PNNL

Abstract

Wave energy is a highly promising source of marine renewable energy, and accurately characterizing and assessing wave energy resources is essential for effective site selection, permitting, and the development of wave energy converters. However, assessing wave energy in regions influenced by strong currents presents challenges due to the effects of wave-current interactions. This study introduces a two-way coupled wave-current interaction model with a 2 km spatial resolution, developed within the Coastal Ocean Atmosphere Wave Sediment Transport (COAWST) modeling framework, to address these challenges in wave resource characterization. The model encompasses the northeastern U.S. coastline, including the Mid-Atlantic Bight and the Gulf of Maine. It integrates WaveWatchIII (WWIII) and the Regional Ocean Modeling System (ROMS) to enhance wave hindcasting accuracy and improve wave energy resource assessments, accounting for current-induced Doppler shift, refraction, and nonlinear energy exchanges between wave and current fields. The model’s performance was evaluated by comparing its output with in-situ buoy measurements and satellite data. Using the validated model results, wave power density was assessed, and the impact of current-induced Doppler shift on power density was found to be up to 20%. The comparison further supports the hypothesis that accounting for nonlinear wave-current interactions in regions with strong current strain improves model performance in predicting wave climates. Analysis shows that a strong current gradient and shear can both interact with the wave field, reshaping wave crests by focusing/de-focusing or stretching/squeezing mechanisms, altering wave frequency and direction, and ultimately leading to changes in wave power density by up to 40% at synoptic time scale.