The circulation of the Denmark Strait and Iceland-Scotland overflow waters in the North Atlantic

Abstract

Abstract The bottom waters of the northernmost northeast Atlantic are derived from a dense outflow from the Norwegian Sea through the Faeroe Bank Channel. Near-still mixing increases the salinity and lowers the dissolved oxygen content of the outflow, but when the mixed water later enters the northwest Atlantic through the Charlie-Gibbs Fracture Zone, it is freshened and oxygenated by mixing with the denser, lower-salinity overflow water from Denmark Strait. The end product contributes to a deep tongue of relatively saline, oxygen-rich water that has been traced in other studies throughout much of the World Ocean. This study traces the saline tongue from its origin in the Faeroe Bank Channels to the deep waters south of the Grand Banks. The relatively close coupling of the deep northern North Atlantic with the sea surface in the Greenland, Iceland, and Norwegian seas makes this region potentially responsive to changes introduced at the sea surface, though this study shows no significant temperature and salinity changes in the deep water over the 1957 to 1973 period emphasized in the analysis.