基于FVCOM数值模拟和观察资料的长江冲淡水转向机制分析

Analysis of Direction Change Mechanism of the Changjiang River Diluted Water based on FVCOM and Observation

应用FVCOM海洋模式,建立长江口附近海域海洋模型。通过径流、风场、潮汐、斜压和背景流场等不同环境因素下的数值模拟并结合"我国近海海洋综合调查与评价"专项长江口区域的调查资料进行分析,对长江冲淡水的扩展情况进行研究。数值实验再现了长江冲淡水在夏季的转向现象,通过实验对比分析发现长江冲淡水的转向主要是受风场控制,其中斜压效应、潮汐潮流、背景流场对冲淡水的转向影响不明显。长江径流和潮汐潮流只影响长江口附近的较小区域,背景流场本身比较稳定,对长江冲淡水扩展的季节变化影响不大,斜压效应在长江冲淡水转向过程中所起作用较小。

A numerical model near the Changjiang River estuary was established based on FVCOM.A few numerical experimentations were conducted by different input condition,such as river discharge amount,wind,tide,baroclinic mode and background current.A series of analyses of direction change mechanism of the Changjiang River diluted water were taken by using the model result and observed data.It is shown by contrast different model results that the main external forces to make the diluted water turn to the northeast is the south wind.River discharge amount,tide and background current play quite an inconspicuous role in the direction changing process.River discharge amount and tide can only affect a small area near the estuary.Because of the stability of it,background current is not a main force for direction changing process.Baroclinic mode does not affect the path of diluted water too much.