Deep water formation and exchange rates in the Greenland/Norwegian Seas and the Eurasian Basin of the Arctic Ocean derived from tracer balances

Abstract

Multi-tracer data sets collected in the Greenland/Norwegian seas and the Eurasian Basin of the Arctic Ocean in the 1970s and 1980s are used, together with temperature and salinity, to (1) constrain box model calculations of the deep water formation rates in the Greenland Sea and the Eurasian Basin of the Arctic Ocean, and (2) estimate the exchange rates of deep waters (depth ≥1,500m) between the Greenland/Norwegian Seas and the Eurasian Basin. We obtain deep water formation rates of 0.1Sv (since 1980) to 0.47Sv (from at least 1965 to 1980) for the Greenland Sea, and 0.3Sv for the Eurasian Basin of the Arctic Ocean. The southward flux of Eurasian Basin Deep Water through Fram Strait is estimated to be about 1Sv. About 0.12Sv of this flux are transported into the Greenland Sea, about 0.37Sv reach the deep Norwegian Sea through the Jan Mayen Fracture Zone, and about 0.39Sv leave the Arctic Ocean through a shallower core which more or less directly feeds into the Iceland Sea, and, after modification, eventually ends up in the overflow waters. The outflow of Eurasian Basin Deep Water is balanced by deep water formation in the Arctic Ocean and by inflow of Norwegian Sea Deep water. About 0.77Sv of deep water formed in the Greenland Sea and the Eurasian Basin contribute to the formation of North Atlantic Deep Water. Uncertainties of the fluxes are estimated to be roughly ±20 to 30%.