Hydrodynamic dataset from the UPCAST and CASSISED campaigns in the Cassidaigne canyon (NW Mediterranean Sea)

In the Gulf of Lions, Northwestern Mediterranean Sea, the Cassidaigne submarine canyon is located in an active circulation area. Water movements are modulated both by westerly and easterly winds and by the Northern Current's mesoscale structures. The Cassidaigne canyon interacts with the general circulation inducing locally complex hydrodynamic processes. In 2017 and 2019, two oceanographic cruises were carried out in the Cassidaigne canyon area to gather current and temperature data. 2 ADCPs were moored on the shelf at 100 m depth around the canyon head, and 3 ADCPs were moored along the canyon axis from its head at 400 m depth to the base of the continental slope at 1900 m depth. STBD turbidimeters were moored in the canyon head and gorge to quantify sediment transport in the canyon. In addition, three Mastodon-2d thermistor lines were moored around the canyon head. Current measurements revealed a local circulation modulated by the morphology of the canyon depending on the stratification. Cross-canyon currents were recorded during Northern Current intrusion events. Temperature measurements revealed the generation of upwelling events under strong westerly winds. Near the bottom, these in-situ measurements revealed turbidity currents related to the canyon internal hydrodynamics.