Non-linear aspects of the tidal dynamics in the Sylt-Rømø Bight, south-eastern North Sea

Abstract

Abstract. This study is dedicated to the tidal dynamics in the Sylt-Rømø Bight with a focus on the non-linear processes. The FESOM-C model was used as the numerical tool, which works with triangular, rectangular or mixed grids and is equipped with a wetting/drying option. As the model's success at resolving currents largely depends on the quality of the bathymetric data, we have created a new bathymetric map for an area based on recent studies of Lister Deep, Lister Ley, Højer Deep and Rømø Deep. This new bathymetric product made it feasible to work with high-resolution grids (up to 2 m in the wetting/drying zone). As a result, we were able to study the tidal energy transformation and the role of higher harmonics in the domain in detail. For the first time, the tidal ellipses, maximum tidally induced velocities, energy fluxes and residual circulation maps were constructed and analysed for the entire bight. Additionally, tidal asymmetry maps were introduced and constructed. The full analysis was performed on two grids with different structures and showed a convergence of the results as well as fulfilment of the energy balance. A great deal of attention has been paid to the selection of open-boundary conditions, model validation against tide gauges and recent in situ current data. The tidal residual circulation and asymmetric tidal cycles largely define the circulation pattern, transport and accumulation of sediment, and the distribution of bedforms in the bight; therefore, the results presented in the article are necessary and useful benchmarks for further studies in the area, including baroclinic and sediment dynamics investigations.

Evaluation and Application of Newly Designed Finite Volume Coastal Model FESOM-C, Effect of Variable Resolution in the Southeastern North Sea

“…Previous work has demonstrated that the model can accurately reproduce tidal dynamics ( [25][26][27]). To test how the current model setup performs at reproducing the main tidal harmonics in long-term simulations, we analyzed observed sea-level height at several regional stations by extracting the amplitudes and phase of nine harmonics for comparison with model results.…”

“…Here, we present the results of simulations performed with the newly developed FESOM-C model [25,26]. FESOM-C is a coastal branch of The Finite-volumE Sea ice-Ocean Model (FESOM2) [1].…”

Plume spreading test case for coastal ocean models

“…FESOM-C is a coastal branch of the global Finite volumE Sea ice Ocean Model (FESOM2) (Danilov et al, 2017;Androsov et al, 2019;Kuznetsov et al, 2020;Fofonova et al, 2019). FESOM-C solves 3-D primitive equations in the Boussinesq, hydrostatic and traditional approximations for the momentum, continuity, and density constituents, and uses a terrain-following coordinate in the vertical.…”

Numerical and Data-Driven Modelling in Coastal, Hydrological and Hydraulic Engineering

“…Juznetsov et al [7] presented the results with a new 3D unstructured mesh finite volume coastal model, FESOM-C [12]. Over existing structured mesh models, FESOM-C with hybrid meshes (quadrilaterals and triangles) is geometrically flexible and allows the resolution of the mesh to be varied (within reasonable limits) in both the horizontal and vertical, letting the mesh contour complex coastlines.…”