Temporal switching between sources of the Denmark Strait overflow water

The Denmark Strait overflow water derives from several distinct sources. Arctic Intermediate Water from the Iceland Sea, Atlantic Water of the West Spitsbergen Current recirculating in the Fram Strait, and Arctic Atlantic Water returning from the different circulation loops in the Arctic Ocean all take part in the overflow. Denser water masses, such as the upper Polar Deep Water and the Canadian Basin Deep Water from the Arctic Ocean and Arctic Intermediate Water from the Greenland Sea, are occasionally present at the sill and could contribute the deepest part of the overflow plume. A comparison between hydrographic observations made during the Greenland Sea Project in the late 1980s and early 1990s and during the European Sub Polar Ocean Programme (ESOP) and Variability of Exchanges in the Northern Seas (VEINS) programmes in the late 1990s shows that the Greenland Sea Arctic Intermediate Water has largely replaced the Arctic Ocean deep waters. In the less dense fraction of the overflow the Recirculating Atlantic Water and Arctic Atlantic Water carried by the East Greenland Current have become more prominent than the Iceland Sea Arctic Intermediate Water. If the Denmark Strait overflow were to switch between different sources, it would lead to changes in the characteristics of the overflow water that add to the variations caused by the variability of the source waters.

Article from Marine Science Symposia Vol. 219 - "Hydrobiological variability in the ICES Area, 1990-1999", symposium held in Edinburgh, 8-10 August 2001. To access  the remaining articles please click on the keyword "MSS Vol. 219".