颱風為每年影響台灣最嚴重之天氣型態，平均每年約有3~4個颱風侵襲台灣，期間所產生之颱風波浪不僅對海岸工程、海事結構物造成傷害也嚴重威脅濱海居民之生命財產安全。因此，研究長期颱風波候變遷的趨勢可作為日後海岸保護、政策決策及工程設計時之參考。
由於有限的觀測資料使然，透過輸入風場於波浪模式進而模擬長期颱風波浪成為一可行之方法，本研究利用德國HZG研究中心所提供之高解析風場輸入SWAN波浪模式，能較合理地描述颱風於時間及空間上變化快速之特性。本研究初步對過去十年間之第二路徑颱風所造成之颱風波浪( )做率定與驗證。
本研究首先透過敏感度分析決定模式率定之參數，結果顯示 為主要影響模式輸出結果之參數，底床摩擦係數以及碎波消散係數並沒有顯著的影響。本研究進一步利用可適隨機搜尋法配合OBJ函數搜尋 之最佳參數值，使模式結果盡可能與實測資料一致。以碧利斯和蔷密颱風驗證最佳參數值之適用性並與龍洞、蘇澳與花蓮浮標所測得之波浪資訊做比較，結果顯示模式率定後之模擬結果明顯改善示性波高之模擬，但在平均週期的模擬上則略差於率定之前。
由於波浪可由許多不同頻率的組成波疊加組合而成，海浪的總能量由更組成波提供。透過對波譜的分析可了解波浪能量相對於組成波頻率的分佈。因此本研究進一步討論率定前後是否改善模式在波譜上的模擬結果，在定性以及定量的分析上顯示模式率定後在波譜的模擬上與實測更為貼近。

Typhoons play a major role in engineering and environmental problems. Statistical number from Central Weather Bureau (CWB) of Taiwan shows that there are in average 3.5 typhoons approaching Taiwan per year. It is often subject to severe sea states induced by typhoon waves, resulting in terrible losses of human life and property in the coastal area of Taiwan. Therefore, analysis of typhoon waves and long-term changes of typhoon wave climate are of great importance to the operation and safety of shipping, offshore industries, and coastal development.
Our long-term goal is to investigate variability and trends of typhoon waves over past 60 years. Unfortunately, the long observational records are hardly available. Therefore, hindcasts by the wave models become a common tool to complement the limited observational record.
In this study, we used HZG high-resolution wind field to drive the SWAN wave model. Before the model can be applied to the specific region, we have to calibrate the parameters of the wave model. First of all, we selected the 3 most important parameters from the source term of the SWAN wave model and subjected them to sensitivity analysis to determine which parameter is the most sensitive. The result showed that is the most sensitive parameter. After sensitivity, we adopted adaptive random search (ARS) to find the optimal value of the for improving the simulation of typhoon waves ( ). The accuracy of simulations of significant wave height using calibrated value of in the SWAN wave model was greatly improved over reference simulations at the Longdong, Suao and Hualien buoy station. However, the accuracy of mean period was slightly underestimated over reference simulations.
Even though significant wave heights and mean periods are common parameters to evaluate spectral wave models, the SWAN wave model predicts the full wave spectrum; therefore, a simplified validation based on integrated parameters can be misleading. This study provides an analysis of predicted wave spectra for the two verification typhoons. The results showed that the accuracy of wave energy was also improved greatly over reference simulations.

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