Characteristics of Density Inversions in the Greenland Sea during the Cold Seasons in 1993–2019

Abstract

Purpose. The study aims at revealing spatial and temporal variability of the characteristics of density inversions in the Greenland Sea and at proposing the mechanisms of their formation during the cold seasons in 1993–2019. This helps further understanding the mechanisms which govern variation in the convection intensity in the sea. Methods and Results. The in-situ temperature and salinity taken from the EN.4.2.1 dataset (Met Office Hadley Center Database) and casted during the cold season (November – April), are used in the study. The vertical profiles reveal a number of potential density inversions. The biggest vertical scale of a winter-mean inversion reached about 400 m and was recorded in the years of maximum convection intensity (2008, 2011 and 2013), and the largest value of density gradients were observed in the 1990s when convection was less intensive. Predominantly haline destabilization prevailed (about 70% of all the profiles with inversions) throughout the region; it was observed especially often in the northeastern part of the area under study. Exclusively haline destabilization accounts for 40% of all the profiles, exclusively thermal one – 13%, as for the rest of the profiles, both haline and thermal destabilizations are detected. In the 2010s, salinity contribution to the formation of inversions exceeds the one that had been observed in the mid-1990s. Conclusions. The in-situ data confirm the leading role of winter salinity increase in formation of the water density inversions in the upper ocean, and, consequently, in the development of deep convection. This may indicate a significant role of potential instability in the development of convection in the region.

Keywords

• convection
• atlantic ocean
• greenland sea
• deep convection
• density inversions
• potential instability