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Atmospheric forcing during 2009–2010 and 2010–2011 winter months showed differences in both intensity and persistence that led to distinct oceanographic responses. Persistent dry northern winds caused strong heat losses (14 211 W m⁻²) in winter 2009–2010 that triggered a pronounced sea surface cooling compared to winter 2010–2011 (1597 W m⁻² lower). As a consequence, a large volume of dense shelf water formed in winter 2009–2010, which cascaded at high speed (up to ∼ 1 m s⁻¹) down Cap de Creus canyon, as measured by current-meters in mooring lines deployed inside the canyon at 300 m and 1000 m water depth. The lower heat losses recorded in winter 2010–2011, together with an increased river discharge, resulted in lowered density waters over the shelf, thus preventing the formation of dense shelf water. Particle fluxes were concurrently measured by using sediment traps at the same mooring stations. High total mass fluxes (up to 84.9 g m⁻² d⁻¹) recorded in winter 2009–2010 indicate that dense shelf water cascading resuspended and transported sediments at least down to 1000 m deep within the canyon. Sediment fluxes were lower (28.9 g m⁻² d⁻¹) under the quieter conditions of winter 2010–2011. The dominance of the lithogenic fraction in mass fluxes during the two winters points to a resuspension origin for most of the particles transported down canyon. The variability in organic matter and opal contents relates to seasonally controlled inputs associated to the plankton spring bloom during March and April of both years. Our measurements of particle fluxes (including major components and grain size distribution), together with meteorological and oceanographic parameters such as wind speed, turbulent heat flux, near-bottom water temperature, current speed and suspended sediment concentration, during winters 2009–2010 and 2010–2011 along the Cap de Creus submarine canyon, show the important role of atmospheric forcings in transporting particulate matter through the submarine canyon and towards the deep sea

Abstract. Particle fluxes (including major components and grain size), and oceanographic parameters (near-bottom water temperature, current speed and suspended sediment concentration) were measured along the Cap de Creus submarine canyon in the Gulf of Lions (GoL; NW Mediterranean Sea) during two consecutive winter-spring periods (2009–2010 and 2010–2011). The comparison of data obtained with the measurements of meteorological and hydrological parameters (wind speed, turbulent heat flux, river discharge) have shown the important role of atmospheric forcings in transporting particulate matter through the submarine canyon and towards the deep sea. Indeed, atmospheric forcing during 2009–2010 and 2010–2011 winter months showed differences in both intensity and persistence that led to distinct oceanographic responses. Persistent dry northern winds caused strong heat losses (14.2 × 103 W m−2) in winter 2009–2010 that triggered a pronounced sea surface cooling compared to winter 2010–2011 (1.6 × 103 W m−2 lower). As a consequence, a large volume of dense shelf water formed in winter 2009–2010, which cascaded at high speed (up to ∼1 m s−1) down Cap de Creus Canyon as measured by a current-meter in the head of the canyon. The lower heat losses recorded in winter 2010–2011, together with an increased river discharge, resulted in lowered density waters over the shelf, thus preventing the formation and downslope transport of dense shelf water. High total mass fluxes (up to 84.9 g m−2 d−1) recorded in winter-spring 2009–2010 indicate that dense shelf water cascading resuspended and transported sediments at least down to the middle canyon. Sediment fluxes were lower (28.9 g m−2 d−1) under the quieter conditions of winter 2010–2011. The dominance of the lithogenic fraction in mass fluxes during the two winter-spring periods points to a resuspension origin for most of the particles transported down canyon. The variability in organic matter and opal contents relates to seasonally controlled inputs associated with the plankton spring bloom during March and April of both years.

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