浙闽沿岸潮余流的空间变化

Spatial variation of the tidal residual currents in the coastal area off Zhejiangand Fujian Provinces in the East China Sea

利用非结构网格海洋环流模式（FVCOM）,研究了浙闽沿岸潮余流的空间变化及其生成机制。结果表明,浙闽沿岸的潮余流具有明显的水平二维特征。根据潮余流的流速和方向,浙闽沿岸的潮余流可分为3个区域,自东北向西南,依次为区域I、区域II和区域III。区域I和区域III的潮余流较强,前者流速为0.6~2.5cm/s,方向沿等深线指向西南;后者流速为0.5~1.5cm/s,方向沿等深线指向东北。区域II的潮余流较弱,均小于0.6cm/s,方向自岸向海逆时针旋转,离岸较近区域方向指向西南,离岸较远区域方向指向东北。结合浙闽沿岸的潮余流和海底地形进行分析,发现潮余流与地形β效应（d/dx）（1/H）成正比,这与前人研究获得的海底地形对潮流的整流机制相符合,表明浙闽沿岸海域陡峭的海底地形对潮流有明显的整流作用。

A detailed spatial structure of the tidal residual currents（TRCs）in the coastal area off Zhejiang and Fujian Provinces in the East China Sea was simulated by an unstructured grid-volume,three-dimensional,primitive equations ocean model（FVCOM）.The simulated TRCs have apparent horizontal 2-D characters.The TRCs were further divided into three regions from north to south according to their velocity and direction,i.e.,Region I,Region II and Region III.The TRCs in Region I and Region III are stronger but in opposite direction,flowing along isobaths in the southwestward with a velocity of 0.6~2.5cm/s and northeastward directions with a velocity of 0.5~1.5cm/s,respectively.The TRCs in Region II are weaker（less than 0.6cm/s）,and their directions are unticlockwise with the distance away from the coast.The analysis shows that the TRCs are directly proportional to the topographic beta factor（d/dx）（1/H）,this is consistent with the previous studies,and indicates the rectification of tidal currents when they flow over the steep bottom topography.