Labrador Slope Water connects the subarctic with the Gulf Stream

Abstract Labrador Slope Water (LSLW) is a relatively fresh and cool water mass that originates from the Current in subarctic known to occur Eastern Sea on US-Canadian shelf-slope north of Gulf Stream. It has potential densities 27.4–27.65 kg m −3 . Using ocean observations, we show here LSLW penetrates as boundary current deeply into Western (west 66°W) salinity minimum between 400 600 m, bringing it close proximity with The at Line W (near 69°W) also spreads across, brings fresher thicker waters to, A high-resolution model simulation shows spreading occurs throughout entire through extrusion fine-scale filaments following interaction Stream meanders eddies. At W, found be 2003 2008, when Atlantic Meridional Overturning Circulation (AMOC) 26°N higher (by 3 Sv), Shelf Front further south 0.7°), compared AMOC low conditions 2009–2014. causes lighter isopycnals rise over shelf slope, increasing lateral density gradient contributes an additional 1.3 Sv transport. These changes are likely result enhanced flow Sea, caused by wind stress subpolar gyre. transport (as opposed deeper Water) thereby offers new mechanism for decadal variability climate system, connecting subsequent AMOC.