The significance of tides for offshore wind wake effects on coastal ocean dynamics

As offshore wind development increases, marine environments are increasingly affected by offshore wind farm wakes and their impact on hydrodynamic processes. Recent studies have shown that wind wakes can influence ocean circulation and stratification through changes in surface wind speed. However, their results indicate that the wake effects are attenuated in areas that are strongly determined by tidal currents. In this study, we look deeper into the wake-induced hydrodynamic processes and the influence of tides, aiming to understand the role of local hydrodynamic conditions on the magnitude of emerging wake effects. For this, we use high-resolution unstructured-grid modeling, focusing on offshore wind development for tidal and non-tidal scenarios in the shallow North Sea. The model simulations show the effects arising from wind speed reductions and demonstrate the impact of tidal processes. We identified that tidal currents can disturb the changes in surface current velocity and even mitigate the impact on the mean flow field around offshore wind farms. In shallow waters, tidal stirring superimposes wake-induced processes and can influence the changes in vertical mixing and stratification. Our simulations reveal that tides eventually mitigate the impacts of offshore wind farm wakes on the North Sea hydrodynamics. These findings become important when assessing offshore wind farm effects in different marine environments and estimating the extent of the anthropogenic disturbances.