The Role of Freshwater Variability in North Atlantic Subpolar Climate Dynamics

The North Atlantic Subpolar region is a critical region for global climate dynamics, serving as a gateway between the subtropical and Arctic zones. This region is characterized by intense atmosphere-ocean interactions, where water masses meet and undergo transformation, influencing ocean circulation. Recent studies have highlighted a phenomenon of freshening in the Subpolar North Atlantic, with potential implications for regional climate and ocean circulation. Given the complex interactions between the ocean, atmosphere, and cryosphere, uncertainties remain regarding the underlying causes and future climate impacts. In this study, we utilize new historical simulations from a state-of-the-art global climate model, to investigate how variations in salinity are linked to changes in large-scale atmospheric circulation. Our composite analysis of extreme years reveals that freshwater anomalies in the subpolar gyre are closely associated with cooler sea surface temperatures and atmospheric pressure anomalies over Western Europe. These findings suggest that freshwater fluxes could have significant, far-reaching effects on both regional climate and the broader North Atlantic climate system.