Impact of wave-dependent stress on storm surge simulations in the North Sea: Ocean model evaluation against in situ and satellite observations

We investigate the impact of wave-dependent stress on surge modelling, from case studies in the North Sea, using a global ocean model forced with a wave-atmosphere coupled model. We select the storms with the largest surges and a range of sea state development from young to mature seas. The modelled surges are compared to tide gauges and altimeter data. The ocean model is able to accurately predict storm surges in coastal areas. The consistency of the model outputs, the altimeter, and the tide gauge data confirms the accuracy of altimeters for storm surge measurements. We show that using a wave-dependent rather than a wind-dependent only stress formulation gives more accurate surge simulations when the sea state is young and the sea rougher. Taking into account the waves in the stress formulation has a significant impact on the surges (up to 20 cm).