| Summary: | 碩士 === 海洋大學 === 河海工程學系 === 96 === In this research, the empirical mode decomposition (EMD) proposed by Huang et al. (1998) was introduced into the field wave statistical analyses of Gwei-San Island. The wave records were first decomposed into several intrinsic mode functions via the sifting process of ridding waves and carrier waves. After then, the zero-up-crossing method was applied at all IMFs and all individual waves were collected for the wave statistical analysis. The results were also compared to the results from traditional zero-up-crossing analysis. The comparisons show that the relations of representative waves height/period from two methods are mostly linear. The wave height from traditional zero-up-crossing analysis is larger than that from EMD wave analysis. Wave period, however, has contrary relation. From the observations on the time series of all representative wave height/period ratios, the ratios vary in different wave conditions but still show its statistical stability. Due to the EMD wave analysis can appear the long period wave characteristics in a wave train, it is helpful on the understanding of practical ocean waves.
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