Abstract
<jats:p>The wavy sea surface as the site of atmospheric and oceanic interactions, is known to affect near-surface winds in the marine atmospheric boundary layer, with possible impacts on air-sea coupling at large scales for swell waves. However its precise effects on the near-surface wind profile is yet to be quantified. This study employs a 7-month dataset of 30 minute-averaged wind profiles from the sea surface up to 150 meters, from a Scanning Wind S-LiDAR located on Belle-Ile-en-Mer island. Nearby directional measurements of surface waves allow us to relate the observed wind profiles to sea state. We use this dataset to quantify the difference between observations and various idealised boundary layer profile parametrisations; notably log-law profiles corresponding to Monin-Obukhov Similarity Theory (defined via a constant flux layer) conditions without swell impact. Additional idealised profiles are also explored such as an boundary layer's outer layer, or a boundary layer including the Coriolis force.These differences between observation and idealised profiles are systematically studied according to environmental conditions (air and sea temperatures, representative wind speed and direction, wave-age, wave direction, height, and length, wave orbital velocities, and currents). In particular, swell dominant, low wind conditions likely to have the strongest impact on surface wind are studied in detail. Complementary cases of swell shoaling are also studied. They are used to modify existing parametrisation of a surface boundary layer representing the effect of swell (in deep water or shoaling) on surface turbulent fluxes and the wind profile.The parametrisation aims to provide more accurate winds in numerical weather predictions or atmospheric climate models.</jats:p>