闽江冲淡水扩展范围的季节变化特征

Seasonal variations of diluted water extension from Minjiang River

利用2006～2007年春、夏、冬季3个航次的CTD资料分析闽江冲淡水扩展范围季节变化特征.通过分析闽江口及邻近海域温度、盐度的平面、垂直分布特征,结果表明:闽江冲淡水的扩展范围具有明显的季节变化.春季由于闽江口附近受到闽浙沿岸流的影响,冲淡水的扩展范围难以确定,但从盐度分布情况不难看到闽江口表层被盐度低于25的具有明显冲淡水特征的水体覆盖.夏季闽江口被温度高于27℃、盐度低于25的冲淡水覆盖,冲淡水前沿向东北扩展至罗源湾、三沙湾.冬季闽江径流减弱,闽江口主要受到闽浙沿岸水的影响,基本看不到闽江冲淡水的痕迹.春季、夏季闽江冲淡水明显的影响闽江口时,闽江口附近海域被25盐度等值线包围,25盐度等值线可作为闽江口明显受冲淡水影响的指征.

In this paper,CTD data from 3 surveys in spring,summer and winter of 2006 and 2007 are used to analyze seasonal variations of the diluted water extension from Minjiang River.According to the study of the horizontal and vertical distribution of temperature and salinity,we found that Minjiang Diluted Water（MDW） has an obvious seasonal characters.In spring when Minjiang River Eestuary and its adjacent waters are affected by Fujian and Zhejiang coastal current,MDW is hard to determine.The salinity distribution shows that Minjiang River Estuary is covered by freshwater with salinity lower than 25.In summer,MDW,characterized by temperature higher than 27℃ and salinity lower than 25,covers the whole estuary and the front of MDW even extends to Luoyuan Bay and Sansha Bay.In winter when the runoff from Minjiang River reduced and waters of and off the estuary were dominated by Zhejiang and Fujian coastal current,MDW can hardly be found.In spring and summer when the estuary is significantly affected by MDW and surrounded by isohaline 25,the isohaline 25 can be characterized as the indicator of MDW.