On the effect of the North Atlantic Oscillation on temperature and salinity of the subpolar North Atlantic intermediate and deep waters
Shirshov Institute of Oceanology, 36 Nakhimovskiy Prospect, 117997 Moscow, Russia
Received 15 August 2008; accepted 18 February 2009; advance access publication 17 April 2009.
Abstract
The close relationship between the observed water mass properties and the winter North Atlantic Oscillation (NAO) index (1950–2000s; r2 
0.65) implies that changes in the NAO-related atmospheric forcing may account for up to two-thirds of thermohaline changes at the intermediate and deep levels in the subpolar North Atlantic on a decadal time-scale. Persistent NAO decline (amplification) results in increase (decrease) in temperature and salinity in the intermediate–deep water column. A general mechanism explaining the close link between the NAO and coherent decadal changes in the intermediate and deep-water temperature and salinity in the region is inferred from the observed changes in the regional circulation and water mass properties. Two factors dominate this link: (i) intensity of convection in the Labrador Sea controlling injection of relatively cold freshwater into the intermediate layer, and (ii) zonal extension of the Subpolar Gyre that regulates the relative contribution of cold fresh subpolar water and warm saline subtropical water to the deep-water formation.
0.65) implies that changes in the NAO-related atmospheric forcing may account for up to two-thirds of thermohaline changes at the intermediate and deep levels in the subpolar North Atlantic on a decadal time-scale. Persistent NAO decline (amplification) results in increase (decrease) in temperature and salinity in the intermediate–deep water column. A general mechanism explaining the close link between the NAO and coherent decadal changes in the intermediate and deep-water temperature and salinity in the region is inferred from the observed changes in the regional circulation and water mass properties. Two factors dominate this link: (i) intensity of convection in the Labrador Sea controlling injection of relatively cold freshwater into the intermediate layer, and (ii) zonal extension of the Subpolar Gyre that regulates the relative contribution of cold fresh subpolar water and warm saline subtropical water to the deep-water formation.
Key words: Labrador Sea Water, long-term changes, North Atlantic Oscillation, overflow, Subpolar Gyre, Subtropical Gyre
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Sarafanov, A. 2009. On the effect of the North Atlantic Oscillation on temperature and salinity of the subpolar North Atlantic intermediate and deep waters. ICES Journal of Marine Science, 66: 1448–1454.
Link to abstract: http://icesjms.oxfordjournals.org/cgi/content/abstract/66/7/1448
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