Surprising return of deep convection to the subpolar North Atlantic Ocean in winter 2007-2008

Type Article
Date 2009
Language English
Author(s) Vage Kjetil1, Pickart Robert S.1, Thierry VirginieORCID2, Reverdin Gilles3, Lee Craig M.4, Petrie Brian5, Agnew Tom A.6, Wong Amy6, Ribergaard Mads H.7
Affiliation(s) 1 : Woods Hole Oceanog Inst, Woods Hole, MA 02543 USA.
2 : IFREMER, CNRS, IRD,UMR 6523, UBO,Lab Phys Oceans, F-29280 Plouzane, France.
3 : Lab Oceanog Dynam & Climatol, FR-75252 Paris, France.
4 : Univ Washington, Appl Phys Lab, Seattle, WA 98105 USA.
5 : Fisheries & Oceans Canada, Bedford Inst Oceanog, Dartmouth, NS B2Y 4A2, Canada.
6 : Meteorol Serv Canada, Downsview, ON M3H 5T4, Canada.
7 : Danish Meteorol Inst, DK-2100 Copenhagen, Denmark.
Source Nature Geoscience (1752-0894) (Nature), 2009 , Vol. 2 , N. 1 , P. 67-72
DOI 10.1038/NGEO382
WOS© Times Cited 140
Note Campagne OVIDE
Abstract In the process of open-ocean convection in the subpolar North Atlantic Ocean, surface water sinks to depth as a distinct water mass, the characteristics of which affect the meridional overturning circulation and oceanic heat flux. In addition, carbon is sequestered from the atmosphere in the process. In recent years, this convection has been shallow or non-existent, which could be construed as a consequence of a warmer climate. Here we document the return of deep convection to the subpolar gyre in both the Labrador and Irminger seas in the winter of 2007-2008. We use profiling float data from the Argo programme to document deep mixing. Analysis of a variety of in situ, satellite and reanalysis data shows that contrary to expectations the transition to a convective state took place abruptly, without going through a phase of preconditioning. Changes in hemispheric air temperature, storm tracks, the flux of fresh water to the Labrador Sea and the distribution of pack ice all contributed to an enhanced flux of heat from the sea to the air, making the surface water sufficiently cold and dense to initiate deep convection. Given this complexity, we conclude that it will be difficult to predict when deep mixing may occur again.
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Vage Kjetil, Pickart Robert S., Thierry Virginie, Reverdin Gilles, Lee Craig M., Petrie Brian, Agnew Tom A., Wong Amy, Ribergaard Mads H. (2009). Surprising return of deep convection to the subpolar North Atlantic Ocean in winter 2007-2008. Nature Geoscience, 2(1), 67-72. Publisher's official version : , Open Access version :