U.S. Dept. of Commerce / NOAA / OAR / PMEL /Publications
The presence of a large body of saline deep water in the Arctic Ocean (Arctic Ocean deep water, or AODW), with a probable formative connection to the surrounding shelf seas, is by now well established [Aagaard, 1981; Swift et al., 1983; Aagaard et al., 1985], as is the outflow of this water to the Greenland Sea through western Fram Strait [Aagaard et al., 1985; Smethie et al., 1988; Swift and Koltermann, 1988]. This earlier work suggests that the importance of the saline Arctic Ocean outflow lies first and foremost in its contribution to the Norwegian Sea deep water (NSDW), which is now thought to be formed by mixing of the outflow with the Greenland Sea deep water (GSDW), thus providing a rather direct connection between the deep thermohaline circulation of the Arctic Ocean and that of the seas to the south.
Our purpose here is to shed further light on that connection, based principally on hydrographic measurements in the western Greenland Sea and Fram Strait during 1987. We find that several distinct saline Arctic Ocean sources contribute to the intermediate and deep hydrographic structure of the Greenland Sea, and that while much of the saline Arctic Ocean outflow recirculates in the Greenland Sea, a significant portion continues into the Iceland Sea. We also find clear evidence of mixing between GSDW and deep waters from the Arctic Ocean, including the production of NSDW; some of this production occurs in northern Fram Strait. Variability in the supply of source waters (either warm and saline AODW or cold and fresher GSDW) will lead to changes in the hydrographic structure of the Greenland and Norwegian seas. Such a situation appears to have occurred during the past decade, with reduced convection in the Greenland Sea (but persisting outflow from the Arctic Ocean) resulting in a warmer and less dense deep regime.
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