OSNAP: Overturning in the Subpolar North Atlantic Program

Cold Arctic waters meet warm waters carried poleward by the Gulf Stream in the North Atlantic Ocean, where they mix and are transformed by interactions with the Greenland Ice Sheet and atmosphere. These processes contribute to the large-scale Atlantic Meridional Overturning Circulation (AMOC), which plays a crucial role in regulating Earth’s climate. OSNAP (the Overturning in the Subpolar North Atlantic Program) is an international effort to observe and understand the variability of ocean circulation in this dynamic region. Since 2014, OSNAP has maintained a network of underwater moorings stretching from eastern Canada to Greenland and across to the UK. Moored instruments continuously measure temperature, salinity, and currents from the surface to the seafloor. This record provides novel insights into how heat, freshwater, and dissolved gases move through the North Atlantic and how this is linked to variability in the AMOC and global climate.