Ventilation of the Upper Labrador Sea Water, 2003-2005

In 2003 and in 2005, hydrographic data provided sufficient spatial coverage in the Labrador Sea to infer basin wide changes in the water mass characteristic of the Upper Labrador Sea Water (ULSW). The ULSW was considerably saltier and warmer in 2005 than in 2003. Although convection in the Labrador Sea leads to mixing with salinity-poor surface water and is opposed to the observed salinity trend, the increased vertical homogeneity of the CTD profiles, the increase in the ULSW thickness and the intensification of the potential vorticity minimum for the isopycnals sigma(Theta) = 27.700 - 27.734 kg/m(3) in 2005 point to convection in winter 2005 which ventilated at least about 20% of the Labrador Sea region.