Stability of North Atlantic Deep Water formation in a global ocean general circulation model

Abstract

A global ocean GCM is forced using mixed boundary conditions. Freshwater flux anomalies lasting 5 years are then applied over the western half of the subpolar gyre in the northern North Atlantic. The current climate is found to be stable to anomalies that have salt deficits equivalent to about seven times that estimated for the "great salinity anomaly' of 1968-1982. Above this level the thermohaline circulation collapses to a state in which the zonally averaged overturning associated with North Atlantic Deep Water formation is only about half its original value, SSTs over the North Atlantic are lowered, and both the subpolar and subtropical gyres have weakened horizontal transports. -from Authors