Numerical Prediction of Wind Waves and Related Air-Sea Fluxes

Wind-waves are important for air-sea interaction as they directly influence the exchange of mass, momentum and energy between the ocean and the atmosphere. Wave breaking plays a particularly important but poorly quantified role in these processes. During the Gulf of Tehuantepec Experiment (GOTEX), conducted in February 2004, we collected standard meteorological measurements along with surface-wave measurements using a scanning lidar (Airborne Topographic Mapper, ATM), and a downward-looking video camera on the NSF/NCAR C-130 aircraft during fetch-limited conditions. The Gulf of Tehuantepec is well known for having strong offshore winds during the winter time, when an atmospheric pressure difference develops between the Gulf of Mexico and the Pacific Ocean, forcing winds through a mountain gap at the head of the gulf. We present a direct comparison between the observed evolution of the wave field and numerical simulations using a state-of-the-art wind-wave model. In particular, we compare wave breaking statistics as measured from video images to those derived from model simulations using several versions of the breaking dissipation function. We discuss our results in the context of previous observations and models, and the influence of breaking on air-sea fluxes.