Global Temperatures | City Temperatures | Ocean Overturning

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Atlantic Thermohaline circulation. From the CLIVAR website.

Cold water is known to sink to the region to the west and east of Iceland (dark blue arrows) and drives the deep ocean circulation around the world. It is thought that the volume of sea ice exiting the Arctic into the Greenland Sea influences the rate of sinking. This sinking and the returning surface waters (shown in red and orange) is referred to as the North Atlantic Overturning.

Shown in the image to the right are "the pathways associated with the transformation of warm subtropical waters into colder subpolar and polar waters in the northern North Atlantic. Along the subpolar gyre pathway the red to yellow transition indicates the cooling to Labrador Sea Water, which flows back to the subtropical gyre in the west as an intermediate depth current (yellow). In the Norwegian and Greenland Seas the red to blue/purple transitions indicate the transformation to a variety of colder waters that spill southwards across the shallow ridge system connecting northern Europe, Iceland, Greenland, and northern North America. These overflows form up into a deep current also flowing back to the subtropics (purple), but beneath the Labrador Sea Water. The green pathway also indicates cold waters--but so influenced by continental runoff as to remain light and near the sea surface on the continental shelf." (from Oceanus Magazine).

Find more information (references and websites)

• The Atlantic heat conveyor slows, by Detlef Quadfasel, Nature 438, 565-566 (1 December 2005) | doi:10.1038/438565a (Click for PDF)
• The thermohaline circulation, by Tim Osborn, from the Climate Research Unit at the University of East Anglia
• North Atlantic's Transformation Pipeline Chills and Redistributes Subtropical Water, from Oceanus
• Atlantic Thermohaline Circulation, from CLIVAR
• North Atlantic circulation and water masses. Thermohaline forcing, by Lynne Talley, Scripps Institution of Oceanography