Variability of deep water mass characteristics in the North Aegean Sea: The role of lateral inputs and atmospheric conditions

Abstract

The North Aegean Sea is considered as one of the major dense water formation sites of the Eastern Mediterranean Sea, contributing to the renewal of the Mediterranean deep water masses. We investigate the variability of the deeper water mass characteristics during the period 2002–2008, employing the Hybrid Coordinate Ocean Model for the North Aegean region. Two significant dense water formation events were detected, and the role of the major lateral water inputs, namely waters of Levantine Sea and Black Sea origin, was investigated. Atmospheric conditions were identified as the main factor of dense water formation during 2003, when strong buoyancy loss due to the low winter temperatures produced new dense water masses in the surface and intermediate layers (<400m). During 2006, it was the intrusion of more saline Levantine waters that increased the sigma–theta of the south North Aegean region, creating idealized conditions for a potential greater dense water formation event. The Black Sea Waters spreading may affect the Mixed Layer Depth variability, promoting the stratification of the water column and playing a vital role on the dense water formation activity, working against the open-sea convection of denser waters.