Large-Scale Vertical and Horizontal Circulation in the North Atlantic Ocean

Abstract

Observations of large-scale hydrography, air?sea forcing, and regional circulation from numerous studies are combined by inverse methods to determine the basin-scale circulation, average diapycnal mixing, and adjustments to air?sea forcing of the North Atlantic Ocean. Dense overflows through the Denmark Strait and Faroe Bank channels are explicitly included and are associated with strong vertical and lateral circulation and mixing. These processes in the far northern Atlantic play a fundamental role in the meridional overturning circulation for the entire ocean, accompanied by an upper cell of mode-water and intermediate-water circulation. The two cells converge roughly at the mean depth of the midocean ridge crest. The Labrador Sea Water layer lies within this convergence. South of the overflow region, model-derived mean diapycnal diffusivities are O(10?5 m2 s?1) or smaller at the base of the thermocline, and diapycnal advection is driven primarily by air?sea transformation on outcropping layers.