The Role of Wave‐Induced Stress and Drag Coefficients in Offshore Wind Power Production

Abstract

Abstract This study investigates wind‐wave interactions on offshore wind energy production by comparing a coupled atmosphere‐wave model (WRF‐SWAN) with a stand‐alone atmospheric model (WRF). Using statistical metrics and LiDAR wind measurements from Porto‐Ilha, Brazil, we evaluate the model's ability to capture wind variability and air‐sea momentum flux at an offshore wind farm site. The coupled WRF‐SWAN outperforms the stand‐alone WRF, particularly in representing wind‐wave dynamics and sea surface roughness. The BEM is a physically distinct and under‐explored air–sea interaction domain, where persistent trade winds coexist with long‐period North Atlantic swell, producing a bimodal wind–wave regime. Consistent with established observational and modeling evidence, under low wind speeds and strong swell, wave‐induced stress acts upward, transferring momentum from the ocean surface to the atmosphere and locally enhancing wind speeds. This momentum transfer depends on wind‐wave alignment, positive when aligned and negative when opposed. Corroborating established theory and observations, wave growth under moderate to strong winds ( m ) increases sea surface roughness and drag coefficient , leading to wind speed reductions at hub height. In swell‐dominated environments, when the wind follows the swell, a reduction in is observed, resulting in a positive bias in wind speed profiles. At the OWF site, WRF–SWAN configuration estimates up to 6% higher energy production than the stand‐alone WRF, emphasizing the importance of accurately representing wave‐induced stress and drag coefficients. These results highlight the potential of coupled atmosphere‐wave modeling to enhance offshore wind resource assessments, particularly in complex sea states off Brazil's coast.