Potential Fram Strait circulation feedback freshens the Arctic Ocean

In recent decades, the upper Arctic Ocean has become increasingly fresher; meanwhile, the northern hemisphere sea ice extent and thickness have reduced. An increase in meteoric freshwater fluxes and a decrease in the rate at which freshwater is transferred from the ocean to the sea ice are often considered the primary drivers of pan-Arctic Ocean freshening. The relative role of changes in the freshwater transports through ocean gateways has gained less attention, and coupled with the circulation changes that accompany it, are not fully understood. Here, we investigate multidecadal variations in gateway transports and their atmospheric and oceanic drivers in a large ensemble of fully-coupled historical CESM simulations and a comparable JRA55-do-forced ocean-sea ice simulation. We highlight the effect of gateway transports on the delicate balance between various sources and sinks of Arctic liquid freshwater, resulting in its accumulation. We show evidence of a potential Fram Strait circulation feedback that freshens the Arctic and illustrate the feedback mechanism within the forced ocean-sea ice simulation.