Water exchanges between the Tyrrhenian Sea and the Liguro-Provençal basin occur through the Corsica Channel, a narrow passage between Corsica and the Elba Island, near the Italian coast. It has long been known that the Channel hosts a robust Tyrrhenian outflow in winter, which penetrates far into the Ligurian Sea, reaching the site where deep-water formation takes place. The summer circulation in the area, and, more generally, in the eastern part of the Ligurian Sea, is less well known. Several experimental and modelling works in the last decade have pointed out the presence of an anticyclone in the Channel area, sometimes referred to as Ligurian anticyclone, which could modulate the exchanges between the two basins in summer, and could strongly affect the dispersion properties in the south-eastern Ligurian Sea, with implications on the local, delicate marine environment. In this work, we focus on this structure, and on the role it plays in the local circulation, seeking information from long datasets of satellite observations (sea level, sea surface temperature and turbidity) that are now available. We find that the Ligurian anticyclone is a recurrent feature of the local circulation in summer. Its core is located between Cap Corse (the peninsula at the northern end of Corsica) and the Elba Island, but the anticyclone may extend till the Italian coast, and it may sometimes be more elongated in the latitudinal direction, and/or more displaced towards north. In some years, a companion anticyclonic vortex is found more to the north, in the north-eastern portion of the Ligurian Sea, but the robustness of this structure is unclear. Analysis of the ERA5 winds indicates that the Ligurian anticyclone is likely driven by an area of negative wind stress curl usually present near Cap Corse in summer, even though contributions from the surrounding circulation cannot be a priori excluded.
Aspects of the summer circulation in the eastern Ligurian Sea
Iacono R.;Napolitano E.
2020-01-01
Abstract
Water exchanges between the Tyrrhenian Sea and the Liguro-Provençal basin occur through the Corsica Channel, a narrow passage between Corsica and the Elba Island, near the Italian coast. It has long been known that the Channel hosts a robust Tyrrhenian outflow in winter, which penetrates far into the Ligurian Sea, reaching the site where deep-water formation takes place. The summer circulation in the area, and, more generally, in the eastern part of the Ligurian Sea, is less well known. Several experimental and modelling works in the last decade have pointed out the presence of an anticyclone in the Channel area, sometimes referred to as Ligurian anticyclone, which could modulate the exchanges between the two basins in summer, and could strongly affect the dispersion properties in the south-eastern Ligurian Sea, with implications on the local, delicate marine environment. In this work, we focus on this structure, and on the role it plays in the local circulation, seeking information from long datasets of satellite observations (sea level, sea surface temperature and turbidity) that are now available. We find that the Ligurian anticyclone is a recurrent feature of the local circulation in summer. Its core is located between Cap Corse (the peninsula at the northern end of Corsica) and the Elba Island, but the anticyclone may extend till the Italian coast, and it may sometimes be more elongated in the latitudinal direction, and/or more displaced towards north. In some years, a companion anticyclonic vortex is found more to the north, in the north-eastern portion of the Ligurian Sea, but the robustness of this structure is unclear. Analysis of the ERA5 winds indicates that the Ligurian anticyclone is likely driven by an area of negative wind stress curl usually present near Cap Corse in summer, even though contributions from the surrounding circulation cannot be a priori excluded.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
