夏季长江口外东海海域实测海流资料分析

Analysis of the Summertime Current Observations Outside of the Yangtze Estuary in Donghai

根据2009年8,9月间长江口外海域C1,B1 2个站位的短期连续ADCP实测资料,采用调和分析、EOF分解、功率谱分析以及频率统计等方法,分析了该海域海流随时间的变化趋势和空间的结构特征。结果表明,2个站位流速在观测期间愈来愈强,准定常流动均是南向流动占优。长江口外海域M2为主要分潮,属于正规半日潮,各层潮流呈现出旋转流性质,旋转方向为顺时针占优。2个站位潮流的U,V分量均为第一模态主导,其垂向模态基本一致,体现了潮流的正压特征,2个站位的斜压性均不明显。海流的流速、流向频率统计显示两站均在SSE,S,SSW方向的频率最大。

Based on the successive acoustic Doppler current profiler（ADCP） observations at 2 stations located outside of Yangtze estuary from August to September 2009,by the methods of Tidal Current Harmonic Analysis（TCHA）,EOF,Fast Fourier Transform（FFT） and frequency statistics.The current trend during the observed period and its spatial structure characteristics are analyzed,the results show that velocity at both stations gradually becomes larger during the observation period,and the quasi-steady current of V-component is dominant for both stations.M2 is the dominant partial tide in this area,which is in charge of regular semi-diurnal tide.The tidal current turns to be rotating current,mainly clockwise.By EOF analysis,we find that the first vertical modes of U and V of both 2 stations are dominant,which incarnates barotropic tidal current feature,while the tidal current seems weak in baroclinic feature.Statistics show that the largest frequencies occur in the SSE,S and SSW directions.