珠江口及邻近海域潮波数值模拟——Ⅰ模型的建立和分析

Three-Dimensional High-Resolution Numerical Study of the Tide and Circulation in the Pearl River Estuary and Its Adjacent Waters Part Ⅰ:Model Building and Analysis

采用无结构网格三维有限体积海洋模式FVCOM,基于高精度的水深和岸线资料,建立了覆盖珠江口及邻近海域的三维正压高分辨率数值模型。和验潮站实测资料以及前人研究的对比验证表明,该模型能较准确地再现珠江口及邻近海域的潮汐、潮流变化过程。研究发现,珠江口海域潮汐为不正规半日潮,潮型数大致介于1.1~1.3之间,M2分潮占主导地位。M2,S2,K1和O14个主要分潮向河口内传播时,等振幅线均偏西北-东南向,西侧振幅小于东侧,河口附近等位相线比陆架海域密,西侧相较于东侧更密。从湾口传播到湾顶,半日分潮历时约2h,全日分潮历时约1.3h。潮流呈东强西弱,且落急流速大于涨急流速,河口内潮流流速是陆架海域的1~2倍,最大可达到1m/s;在陆架海域半日分潮旋转潮流强于全日分潮,在珠江口内主要为西北-东南方向往复流,航道区潮流最大。欧拉余流在河口内航道区形成南向流,在河口西侧浅滩处形成北向流,出现了余环流结构。此外,在航道区和深圳湾等区域形成较强余流涡旋结构。外海传入潮流能通量自南向北在珠江口内汇聚,在航道区呈现高值区,最大可达10KW/m。

Based on an unstructured grid and finite-volume coastal ocean model（FVCOM）,including highly accurate coastline and bathymetry data,a three-dimension model with high resolution is constructed in the Pearl River Estuary and its adjacent sea area to reproduce tides,tidal currents and residual currents.The comparison between observations and numerical modeling indicates that the computing results fit the measured values well.More elaborate co-tidal charts and pictures of tidal current ellipse of the four principal tide constituents as well as figures of tides,tidal currents and residual currents illustrate characteristics of tides and circulation in the research areas.The results show that there is mixed semidiurnal tide existing in the Pearl River,and the tide-type factor ranges from 1.1to 1.3.In the estuary,the tidal amplitude in the east side is higher than that in the west side,and the tide in the east propagates more quickly than that in the west;the tidal currents is mainly northwestern and southeastern with a rectilinear-current motion,and the maximum current velocity appears in the channel;the residual current in the channel flows towards the south,influenced by drainage of the runoff,while in the western shoal of the estuary,it flows towards the north,where a structure of circulation emerges.The tidal energy flux propagating from open sea,the maximum of which appears in the west and east channel of the estuary,mostly converges in the Pearl River Estuary,and circles counterclockwise around Qi＇ao Island.