The Sicily Channel surface circulation revisited using a neural clustering analysis of a high‐resolution simulation

Abstract

International audienceThe Sicily Channel surface circulation is investigated by analyzing the outputs of a high-resolution ocean model MED12 forced during 46 years by the ARPERA atmospheric fields. Applying a neural network classifier, we show that the surface circulation in the Sicily Channel can be decomposed into 8 modes characterizing the major patterns of that circulation, particularly the Algerian Current separation at the entrance to the Sicily Channel, the features of the Atlantic Tunisian Current and of the Atlantic Ionian Stream. These modes reflect the variability of the circulation in space and time at seasonal and inter-annual scales. Some modes preferably occur in winter whilst others are characteristic of summer. The mode sequence presents an inter-annual variability in good agreement with observations. The topography of the Sicily Channel sill plays a major role in steering the circulation. In particular the summer upwelling along the southern coast of Sicily, which is present in several modes, could be explained by a large-scale density forcing. A combination of barotropic/baroclinic double Kelvin waves generated on both sides of the sill provides a mechanism for explaining the complexity of the surface circulation advecting the surface waters from the Western Mediterranean toward the Eastern Mediterranean, the most salient features of which are the Atlantic Tunisian Current, the Atlantic Ionian Stream and the Tyrrhenian Sicilian Current which is a new feature highlighted by the present study

The Medieval Climate Anomaly in the Mediterranean Region

“…In addition, two marine cores show a warm first half of the MCA and a cold second half (sites 43 and AA43). Some of the cold MCA sites might be related to upwelling that seasonally and locally takes place in the Tyrrhenian Sea (Marullo et al, ; Perilli et al, ), Sicily Channel (Jouini et al, ), Gulf of Taranto (Pinardi et al, ), Adriatic Sea (Tijani et al, ), and Ionian Sea (Bakun & Agostini, ). Nevertheless, the percentage of reported sites with a cold MCA in Italy is clearly higher than in the Western Mediterranean, possibly pointing to a more regional pattern.…”

Interannual Variations of Surface Currents and Transports in the Sicily Channel Derived From Coastal Altimetry

“…A similar BATC/SG coupling is detectable in 1999-2000, but with no effect on the mean AW outflow, as well as an intensification of the SG in 1998-1999. This interannual variability mode of the AW flow over the SC is identified in Jouini et al (2016) from a neural cluster analysis of a 46 years Mediterranean circulation simulation (NEMO 1/128). Their analyses revealed a very significant signal for this circulation mode during summer 1999, 2003, and 2011, consistent with our findings.…”

“…Nevertheless, many questions still remain open about the interannual component of the SC surface circulation. Numerical modeling studies have mostly focused on a restricted part of the Central Mediterranean (e.g., Jouini et al, 2016;Pinardi et al, 1997), while sparse in situ based studies remain spatially limited to the SC entrance (e.g., Ben Ismail et al, 2012, 2014Sammari et al, 1995) or to the northwestern part of the channel (e.g., Bonanno et al, 2014). The previous works of Buongiorno Nardelli et al (1999Nardelli et al ( , 2006 have demonstrated the potential of standard altimetry for the estimate of currents inside the SC.…”

Marine ecosystems and living resources in the Central Mediterranean Sea: an introduction

“…It represents only 0.82% of the ocean surface and is considered a miniaturized ocean (Béthoux et al, 1999;Lejeusne et al, 2010), where nearly 17,000 marine species and 4-18% of global marine biodiversity are present (Coll et al, 2010). It is known to have a complex thermohaline, wind, and water flux-driven multi-scale circulation with interactive variabilities (Robinson et al, 2008;Jouini et al, 2016). The general water masses circulation in the Mediterranean has been described in detail (e.g., Hopkins, 1985;Pinardi & Masetti, 2000;Robinson et al, 2008), and is composed of three predominant and interacting spatial scales: basin scale (including the thermohaline circulation), sub-basin scale, and mesoscale (Robinson et al, 2008).…”

“…Both the permanent and non-permanent character of the recognized physical features of the Central Mediterranean, as well as its degree of variability, have been studied (e.g., Olita et al, 2007;Gasparini et al, 2008;Drago et al, 2010;Placenti et al, 2013;Ben Ismail et al, 2014;Bonanno et al, 2014a;Jouini et al, 2016). Some studies singled out the influences of environmental variability on the biological resources in the Central Mediterranean (e.g., Levi et al, 2003;Garofalo et al, 2010;Rjeibi et al, 2010;Basilone et al, 2013Basilone et al, , 2015Basilone et al, , 2017Bonanno et al, 2013Bonanno et al, , 2014bBonanno et al, , 2015Fiorentino et al, 2013;Khoufi et al, 2014;Barra et al, 2015;Jaziri et al, 2015;Lauria et al, 2016;Gargano et al, 2017).…”