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

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 numerical simulation 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 3D numerical 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.