复经验正交函数方法对湛江南三岛海滩剖面季节变化动态特征研究

利用复经验正交函数(CEOF)分析方法对湛江南三岛2009年2月22日至2010年4月21日期间的实测海滩剖面数据进行了分析。结果表明该海滩的季节变化有3个主要模态:第1模态是海滩风暴剖面和涌浪剖面之间的相互转换,其贡献占总方差的71.18%。其原因是海区侵蚀性风暴大浪和建设性涌浪的交替变化。第2模态是平均高、低潮线之间的地形变化,其原因是由于潮汐变化导致入射波浪冲流活动范围变化,占总方差的14.28%。第3模态是侵蚀大浪过后的水下沙坝向岸迁移,并受潮汐影响在滩面上摆动,占总方差的6.80%。最后指出必须重视风暴对华南海滩演变季节性过程的影响。

Using CEOF method to analyze the seasonal variation characteristics of beach profile in Nansan Island, Zhanjiang, China

A beach profile of Nansan Island,Zhanjiang,measured during February 22,2009 to April 21,2010,is analyzed with CEOF method.The results shows the beach profile variation includes 3 modes.The first complex mode,containing about 71.18% of the variance in the data,represents the interconversion of storm beach profile and swell profile induced by erosive storm wave and constructive swell wave.The second complex mode explains about 14.28% of the variance and corresponds to the beachface topography changes between mean high tide level and mean low tide level,which are mainly caused by tidal level fluctuation.The third complex mode,accounting for 6.80% of the variance,denotes the submerged bar movement onshore after erosive wave event,which vibrates on the beachface under the influence of tide.Finally,the authors point out the importance of paying much attention to the storm effect on the beach seasonal processes in South China.