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

Abstract

In this work, density inversions in the Greenland Sea, which precede a 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 jet intrusions of warm Atlantic Water and cold water from the East Greenland Current was identified, the role of ocean-atmosphere heat flux and the freshwater balance of the sea surface were determined over two time periods: the 1990s (1993, 1994, 1998) and the 2010s (2008, 2011, 2013). The following main mechanisms of formation of the density inversions were identified: The ocean-atmosphere heat flux, jet intrusions of the upper ocean water, and difference between evaporation and precipitation. The density inversions are often formed by a combination of these mechanisms. The ocean-atmosphere heat flux is the main source of inversions observed with 93 % of the profiles with inversions. In the 1990s, jet intrusions of ocean water formed the second most important factor, with the difference evaporation-precipitation being the third one. In the 2010s, however, the third factor became more important than the second one, as evaporation started dominating significantly over precipitation. An increase of a contribution of the latter factor occured together with an increase in the number of salinity inversions during the 2010s compared to the 1990s and was a result of a change in the dominating winds over the region. These results form a basis for further investigation of the mechanisms of interannual variability of deep convection in the Greenland Sea.