The HF radar is the sole instrument being able to monitor the surface coastal current at very high spatial and temporal resolution. A radar system deployed since 2010 on the Var coast (Western Mediterranean Sea) provides for the first time a comprehensive picture of the circulation, which remains poorly documented in this area.Surface current mapping is conventionally performed by combining measurements of at least two radars. However, significant results were obtained with a single radar concerning: the identification of mesoscale vortices; the signature of periodic phenomena affecting the surface circulation in the diurnal, inertial and semi-diurnal bands; and the features and instabilities of the North Mediterranean Current (NC).The assimilation of radar measurements using an ensemble Kalman smoother in a regional model of the North-Western Mediterranean Sea was performed for the first time in the study area. This method, which constraints the surface currents by wind and open boundary conditions optimisation, improves the simulation of the NC vein in terms of speed and position.
