大亚湾海域潮流和余流的三维数值模拟

Three-dimensional numerical simulation of tidal current and residual current at Daya Bay

用三维陆架海模式(HAMSOM)对大亚湾海域的潮汐、潮流和余流进行了数值模拟研究,模拟结果与实测值吻合较好。给出了潮流性质、主要分潮的潮流椭圆和余流。计算结果表明,大亚湾海域的潮流性质以不正规半日潮为主,水平潮流具有明显的往复流性质,主要呈南-北方向,落潮流速比涨潮流速大,其中表层M2分潮最大流速为25.3cm.s-1。流速受地形的影响,在大辣甲和黄毛山岛之间以及两岛与岸之间的区域流速较大,尤其在湾的东北角狭长地形处流最急,流速最大;靠近岸边流速较小,水平速度的垂向变化不大。夏季湾内余流较小,海域自净能力较弱。冬季湾内水体的自净能力随流场强度加强而加强。

A three-dimensional shelf sea model （HAMSOM） is employed to simulate the tide, tidal current and residual current at the Daya Bay. The computed results agree well with the observed ones. The cotidal chart, tidal nature, tidal ellipses of the main component and residual current are given. It is shown that the tide at the Daya Bay is mainly irregular semidiurnal. The horizontal tidal flow reciprocates obviously in the south-north direction. The flow speed of ebb tide is greater than that of flood tide. The maximum flow velocity of M2 tide component is 25.3 cm · s^-1. The flow is affected by the topography, with the larger flow speed occurring at the narrow area among the mainland, the Dalajia island and the Huangmaoshan island and the smaller one near the coast. The horizontal velocity changes little vertically. As the residual current within the bay is relatively small in summer, the self-purification capacity of this sea area is weak; whereas it is stronger in winter with the stronger current fields.