Current reversal and associated variability within the Corsica Channel: The 2004 case study

Flow reversals within the Corsica Channel, a strait East of Corsica, are investigated with a realistic, high-resolution (~1.5km) numerical setup simulating the year 2004. The simulations compare well with available water mass transport estimates resulting in an annual mean of 0.49±0.49Sv. Similarly, the model agrees with hydrographic observations in the area, and current velocity measurements showing a flow in the Corsica Channel predominantly directed northward from the Tyrrhenian to the Ligurian Sea. On top of the well-documented Corsica Channel seasonal variability, a higher-frequency variability can be found throughout the year but more frequently during the summer season. This temporal variability, highest close to the western flank of the Channel, is of the order of a few days to a week and associated with reversals of the currents. We find that this variability is ascribed to periodic intrusions of the West Corsica Current on the Eastern side of the Island. Moreover, our findings suggest the importance, of a so-far neglected, across-channel variability of the meridional velocity throughout the entire 2004. This result potentially questions the single-mooring assumption that has always been at the center of the observational scheme. This assumption holds while looking at low-frequency/seasonal variability but fails when focusing on higher-frequency variability.