浙闽沿岸潮余流的空间变化

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0.6~2.5 cm/s,方向沿等深线指向西南;后者流速为0.5~1.5 cm/s,方向沿等深线指向东北。区域II的潮余流较弱,均小于0.6 cm/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ddx1H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。

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

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 0.6~2.5 cm/s and northeastward directions with a velocity of 0.5~1.5 cm/s, respectively. The TRCs in Region II are weaker (less than 0.6 cm/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 ddx1H, this is consistent with the previous studies, and indicates the rectification of tidal currents when they flow over the steep bottom topography.