Chapter 5 - The circulation and transformations of Atlantic water in the Arctic Mediterranean Sea

Abstract

In the previous two chapters we have described how the observational basis and the theoretical understanding of the circulation and transformations of the water masses in the Arctic Mediterranean Sea have grown and deepened during the century following the Fram drift 1893–96. Herein we examine observations that are available today and from these try to deduce what processes have been active in modifying the properties of the waters in different areas of the Arctic Mediterranean and if and how the conditions may have changed during the last 30 years. Most water masses present in the Arctic Mediterranean have entered from the North Atlantic by crossing the Greenland–Scotland Ridge; after following separate loops in the different basins in the Arctic Mediterranean they return, either as dense overflow water or low-salinity Polar surface water across the ridge to the North Atlantic. It is therefore natural to follow the Atlantic water along its different pathways, how it splits and becomes transformed by cooling and freezing, melting and freshwater input into different water masses. Some of these waters remain permanently separated, but some again meet and interact creating new waters. In addition to the cul-de-sac circulation of the Atlantic water, there is a throughflow of Pacific water from Bering Strait through the Canadian Arctic Archipelago and Baffin Bay to the Labrador Sea. The Atlantic and the Pacific waters do not follow completely separate paths but interact in the Beaufort Gyre, and some Atlantic water passes through the Canadian Arctic Archipelago to the Labrador Sea and some Pacific water, occasionally at least, becomes part of the East Greenland Current and crosses the Greenland–Scotland Ridge into the North Atlantic.