Advancing Ocean Modelling in the Open-to-Coastal Ocean: An Online-Coupled Coastal Application to Assess Multi-use in the Southern North Sea

Modelling oceanic processes in shallow coastal domains presents challenges that are not encountered in open-ocean oceanography, due to strong land-sea interactions and non-linear physical processes. The Horizon Europe FOCCUS project (Forecasting and Observing the Open-to-Coastal Ocean for Copernicus Users) addresses some of these challenges by strengthening the (open) ocean–to–coastal ocean interface through enhanced in-situ and satellite observations, improved hydrological and land-ocean products, and advanced coupling between oceanic and coastal models, whilst exploring data assimilation and machine learning techniques. These developments are demonstrated across twelve coastal applications located in all European oceans.

In this contribution, we present one of these coastal applications based on the Dutch Continental Shelf Model (DSCM), a Delft3D-Flexible Mesh implementation covering the north-western European shelf with a focus on the southern North Sea. The model utilises an unstructured grid to resolve hydrodynamics and sediment transport, and explicitly represents offshore wind farm infrastructure, treating turbines as large, rigid obstacles that interact with the flow. Hydrodynamics, sediment transport and water quality are fully online-coupled and linked to aquaculture modules to assess productivity and yield potential for mussel and seaweed cultivation at offshore wind sites.

Within FOCCUS, the existing framework is improved in three ways: I) through the addition of thermobaric effects to the equation of state, II ) by using enhanced hydrological model results as river inputs and III) by using gap-filled satellite observations as an initial sediment field. The enhanced coupled framework is applied to investigate interactions between offshore wind farms, aquaculture activities, and their combined impacts on water quality in the Southern North Sea. This application demonstrates how unstructured-grid, observation-informed coastal models can support integrated blue economy assessments and reduce uncertainty in operational and strategic decision-making for shallow coastal seas.

FOCCUS is funded by the European Union (Grant Agreement No. 101133911). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Health and Digital Executive Agency (HaDEA). Neither the European Union nor the granting authority can be held responsible for them.