| 摘要: |
| 为考察长江三峡工程对河口区生态环境的影响，有必要探讨长江径流量的季节变化对河口区及口外陆架区流场结构的影响。在“长江三峡工程对长江口区流场的影响”的一文(本集)中，作者己着重探讨了三峡工程的流量调节方案将给长江口区流场带来的可能影响。本文试图从长江径流量的季节变化来分析长江口外陆架海域海流结构的季节变化，从而为三峡工程流量调节方案的设计提供某些依据。
关于长江口区及其邻近陆架海域的海流结构问题，根据实测海流资料所作的分析，迄今为止，主要限于洪水季节(即夏季)(乐肯堂，1987，1986，1984;赵保仁，1982;上海航道局设计研究所，1978;中国科学院海洋研究所，1977;华东师范大学地理系河口海岸研究室，1975,1973; Le Kentang，1986；Cannon, et al. , 1983; Beardsley et al.，1983)。长江口区枯水季节(冬季)的海流结构曾已讨论(Le Kentang, 1988)。至于春、秋两季，迄今尚未见有专题论述。本文将根据已收集到的实测余流资料(其中包括1959-1976年的资料，1980-1981年间的中美联合考察资料和1985-1986年的专题调查资料)，结合有关的水文观测资料，对本区各个季节余流的结构作一初步的分析。 |
| 关键词: 长江口、外海流结构、季节变化 |
| DOI： |
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| 基金项目:中国科学院海洋研究所调查研究报告第2056号 |
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| CURRENT STRUCTRES AND THEIR SEASONAL VARIATIONS OFF THE CHANGJIANG RIVER MOUTH |
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Le Kentang, Yu Zhenjuan, Zhang Fagao
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Institute of Oceanology, Academia Sinica
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| Abstract: |
| The current structures of the Changjiang River Plume in the flood, dry and transitional seasons are briefly analyzed by using data from anchor stations obtained since 1950s. The main results are as follows: (1)In the flood season, there exists a jet-like flow area off the North Passage, where the maximum speed of the observed residual current could reach 103cm/s at the surface layer and the Changjiang Diluted Water( CDW)goes in such a way that it usually runs southeastward to eastward nearby the river mouth at first and then diverts to the northeast. (2) In the dry season the CDW is confined to a narrow band west of 122°33'E, extends to the south or southeast off the South Passage, and at the surface layer behaves like a quasi-geostrophic current instead of a jet-like current.(3) In the transitional seasons (spring and autumn) the main current speeds within the CDW are much less than that in the flood and dry seasons and its behaviour seems to be unstable. (4) The difference of the current structures for different seasons owes its origin to the seasonal differences of the monthly averaged discharge of the Changjiang River and its partitions in three branches-North Passage North Channel and South Channel. (5) The instability of the current structure in the nearshore section is caused by interaction between local wind field. coastal current. the Taiwan Warm Current and particularly, monthly averaged discharges in the above three branches over the complex topography. |
| Key words: CHANGJIANG RIVER MOUTH,CURRENT STRUCTRES,THEIR SEASONAL VARIATIONS |
