Influence of wind-wave/swell interactions on the air-water momentum flux

The ocean surface is, more often than not, riddled with locally generated, growing wind-waves interacting with remotely generated swells. In moderate to high wind speeds, these complex interactions may strongly influence the occurrence of wave breaking as well as airflow separation events, which, in turn, control air-sea fluxes of momentum and scalars.

We present laboratory measurements of air and water dynamics in the vicinity of wind-modulated mechanically generated waves, at a 10 m fetch, using Particle Image Velocimetry. Using flow vorticity and turbulence estimates above and below the waves, we are able to quantify airflow separation and wave breaking events.

We observe modulations of the airflow by locally generated wind waves, including small sheltering events downwind of sharp wave crests. We will discuss the influence of local vs peak wind-wave conditions (e.g., wave age, slope), on wind-wave momentum and energy flux mechanisms.