响水海域畸形波特性初探

摘要

Based on the definition of freak wave in shallow water“The wave height exceeding twice the signifi⁃cant wave height, which is larger than 1.0 m”, coastal freak waves were selected in a three⁃year wave data series in Xiangshui, Jiangsu. Fast Fourier Transform and Wavelet Transform were applied to the wave records respectively. FFT results show typical bimodal characteristics, and WT results show the freak waves can be grouped into two cate⁃gories. Energy of the low⁃frequency component increases significantly in both groups while that of the high⁃frequen⁃cy component is sometimes of the same order and sometimes negligible. A comparison was made between the wave⁃let spectrum of freak waves and that of a typical kind of freak wave mentioned in previous literature. By calculating the Irribaren coefficient, it is further convinced that the infragravity wave in this area contributes to the low⁃frequen⁃cy component. Preliminary statistical analysis of the wave direction and the seasonal distribution is given.%基于“单波波高大于两倍有效波高且有效波高大于1m”的浅水畸形波定义，从江苏响水站连续3a的波记录中挑选出畸形波数据，对其进行谱分析和小波分析。谱分析显示该海域波浪呈现典型的双峰特性。小波分析的结果可分成两类，均显示畸形波出现时刻低频成分的能量显著增高，而高频成分的能量在第一类中相对较低，在第二类中很小可忽略。将该小波谱和前人文献中描述的一种典型畸形波的小波谱进行了对比，并通过计算Irribaren系数证实了该海域长重力波存在的可能性，为低频成分的来源提供了依据。并通过波向和发生季节对畸形波所在波记录进行了初步的统计分析。