The use of a wave boundary layer model in SWAN

Abstract

AbstractA wave boundary layer model (WBLM) is implemented in the third‐generation ocean wave model SWAN to improve the wind‐input source function under idealized, fetch‐limited condition. Accordingly, the white capping dissipation parameters are recalibrated to fit the new wind‐input source function to parametric growth curves. The performance of the new pair of wind‐input and dissipation source functions is validated by numerical simulations of fetch‐limited evolution of wind‐driven waves. As a result, fetch‐limited growth curves of significant wave height and peak frequency show close agreement with benchmark studies at all wind speeds (5–60 m s−1) and fetches (1–3000 km). The WBLM wind‐input source function explicitly calculates the drag coefficient based on the momentum and kinetic energy conservation. The modeled drag coefficient using WBLM wind‐input source function is in rather good agreement with field measurements. Thus, the new pair of wind‐input and dissipation source functions not only improve the wave simulation but also have the potential of improving air‐sea coupling systems by providing reliable momentum flux estimation at the air‐sea interface.