Regional Impacts of Offshore Windfarming on the Hydro- and Ecosystem Dynamics in the North Sea

The production of renewable offshore wind energy in the North Sea increases rapidly, including development in ecologically significant regions. Recent studies identified implications like large-scale wind wake effects and mixing of the water column induced by wind turbines foundations. Depending on atmospheric stability, wind wakes imply changes in momentum flux and increased turbulence up to 70 km downstream, affecting the local conditions (e.g. wind speed, cloud development) near offshore wind farms. Atmospheric wake effects likely translate to the sea-surface boundary layer and hence influence vertical transport in the surface mixing layer. Changes in ocean stratification raise concerns about substantial consequences for local hydrodynamic and biogeochemical processes as well as for the marine ecosystem.
Using newly developed wind wake parametrisations together with the unstructured-grid model SCHISM and the biogeochemistry model ECOSMO, this study addresses windfarming impacts in the North Sea for future offshore wind farm scenarios. We focus on wind wake implications on ocean dynamics as well as on changes in tidal mixing fronts near the Dogger Bank and potential ecological consequences. At this, we create important knowledge on how the cross-scale wind farm impacts can be modelled suitably on the system scale.