Deep water distribution and transport in the Nordic seas from climatological hydrological data

Abstract

Deep water in the Nordic seas is the major source of Atlantic deep water and its formation and transport play an important role in the heat and mass exchange between polar and the North Atlantic. A monthly hydrological climatology—Hydrobase II—is used to estimate the deep ocean circulation pattern and the deep water distribution in the Nordic seas. An improved P-vector method is applied in the geostrophic current calculation which introduces sea surface height gradient to solve the issue that a residual barotropic flow cannot be recognized by traditional method in regions where motionless level does not exist. The volume proportions, spatial distributions and seasonal variations of major water masses are examined and a comparison with other hydrological dataset is carried out. The variations and transports of deep water are investigated based on estimated circulation and water mass distributions. The seasonal variation of deep water volume in the Greenland Basin is around 22×103 km3 whereas significantly weaker in the Lofoten and Norwegian Basins. Annual downstream transports of about 1.54×103 and 0.64×103 km3 are reported between the Greenland/Lofoten and Lofoten/Norwegian Basins. The deep water transport among major basins is generally in the Greenland-Lofoten-Norwegian direction.