珠江口外海水声速经验正交函数分析

利用珠江口外海多年的水文观测资料,采用经验正交函数(EOF)法分别对该海域表层及21°N垂向断面的声速及其距平值进行了分析.结果表明该海域表层声速自西北向东南增大,21°N垂向断面声速随水深的增加而减小.EOF法分析声速及其距平值得出的第一个特征分量在该区域表层和21°N垂向断面上都是最重要的.声速季节变化显著:自上一年的10月开始减小,2或3月减到最小值后开始增大,7~9月增至最大值,有显著的年变化周期.声速也似有年际变化:1981年冬季声速开始减小,一直持续到1982年秋季,1982年冬季开始呈增大的趋势.声速的年际变化强度随着水深的增加而减弱.

An analysis of sound velocity in waters off Zhujiang River estuary with the empirical orthogonal function (EOF)

Based on the data of temperature,salinity and depth obtained for a longer time series off Zhujiang River estuary waters,distribution and variability of sound velocity in sea water is analysed with the empirical orthogonal function.Sound velocity in seawater increases from northwest to southeast in the surface and decreases with the increase of water depth vetically.The analysis results of the empirical orthogonal function show that the first mode,both sound velocity and its mean deviation,are the most important.Sound velocity of water has evident seasonal variation.It decreases from October around,and drops to the leastest in February or March before getting larger.It rises to the largest in July and September.Sound velocity in sea water looks like an inter-annual variability too and its tensity decreases with increasing water depth.