风场对夏季长江口外东北海域低盐水团的作用  

Impact of wind on the low-salinity water lens in the northeast out of the Changjiang estuary in summer

作　　者：彭剑[1] 朱首贤[2] 李训强[1] 张文静[1] 周中刚[1] 

机构地区：[1]解放军理工大学气象海洋学院,南京211101 [2]河海大学港口海岸与近海工程学院,南京210098

出　　处：《华东师范大学学报（自然科学版）》2014年第3期105-116,共12页Journal of East China Normal University(Natural Science)

基　　金：国家自然科学基金(40906044;41076048);中央高校基本科研业务费项目(2011B05714)

摘　　要：长江冲淡水对黄东海水文环境有重要影响,它主要以羽状形态向外海扩展,在某些年份的特殊时间段也存在孤立的低盐水团现象.观测资料表明,1976年8月没有低盐水团,1977年8月在长江口外东北海域有低盐水团.本文的数值模拟解释了这些现像.这两年7月底至8月初径流量和天文潮强度相当,在7月21日—8月4日都存在较强的偏南风过程.本文分析了1976年夏季较强偏南风过程没有产生低盐水团的动力机制.1976年夏季较强偏南风过程及其南东南风向,兼有使冲淡水向东北扩展和向北顶托切割冲淡水的作用,有利于形成低盐水团.但是,1976年7月26日—30日的偏南风最强阶段是大潮转小潮时间,这种时间配置不利于形成低盐水团,它是没有低盐水团的主要原因.1976年较强偏南风的风场强度比1977年略弱,对低盐水团的促进作用也弱一些,但它不是没有低盐水团的主要原因.本文的研究结果可以对某些年份夏季存在较强偏南风过程、没有低盐水团的现象给予解释.The expansion of the Changjiang diluted water （CDW） is a dominant hydrographic phenomenon in the East China Sea, which is mainly in the shape of plume. However, there are also some low-salinity lenses （LSWLes） in partial time of some years. The observations show that there wasn＇t LSWL in August 1976 while there was in August 1977. The numerical simulations in this paper explained these phenomena. The strength of tide from the end of July to August in 1976 was similar with that in 1977, so as the runoff. And there were both processes ofstrong leaning south wind from July 21 to August 4. Then the mechanism why there wasn＇t LSWI. during the process of the strong leaning south wind in summer 1976 is analyzed. The strong leaning south wind and its direction of south-south-east were helpful for pushing CDW northeastward and cutting it to form LSWL. The strongest leaning south wind was from July 26 to 30 when it was the time from neap tide to spring tide, which was the main reason of no LSWL. And the strong leaning south wind was slightly weaker in 1976 than that in 1977, thus it didn＇t made so significant effect on LWSL formation as that in 1977.

关 键 词：长江冲淡水 低盐水团 风场 动力机制 数值模拟 

分 类 号：P731[天文地球—海洋科学]