Estimation of significant wave period from wave spectrum

Abstract

Although the significant wave period is one of the key parameters in the design of coastal structures, it is not calculated by the spectral wave model because it is obtained by the zero-crossing analysis. The present paper examines several formulas that relate the significant wave period to wave spectral parameters such as peak period, mean period, and peakedness parameter. The formulas are derived based on the wave measurements in two locations in the Japan/East Sea (JES). The derived formulas are then compared with the measured significant wave periods in other locations in JES. It is shown that the formula using the mean wave period, Tm−1,0, is the most accurate. This formula is further used in a spectral wave model, the significant wave periods from which are compared with the measurement. Additionally, the relationship between the significant wave height and period is obtained based on the wave hindcasting, from which the most probable significant wave period can be determined for a specific significant wave height. A comparison with the measurement shows that the relationship is relatively inaccurate in the locations where southerly swell waves are significant, which are not accurately taken into account in the numerical model.