Untangling the relationship between AMOC variability and North Atlantic upper-ocean temperature and salinity

A maximum covariance analysis applied to a 1,201-year preindustrial control simulation reveals two leading modes that separate these two distinct roles of North Atlantic temperature and salinity as related to AMOC variability.

A linear combination of the two modes accounts for most of the variation of a widely used AMOC index. The same analysis applied to another control simulation known to possess two distinct regimes of AMOC variability-oscillatory and red-noise-suggests that the North Atlantic buoyancy-forced AMOC variability is present in both regimes but is weaker in the latter, and moreover there is pronounced multidecadal/centennial AMOC behavior in the latter regime that is unrelated to North Atlantic buoyancy forcing.