Research on Typhoon Swell Predict Model

• Main Authors: Yu-heng Chang, 張有恒
• Other Authors: Chao-fu Lin
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/74821716952032990140

碩士 === 逢甲大學 === 水利工程所 === 94 === In this research, we used data from six typhoons which attacked Taiwan to calculate the wave height inside the typhoon by the empirical formula which Bretschneider(1976) proposed, the formula which has been standarded in“Shore Protection Manual” (2001) and the formula which Rodolfo et al. (2002) proposed. And then we calculated swell wave height outside the typhoon by the swell computational method which was proposed by Liang Nai-Kuang(2003). The result shows that the calculated value and the actual value have obvious difference. Its reason possibly comes from the swell amassing and retrogressing effect only to consider the transfer time, but not include the rate and the direction by the typhoon forward which can influence the swell transmission. Therefore, Basing the swell wave energy through quantity per unit width at different duration between typhoon stagnating and moving should be the same, we revised the amassing and retrogressing effect coefficient, and newly calculated the swell wave heights of the six typhoons. It discover the result of predict the swell wave height by using the amassing and retrogressing effect coefficient which was suggested by this research is good. When the typhoon moves from Taiwan southeast sea area, and through Hua-Lian east sea area to Taiwan northwest sea area. But regarding the typhoon moves from Taiwan northeast sea area to Taiwan northwest sea area and from Taiwan southeast sea area to Taiwan southwest sea area, its swell wave height still had deviation in partial time. After analyzing, we estimated that the swell wave which was produced by different typhoons should has different swell attenuation constant C. After analyzing and comparing, we discovered that the typhoon belong to latter two kind tracks has a quite close relationship between the swell attenuation constant C and the ratio of the typhoon force 7 wind storm radius and the distance between the center of typhoon and the measuring station. By using regression analysis, we revised the empirical formula of calculating swell attenuation constant C of the upper two kind track typhoons. After using the new revised calculating formula and the amassing and retrogressing effect coefficient which has been considered the typhoon’s moving rate and forward diredtion to predict the typhoon swell in each kind of track, the result of predicted will be more precise.