Mediterranean outflow waters supply North Atlantic convection sites

The northward-flowing branch of the Mediterranean Outflow Water (MOW) carries warm and saline water into the Subpolar North Atlantic, where deep convection contributes to the formation of water masses that feed the lower limb of the Atlantic Meridional Overturning Circulation. Due to its distinctive thermohaline characteristics, the MOW presence may act as a preconditioning factor for the formation of these waters. However, the complex dynamics of the subpolar regions make tracing its pathway beyond ~50°N using conventional tracers and datasets challenging. We use an extensive dataset of Argo float salinity and oxygen profiles acquired over the North Atlantic during more than two decades to track the northward-flowing MOW and characterize its evolution along the way. Here we show that these observations allow for a multi-tracer approach, providing robust evidence of MOW’s presence in the subpolar basins, including the Irminger Sea, which has recently been identified as a basin where major deep convective processes occur. These findings highlight the potential role of the MOW in influencing the large-scale overturning circulation. Argo salinity and oxygen profiles in the North Atlantic are used to track the Mediterranean Outflow Water, providing evidence of its presence in the subpolar basins, where deep convective processes occur, and highlighting its role in influencing the large-scale overturning circulation.