东海南部水系分布和季节变化特征

Characteristics of Water Type Distribution and Seasonal Variation in the Southern East China Sea

利用中日黑潮联合调查研究期间“实践”号船1987年夏、冬季,1988年春、秋季的实测资料对研究海域的水系分布及其季节变化进行了分析研究。研究结果表明:(1)与大陆沿岸水性质相近的Ⅳ类混合水秋、冬季分布在大陆沿岸,春、夏季的范围向外海扩展。(2)黑潮水与陆架混合水的边界位置(称为黑潮水左边界)大致位于100～200m等深线之间,并随季节摆动,台湾东北海域,春季黑潮水边界靠近100m等深线,夏季靠近200m等深线,冬、秋季黑潮边界介于春、夏季之间。夏季底层,春季由表至底,黑潮水除了来自台湾以东海域外,还有部分来自台湾海峡。测区东北部R1断面附近,冬季黑潮水入侵陆架势力最强,边界偏西;夏季多数情况最弱,边界偏东;春、秋季位于二者之间。(3)黑潮水与陆架混合水之间有交错入侵现象.(4)陆坡附近多见黑潮水沿坡爬升现象,但有时相反,陆架混合水亦有沿坡下滑的情况。(5)从东南向西北水系的分布,并非完全按照K、Ⅰ、Ⅱ、Ⅲ、Ⅳ类水的顺序,有时出现水系跃变带,其位置也因时因地而异。

Based on the data of summer and winter 1987 and spring and autumn 1988 obtained by the ship 'Shijian 'during the China-apan Joint Survey on Kuroshio,the water type distribution and its variation are studied in the paper. The research findings indicate that (1) Grade Ⅳ mixing modification water type whose property is very close to that of the continental coastal water type is located along the coast of the continent in autumn and winter,but extends to the open sea in spring and summer; (2) The boundary between the Kuroshio water and the continental shelf mixing water (called the left boundary of Kuroshio water is located approximately between the 100 m and 200 m isobaths and its position varying with season. In the northeastern waters off Taiwan, the boundary of Kuroshio water is close to the 100 m isobath in spring, to the 200m isobath in summer while in autumn and winter, it is in between its positions in spring and summer. At the bottom in summer and from surface to bottom in spring, the Kuroshio water mainly comesfrom the sea area to the northeast of Taiwan with part of it from the Taiwan straits. Near the R section in the northeast part of the surveyed area, the intrusion of Kuroshio water is strongest in winter and the boundary is located to the west, while in most cases it is weakest in summer and the boundary is to the east. The boundary is between them in spring and autumns (3) There is crisscross intrusion between the Kuroshio water and the shelf mixing water; (4) There is an upwelling phenomenon of Kuroshio water along the continental slope, but sometimes, slipping down of the shelf mixing water along the slope may also occur; (5)Water type distribution from southeast to northwest is not entiarely in the order of water types K,Ⅰ ,Ⅱ , Ⅲ and Ⅳ , for sometimes there may occur a jumping zone of water type and its position varies with time and place.