2017: North Atlantic CMIP5

C. Heuzé (2017), “North Atlantic deep water formation and AMOC in CMIP5 models“, Ocean Science, vol 13, pp 609-622, doi:10.5194/os-13-609-2017

The North Atlantic version of my 2013 Antarctic bottom water paper. Assessment of the misrepresentation of North Atlantic deep water formation in 23 CMIP5 models, in order to easily see if the CMIP6 models have improved when they are released.

From Fig. 1: Models’ 1986-2005 mean winter mixed layer depth in the North Atlantic (shading) and winter/summer sea ice extent (green/magenta line). Not really better than in the Southern Ocean…

Most models form deep water too often, over too large an area which is not at the correct location, but a few were satisfying.
The main cause of this misrepresentation seems to be linked to the choice of sea ice model component.
Misrepresentation of deep water formation both in the North Atlantic subpolar gyre and in the Greenland-Iceland-Nordic seas impacts the Atlantic Meridional Overturning Circulation, which in turns impacts the heat exported into the Arctic.

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