  The surface current response to winds is analyzed in a two-year time series
of a 12 MHz (HF) Wellen Radar (WERA) off the West coast of France. The measured
currents, with tides filtered out, are of the order of 1.0 to 1.8% of the wind
speed, in a direction 10 to 40 degrees to the right of the wind. This
Lagrangian current can be decomposed as the vector sum of a quasi-Eulerian
current U_E, representative of the top 1 m of the water column, and a part of
the wave-induced Stokes drift Uss at the sea surface. Here Uss is estimated
with an accurate numerical wave model, thanks to a novel parameterization of
wave dissipation processes. Using both observed and modelled wave spectra, Uss
is found to be very well approximated by a simple function of the wind speed
and significant wave height, generally increasing quadratically with the wind
speed. Focusing on a site located 100 km from the mainland, the estimated
contribution of Uss to the radar measurement has a magnitude of 0.6 to 1.3% of
the wind speed, in the wind direction, a fraction that increases with wind
speed. The difference U_E of Lagrangian and Stokes contributions is found to be
of the order of 0.4 to 0.8% of the wind speed, and 45 to 70 degrees to the
right of the wind. This elatively weak quasi-Eulerian current with a large
deflection angle is interpreted as evidence of strong near-surface mixing,
likely related to breaking waves.
