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Abstract

The Mediterranean Sea is a semi-enclosed marginal sea characterized by a rapid overturning circulation (Millot & Taupier-Letage, 2005) where deep-water formation processes happen in both the western and eastern basins (Schroeder et al., 2012 and references therein, Pinardi et al., 2019). In the northwestern Mediterranean Sea, the intermediate water masses are characterized by a temperature and salinity maximum in subsurface corresponding to the Levantine Intermediate Waters (LIW) formed in the eastern basin in late February/early March (Lascaratos et al., 1993). This saline and relatively warm water mass spreads at intermediate depths (between 200 and 600 m) over the Mediterranean in a westward pathway, entering the Ligurian Sea and flowing within the Northern Current along the southern French coasts on its way to the Strait of Gibraltar. During its transit from the eastern basin, the consumption of organic matter sinking from the surface decreases the O 2 content in this water mass creating an O 2 minimum in the water column (160-170 μmol kg −1 , Coppola et al., 2018) and lowering pH T and increasing dissolved inorganic carbon (C T ; Álvarez et al., 2014). In the northwestern Mediterranean Sea, which is well ventilated compared to the global ocean (Schneider et al., 2014), Dense Water Formation (DWF) mainly occurs in the Gulf of Lion (Herrmann et al., 2010;Somot et al., 2018), where winter