基于潮波运动三维数值模拟的海洋连续深度基准面建立方法研究

Study on the establishment of the oceanic continuous chart datum based on three-dimensional numerical simulation of tidal wave motion

海洋深度基准作为海洋深度起算的垂直基准,对海洋大地测量、海洋物理调查等科研活动具有重要意义.鉴于传统的海洋深度基准面存在离散、非连续等缺陷,本文开展了基于潮波运动三维数值模拟的海洋连续深度基准面构建方法研究.研究结果显示,本文采用的有限体积的海岸海洋三维潮波运动模式FVCOM,具有构建三角格网灵活,可精确适用于不规则海岸边界的特点,并在地形特征较典型区域——长江口南支水域为实验区,开展了三维潮波运动的数值模拟.模拟所得各个格网节点处的平均潮差较好地符合了当地潮汐动力作用变化的规律,并以平均潮差为基础进一步建立了连续深度基准面,同南支区域6个已知深度基准的长期验潮站相比,深度基准面最大差值为5.5cm,差值绝对值均值为2.6cm,模拟结果内符合精度较高;且整个模拟所得的南支深度基准面的变化规律更符合长江口南支的潮汐变化特征.本文思想为海洋连续垂直基准的建立提供了一种新的思路,相比较于传统的几何插值拟合法,本文方法更具合理性和可靠性.

As the vertical datum for oceanic depth,chart datum is of great significance to scientific research activities such as marine geodetic survey and marine physical investigation.In view of the existence of discrete and discontinuous defects in the traditional ocean chart datum,this work studies the construction method of marine continuous chart datum based on three-dimensional numericalsimulation of tidal wave motion.The result indicates that the finite volume coastal oceanic model FVCOM has the characteristics of flexible construction of triangular lattice and can be applied to the irregular coastal boundary accurately.As a typical area of terrain features,the southern branch of the Yangtze River estuary was selected as the experimental area,and 3 Dnumerical simulation of tidal wave motion was carried out.The average tidal range at each grid node derived from FVCOM simulation is in good agreement with the local tidal dynamic,and a continuous chart datum is established on the basis of the average tidal range.Compared to the six long term tide gauges in the southern branch,the maximum difference of chart datum among them is 5.5 cm,with the mean difference value of 2.6 cm.Furthermore,the precision of simulation result is higher and more consistent with the tidal characteristic of the south branch of Yangtze River estuary.A new idea is provided in this paper for the establishment of marine continuous vertical datum,which is more rational and reliable when compared with the traditional geometric interpolation method.