon landing area, as well as the precursor surge that was well ahead of surge peak, could be reproduced. The astronomical tide during September 2007 was simulated and validated by tidal gauge data. Hagupit and Usagi storm surge were reproduced by this model and the hindcast results revealed good agreement with the observed data with regard to surge peak values and their occurrence time. The combined wind field showed its full merit of reflecting enhanced surge along the Fujian coast and precursor surge before Usagi landed on the Guangdong coast.