Observation-Based Dissipation and Input Terms for Spectral Wave Models, with End-User Testing

Abstract

The long-term goal is to implement input and dissipation source functions, based on advanced understanding of physics of air-sea interactions, wave breaking and swell attenuation, in waveforecast models. OBJECTIVESThe objectives are to use new observation-based source terms for the wind input, wave-breaking (whitecapping) dissipation and swell decay in the third-generation models WAVEWATCH-III and SWAN. Calibration and performance of the source functions have to satisfy a set of physical constraints, and the methodology is developed to enable testing the source functions separately before they are blended in the full model. Verification is conducted by means of academic tests and hindcasting real-life scenarios defined by the end users from the US Navy, Army and NOAA, to include deep and finite-depth conditions, closed seas (no swell) and open ocean, extreme weather events, and global simulations. APPROACHPhysics of two primary source/sink terms employed by the operational models, namely wavebreaking energy dissipation and wind-to-wave energy input had not been updated for decades. In the meantime, the new physics is available. For the first time under field conditions, in the course 1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.