Cessation and partial reversal of deep water freshening in the northern North Atlantic: observation-based estimates and attribution

Type Article
Date 2010
Language English
Author(s) Sarafanov Artem1, Mercier HerleORCID2, Falina Anastasia1, Sokov Alexey1, Lherminier PascaleORCID2
Affiliation(s) 1 : PP Shirshov Oceanol Inst, Moscow 117997, Russia.
2 : CNRS, UMR 6523, IFREMER, Lab Phys Oceans,UBO,IRD, Plouzane, France.
Source Tellus Series A: Dynamic Meteorology and Oceanography (0280-6495) (Wiley / Blackwell), 2010 , Vol. 62 , N. 2 , P. 80-90
DOI 10.1111/j.1600-0870.2009.00418.x
WOS© Times Cited 17
Note Campagne OVIDE
Abstract Recent decadal salinity changes in the Greenland-Scotland overflow-derived deep waters are quantified using CTD data from repeated hydrographic sections in the Irminger Sea. The Denmark Strait Overflow Water salinity record shows the absence of any net change over the 1980s-2000s; changes in the Iceland-Scotland Overflow Water (ISOW) and in the deep water column (Sigma(0) > 27.82), enclosing both overflows, show a distinct freshening reversal in the early 2000s. The observed freshening reversal is a lagged consequence of the persistent ISOW salinification that occurred upstream, in the Iceland Basin, after 1996 in response to salinification of the northeast Atlantic waters entrained into the overflow. The entrainment salinity increase is explained by the earlier documented North Atlantic Oscillation (NAO)-induced contraction of the subpolar gyre and corresponding northwestward advance of subtropical waters that followed the NAO decline in the mid-1990s and continued through the mid-2000s. Remarkably, the ISOW freshening reversal is not associated with changes in the overflow water salinity. This suggests that changes in the NAO-dependent relative contributions of subpolar and subtropical waters to the entrainment south of the Iceland-Scotland Ridge may dominate over changes in the Nordic Seas freshwater balance with respect to their effect on the ISOW salinity.
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Sarafanov Artem, Mercier Herle, Falina Anastasia, Sokov Alexey, Lherminier Pascale (2010). Cessation and partial reversal of deep water freshening in the northern North Atlantic: observation-based estimates and attribution. Tellus Series A: Dynamic Meteorology and Oceanography, 62(2), 80-90. Publisher's official version : https://doi.org/10.1111/j.1600-0870.2009.00418.x , Open Access version : https://archimer.ifremer.fr/doc/00000/7325/