Wave–Current Interactions in a Wind-jet Region

Abstract

Abstract. Wave–Current Interactions (WCIs) are investigated. The study area is located at the northern margin of the Ebro Shelf (northwestern Mediterranean Sea), where episodes of strong cross-shelf wind (wind jets) occur. The aim of this study is to validate the implemented coupled system and investigate the impact of WCIs on the hydrodynamics of a wind-jet region. The Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system, which use Regional Ocean Model System (ROMS) and Simulating WAves Nearshore (SWAN) models, is used in a high-resolution domain (350 m). Results from uncoupled numerical models are compared with a two-way coupling simulation. The results do not show substantial differences in the water current field between the coupled and the uncoupled runs. The main effect observed when the waves are considered is in the water column stratification, due to the turbulent kinetic energy injection and the enhanced surface stress, leading a larger mixed-layer depth. Additionally, when the water currents are considered, the agreement of the modeled wave period significantly improves and the wave energy (and thus the significant wave height) decreases when the current flows in the same direction as the waves propagate.

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“…For instance, wave-current interactions can contribute to the generation of large-amplitude waves, triggered naturally when a stable wave train encounters an accelerating opposing current (Onorato et al, 2011). Ràfols et al (2019) drew a similar conclusion via numerical simulations with coupled (hydrodynamic-wave) models in the NW Mediterranean Sea. Viitak et al (2016) reported an increase of the wave height of up to 100 cm in nearshore waters of the eastern Baltic Sea, during the St. Jude storm, due to the combined effect of surface currents and sea level on the wave field evolution.…”