1991-2011年东海黑潮PN断面流结构与季节变化分析

Analysis of current structure and seasonal variation at PN Section of the East China Sea Kuroshio during 1991-2011

基于日本海洋信息中心提供的东海黑潮PN断面CTD资料,本文采用动力高度法计算了1991-2011年间90个航次的断面流速,并对流场结构、最大流速、流幅和流量进行了统计分析。结果表明:东海黑潮PN断面流场存在单核、双核、多核3种结构;其中单核结构出现的概率为50%,双核结构为39%,多核结构为11%。东海黑潮的流结构存在显著的季节变化:秋季多核结构所占的比重为4个季节最大,平均流核数最多;冬季主要为单核结构,平均流核数最少;夏季和春季则没有明显的倾向性,单核、双核、多核3种结构出现概率相近,平均流核数介于秋季和冬季之间。其次东海黑潮的流量也存在显著的季节变化:冬季与夏季最强,秋季最小,春季居中。最后东海黑潮的最大流速和流幅也存在季节变化:夏季最大,秋季最小,春季和冬季居中。

Based on the CTD data of PN Section provided by Japanese Oceanographic Data Center,the current velocity of ninety cruises during 1991 to 2011are calculated with dynamic height method.The structure,maximum velocity,flux and width of the current are analyzed.The results show that there are three kinds of typical current structure of Kuroshio at PN Section,which are single core structure,double-core structure and multi-core structure.The occurrence probability of single core,double-core and multi-core are 50%,39%and 11%respectively.The current structure of Kuroshio at PN section exhibits significant seasonal variation.In autumn,the probability of occurrence of multi-core structure reaches its maximum,and the quarterly average of current core number is greater than other seasons.In winter,multi-core structure never emerges and single core structure occurs more often than any other structures,and the quarterly average of current core number is less than other seasons.All kinds of current structure occur in spring and summer.The quarterly average of current core number of spring and summer are between autumn and winter.The flux of Kuroshio at PN Section exhibits seasonal variation too.The flux reaches the largest in winter and summer,and smallest in autumn.Seasonal variation also occurs in maximum velocity and current width of Kuroshio at PN Section,which are the largest in summer and the smallest in autumn,followed by spring and winter.