海洋中常同時存在風浪和湧浪，在頻率域上，這種交錯海象常以雙峰譜形式表現。本研究分析台灣周圍海域的雙峰波譜發現，雙峰譜出現的頻率約為8.8%，當雙峰譜出現時，平均波高為1.66m，較常年平均約低15%，顯示交錯環境下波高發展受限。同時，本研究也發現雙峰譜並非只出現在颱風期間，非颱風期間的雙峰譜出現頻率更高。為了模式化雙峰波譜，本研究利用四個前人提出的雙峰波譜模型：六參數譜(SP model)、Guedes Soares譜(GS model)、Torsethaugen譜(TT model)、Mackay譜(MK model)，套配到實測雙峰譜，結果顯示六參數譜有最佳表現。然而，分析發現模型套配過程中，當海況中湧浪能量超過風浪能量的50%以上，以及兩波峰頻率差小於0.09 Hz等條件下，前人的雙峰譜模型容易變形簡化為單峰譜，此結果並不合理，因此本研究嘗試提出新的譜模型。本文先證實了高斯分布適合來表示湧浪成分波譜，而對於風浪成分則使用JONSWAP-Glenn形式的譜模型，結合兩者成為一個新型雙峰波譜模型，本文稱之為GJ譜。透過實測數據的比對分析，根據六個評鑑參數，證實本文所提的GJ譜模型表現優於前人所提的幾個模式，與SP譜模型比較，雙峰譜變形簡化為單峰譜的比率由6%降至3%，本研究提出了一個表現更好的雙峰譜模型。

Co-exist of wind wave and swell is common in the real ocean. In frequency domain, this crossing sea is expressed by a bimodal spectrum. This study works on the bimodal analysis for Taiwanese Waters. It is found the occurrence probability of bimodal is only 8.8%. The significant wave height in bimodal sea state 1.66m is 15% lower than annual average wave height. In addition, bimodal has higher occurrence probability in non-typhoon condition. To formulate the bimodal spectra, four models presented by previous researchers are evaluated. They are Six-Parameters Spectrum Model, Guedes Soares Spectrum Model, Torsethaugen Spectrum Model and Mackay Spectrum Model. The candidate models are fitting to real bimodal spectra. The best model is the Six-Parameters Spectrum Model according to several evaluation parameters. However, it is found the bimodal spectrum deformed to uni-modal when swell energy above 50% of wind wave energy and the frequency difference less than 0.09 Hz. This is unreasonable. This study proposed a new model that is composed of a Gaussian function and a JONSWAP-Glenn model. This new model has been verified by field data and proofed to have better performance. The deformation rate reduces from 6% to 3% by using the proposed model. This study proposed a useful bimodal spectrum model for future application.

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