基于FVCOM的台湾海峡三维潮汐与潮流数值模拟研究

Three-dimensional tide and tidal current numerical simulation based on FVCOM in Taiwan Strait

基于FVCOM海洋数值模式,采用非结构三角形网格较好地刻画了台湾海峡复杂的岸线边界及海底地形,建立了台湾海峡的三维潮汐潮流数值模型.模拟结果同长期观测资料符合良好,较好地反映出台湾海峡内潮汐、潮流运动的变化状况和分布特征,利用T_tide工具包进行水位潮流调和分析给出了M2、S2、K1、O1四个主要分潮的同潮图、表层潮流椭圆分布.分析表明,M2分潮由台湾岛南北两端传入台湾海峡,两支潮波在澎湖—台湾浅滩南缘相遇,呈NE—SW向倾斜,振幅最大值为2.45m,出现在福建省湄洲湾、兴化湾一带.K1分潮潮波由东北向西南传入,并向南海传播,传播方向上右侧振幅较左侧大0.05m.台湾海峡存在一条分潮潮流椭圆率为0的分隔线,该分隔线大致呈NE—SW走向,分隔线上半部分潮流椭圆旋转方向为逆时针方向,下半部分为顺时针方向.四个主要分潮潮流椭圆长轴基本呈NE—SW走向,但在台湾浅滩表层潮流椭圆长轴方向为NW—SE向,澎湖水道呈N—S向.台湾浅滩处四个分潮的潮流椭圆均较大,对应的潮流也强,可能受当地水深较浅的影响.

A 3-D hydrodynamic model is established used an unstructured triangular grid known as the finite-volume coastal ocean model（ FVCOM） to resolve the irregular coastline and bathymetry in the coastal regions. The simulated results are in good agreement with the long-term observed data and reproduce the distribution features of the tide and tidal currents in Taiwan Strait. The distributions of co-tidal charts and tidal ellipse on the surface layer for 4major constituents（ M2、S2、K1、O1） are obtained by T_tide toolkit. The results show that the southward and northward tidal waves of M2 tide from the Pacific into Taiwan Strait converge between Penghu Islands and south of Taiwan Shoal in the direction of NE—SW and the maximum amplitude is 2. 45 m and it appeared in the areas of Xinghua bay and Meizhou Bay. K1 constituent incoming wave propagates from northeast to southwest toward the South China Sea,the amplitude of which in the right side of forward direction is 0. 05 m higher than the left＇s. There exists a dividing line on which the ellipticity of constituent tidal is zero in Taiwan Strait. The line direction is NE—SW,at the upper part of which the direction of rotation is counterclockwise,the lower is clockwise. Four major tidal currents to the major axis of the ellipse are in NE—SW direction and in the nearshore region and the discontinuous terrain such as Taiwan Shoal are in NW—SE direction,while in Penghu Channel they are in N—S direction. The major axes of 4 tidal currents in the Taiwan Shoal are large and the corresponding trend is also large due to the influences of local shallow depth.