桑沟湾邻近海域岬角潮余流涡对及其产生机理

Headland tidal residual eddies in the area adjacent to the Sanggou Bay and their generation mechanism

桑沟湾邻近海域潮余流对该海域物质输运具有重要作用,但由于观测资料不足的限制,该海域潮余流的整体分布状况尚不明确。本文利用22套锚系海流观测资料和高分辨率数值模拟资料,分析了桑沟湾邻近海域潮余流的整体分布特征,并探讨了其产生机理。桑沟湾内潮余流总体上较弱,其邻近海域的潮余流在3个岬角(俚岛,寻山和楮山)附近呈现出显著的潮余流涡对结构,每个岬角的北面存在气旋式潮余流涡,南面存在反气旋式潮余流涡。无论是流速大小还是涡覆盖范围,俚岛和楮山外海潮余流涡对均大于寻山外海的涡对。动力诊断分析表明,岬角附近3对潮余流涡的主要形成机制都是由侧边界摩擦引起的水平剪切作用,底摩擦应力旋度的作用只影响俚岛附近的潮余流涡对,位势涡度守恒的作用都不显著。

The tidal residual current in the adjacent area of Sanggou Bay plays an important role in material transport. However, due to the lack of observation data, the overall spatial pattern of the tidal residual current in this area is still unclear. 22 sets of observational data and high-resolution numerical simulation data of the ocean current were used to analyze the overall spatial characteristics of tidal residual currents and to reveal its formation mechanism. The tidal residual currents within the Sangou Bay are generally weak, while in the areas near the three headlands(Lidao, Xunshan and Chushan), the tidal residual currents show significant pair of eddies. To the northern part of each headland, there is a cyclonic tidal residual eddy;while to the southern part of each headland, there is an anticyclonic tidal residual eddy. The pair of eddies near the headlands of Lidao and Chushan are much stronger and cover wider area than those of Xunshan. Dynamic diagnosis based on the residual vorticity equation shows that the tidal residual eddies are mainly induced by the horizontal shearing due to the lateral boundary friction, the bottom friction stress curl only affects the tidal residual eddies near the headland of Lidao, and the effect of potential vorticity conservation is not significant in the formation process of the all three pair of the tidal residual eddies.