Observations of a direct boundary current ventilation pathway

The subpolar North Atlantic is a known hotspot for anthropogenic carbon and oxygen uptake, however the detailed pathways for dissolved gasses into the deep North Atlantic remain poorly understood. While it is clear that high-oxygen waters formed by deep convection in basin interiors are exported southward by boundary currents, it has also been hypothesized that significant water mass transformation and associated gas exchange occurs near or within boundary currents themselves. Here we present novel year-round oxygen observations mounted on the Overturning in the Subpolar North Atlantic Program (OSNAP) moorings within the Irminger Sea’s western boundary current. These observations are the first to show direct boundary current ventilation to over 1000m depths following down-front wind events, revealing a previously underappreciated pathway for oxygen into the deep North Atlantic.