2006-2007年长江冲淡水的扩展形态及季节变化

利用2006—2007年观测的高密集度CTD测站和海床基ADCP连续测流站资料,分析了长江冲淡水的扩展形态和垂向结构。结果表明,各季节观测时段内:春季、秋季和冬季的表层长江冲淡水扩展基本被限制在长江口、杭州湾及舟山水域附近。夏季长江冲淡水的扩展由内向外可分为3个阶段:射形流阶段,长江径流直接向东南冲入海;水舌形态扩展阶段,冲淡水以1个水舌的完整形态指向东北,其运动受台湾暖流和南黄海海盆气旋式环流等背景流场的影响明显;扩散阶段,冲淡水先以较大团块运动,后以不断变小的水块随着背景流场运动,其中一支向东北移动进入南黄海,另一支转向东偏南,绕东海东北部冷涡运动。

The Extension Form and Seasonal Variation of the Changjiang Diluted Water During 2006--2007

The extension form and vertical structure of the Changjiang diluted water by the CTD and ADCP data are analyzed in the paper. The results indicate that the surface layer of Changjiang diluted water was limited in the Changjiang mouth, Hangzhou bay and Zhoushan in spring, autumn and winter. The extension of the Changjiang diluted water in summer can be divided into three st-ages, shooting shape flow stage, the Changjiang water ran southeast into the sea; water tongue-like extension stage, diluted water which was located between the south Yellow Sea cold water mass and continental shelf of the East Sea mixed water pointed to the northeast. Its movements were at the mercy of the Taiwan Warm Current and South Yellow Sea cyclonic circulation; diffusion stage, the diluted water first in the way of bulk water block, and then in the way of de- creasing water block following the background flow field. One branch moved northeast to the South Yellow Sea, another branch turned to southeast, moving in the way of cold eddy winding the northeast of the East Sea.