Weather maintained thermohaline circulation

A new mechanism is presented to explain the existence and maintenance of high subpolar salinities in the North Atlantic. The mechanism relies on the existence of strong meridional excursions of the atmospheric Jet Stream over the North Atlantic, which, through dynamical oceanic adjustment (passive oceanic response to the winds), lead to an efficient homogenization of salinity between the saltier subtropical and fresher subpolar gyres. This “atmospheric mixer” is studied in an idealized two-gyre model and an intermediate complexity coupled climate model.

Considering the tight relationship between subpolar salinities and strength of the Atlantic meridional circulation, it is proposed that the atmospheric mixer mechanism is instrumental in maintaining a stable and vigorous Atlantic overturning.