Abstract

Ocean ventilation and subduction are key processes regulating the transport of water from the mixed layer to the ocean’s interior, which is isolated from the atmosphere for a timescale set by the large-scale circulation. Using numerical simulations, we assess where the ocean subducts water and takes up properties from the atmosphere, and how ocean currents transport and redistribute these properties. This is achieved by using passive tracers that are released annually from different ocean surface “patches”, representing water masses’ source regions. We show that interannual variability in subduction rates, driven by changes in surface forcing, is key in setting the different sizes of the long-term inventory of the dyes. Both hemispheres exhibit a strong correlation between the strength of ventilation in recently subducted waters and the longer-term dye inventory. Export and isolation of subducted waters is faster in the Northern than Southern Hemisphere, defining a stronger ventilation “persistence”, especially at high latitudes (e.g. Labrador and Irminger Sea). I will focus on both the subpolar North Atlantic and Subantarctic Mode Water source regions.