Deep-water renewal in the northern North Atlantic

Abstract

THE renewal of the deep water of the world's oceans is accomplished through the input of dense water in both the northern North Atlantic and around Antarctica but direct measurement of the renewal rate has proved elusive. Here we describe the first successful long-term measurement of the transport of the northern inflow component where it passes south along the Continental Slope off East Greenland. There we observe a cold, bottom-intensified, long-slope flow with maximum speeds of around 100 cm s-1, mean speeds of up to 25–30 cm s-1, a dominant fluctuation timescale of a few days period but with little seasonal or interannual variation in speed or direction. We estimate the transport at densities (σΘ)≥=27.80 to be stable at 10.7x 106 m3 s-1 and propose a circulation scheme for waters of this density throughout the northern gyre.