A study of the sea level and current effects on the sea state in Galway Bay, using the numerical model COAWST

A coupled wave and ocean model is applied to the region of Galway Bay in the west of Ireland, using the numerical modelling suite COAWST. The coupled model was validated in a previous study. Here we focus on the impact of the currents and sea level on the sea state during Storm Hector (2018/06/14). The purpose of the research is to improve the wave dynamics knowledge specifically in Galway Bay by highlighting and quantifying the dominant current-induced mechanisms on the sea state observed numerically. We want to know where wave-current interaction is modifying the sea state in the bay, and if the change is significant to justify the use of a coupled model for an operational application. We show that the impacts of the tidal sea surface height on bottom friction and of the current-induced refraction on the spatial distribution of the waves are the dominant mechanisms. Those two effects are well-documented and observed in the literature already. A strong feedback impact of the coupling is also put into evidence. The wave-induced response in terms of currents leads to a noticeable variation in terms of wave height. Less documented in the literature, we discuss the link between current-induced refraction and the reduction of wave generation by wind.

Automated summary

A coupled wave and ocean model is used to investigate the impact of currents and sea level on the sea state in Galway Bay. The study aims to improve the understanding of wave dynamics and assess the suitability of the coupled model for operational applications.