Mechanisms for the formation of density inversions in areas of regular deep convection in the Greenland Sea

Abstract

In this work, density inversions in the Greenland Sea, which precede the development of deep convection, were identified from in-situ data. The mechanisms of their formation were considered, for which data from the GLORYS12V1 ocean reanalysis and the ERA5 atmospheric reanalysis were used. In particular, the surface inflow of warm Atlantic water and cold water from the East Greenland Current was identified, the role of heat transport from the ocean to the atmosphere and the freshwater balance of the sea surface for two periods: the 1990s (1993, 1994, 1998) and the 2010s (2008, 2011, 2013) was determined. The following main mechanisms of density inversions formation were identified: heat transport from the ocean to the atmosphere, surface water inflows, and positive evaporation-precipitation differences. The formation of density inversions can also be determined by a combination of different mechanisms. Heat fluxes from the ocean to the atmosphere are the main source of inversions and are observed for 93% of all profiles with inversions. In the 1990s, surface water fluxes were the second most important factor, with evaporation- precipitation differences being the third. In the 2010s, however, the last two factors are reversed and evaporation dominates significantly more than precipitation. Increase of contribution of this factor occurs together with increase of number of salinity inversions in 2010th in comparison with 1990th and is connected with variability of dominating winds in this region. The results provide a basis for further investigation of the causes and interannual variability of deep convection in the Greenland Sea.