On the Impact of Long Wind-Waves on Near-Surface Turbulence and Momentum Fluxes

We propose a new phenomenological model to represent the impact of wind-waves on the dissipation of turbulence kinetic energy near the sea surface. In this model, the momentum flux at a given height results from the averaged contribution of eddies attached to the sea surface whose sizes are related to the surface geometry. This yields a coupling between long wind-waves and turbulence at heights of about 10 m. This new wind-and-waves coupling is thus not exclusively confined to the short wave range and heights below 5 m, where most of the momentum transfer to the waves is known to occur. The proposed framework clarifies the impact of wind-waves on Monin–Obukhov similarity theory, and the role of long wind-waves on the observed wind-wave variability of momentum fluxes. This work reveals which state variables related to the wind-wave coupling require more accurate measurements to further improve wind-over-waves models and parametrizations.

Keyword(s)

Air-sea fluxes, Wall-bounded turbulence, Wave boundary layer, Wind stress, Wind-waves

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Ayet Alex, Chapron Bertrand, Redelsperger Jean-Luc, Lapeyre Guillaume, Marié Louis (2020). On the Impact of Long Wind-Waves on Near-Surface Turbulence and Momentum Fluxes. Boundary-layer Meteorology. 174 (3). 465-491. https://doi.org/10.1007/s10546-019-00492-x, https://archimer.ifremer.fr/doc/00601/71285/

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