Variability of the Oceanographic Characteristics in the Subpolar North Atlantic Based on Data from Autonomous Buoys Argo and Hydrographic Sections
Pavel A Sultanov1
1Oceanology, Lomonosov Moscow State University, 141080, Russia, Moscow region, Korolev, Gorkoy street, 3, 61, Korolev, 141080, Russia, psultanov [at] gmail [dot] com
Weakening of the Global Conveyor is being predicted due to reduction of formation of complex multi-layer North Atlantic Deep Water (NADW). It includes Labrador sea water (LSW) involved into dense deep waters, coming from the North-European Arctic Basin.
4800 ARGO TS profiles in the Labrador Basin were analyzed to study the variability of upper 2000m through 2000-2009 due to climate changes. For the analysis of deep and intermediate water masses 7 interannual latitudinal transatlantic Russian cruises were used (program "Meridian Plus"). There were not found any evidences of occurring deep convection outside the Labrador Sea. The relationship of the intensity of convection and the North Atlantic Oscillation (NAO) was studied. It was proved, that important role in regulation of the convection depth pre-conditions play: ice situations and the wind field.
The results of this study showed that, contrary to the salinization trend and warming of water masses, observed in the region over the last decade, deep convection in the subpolar North Atlantic in the winter of 2007-2008 returned. Despite the fact that the index of the NAO in 2007-2008 was lower than previous year, a cooling and freshening of LSW were developed. According to Argo mixed layer depth was about 1600 m in the Labrador Sea, 800 m in the Irminger Sea and to the south of Greenland, which significantly exceeds the values for the past 14 years. TS time series based on Argo data from 2000 showed strong cooling and freshening of the core and the periphery of the LSW compared to the last decade.
For volume-thermohaline analysis Argo-climatology of Asia Pacific Data research center and WOA2005 were used.
Climate changes, reflected in the Arctic, need to be studied not only in the region, but on the periphery for possible predictions of Global Conveyor.