Modeling the buoyancy-driven Black Sea Water outflow into the North Aegean Sea

A three-dimensional numerical model was applied to simulate the Black Sea Water (BSW) outflux and spreading over the North Aegean Sea, and its impact on circulation and stratification–mixing dynamics. Model results were validated against satellite-derived sea surface temperature and in-situ temperature and salinity profiles. Further, the model results were post-processed in terms of the potential energy anomaly, ϕ, analyzing the factors contributing to its change. It occurs that BSW contributes significantly on the Thracian Sea water column stratification, but its signal reduces in the rest of the North Aegean Sea. The BSW buoyancy flux contributed to the change of ϕ in the Thracian Sea by 1.23 × 10-3 W m-3 in the winter and 7.9 × 10-4 W m-3 in the summer, significantly higher than the corresponding solar heat flux contribution (1.41 × 10-5 W m-3 and 7.4 × 10-5 W m-3, respectively). Quantification of the ϕ-advective term crossing the north-western BSW branch (to the north of Lemnos Island), depicted a strong non-linear relation to the relative vorticity of Samothraki Anticyclone. Similar analysis for the south-western branch illustrated a relationship between the ϕ-advective term sign and the relative vorticity in the Sporades system. The ϕ-mixing term increases its significance under strong winds (> 15 m s-1), tending to destroy surface meso-scale eddies.