Connectivity of North Aegean circulation to the Black Sea water budget

Abstract

The brackish Black Sea Waters (BSW) outflow to the Aegean Sea, through the Dardanelles Strait, affects and determines significantly the physical characteristics of the North Aegean Sea. Continuous monitoring of the Dardanelles outflow physical properties does not exist. Here, we present the development of a novel methodology to extract a 2-year (2002–2003) timeseries of the transport rates and physical characteristics of the exchange at Dardanelles Strait. Specifically, we have developed a two-layer Dardanelles flow mathematical parameterization, based on the Black Sea water budget, in order to calculate the buoyant outflow characteristics. This was applied as time varying input to the high resolution (1/50°), three-dimensional, North Aegean HYCOM model with realistic forcing conditions (boundary, initial, atmospheric). The simulation results revealed a strong correlation between the BSW spreading and the formation of major North Aegean hydrodynamic circulation patterns. The distribution of several physical (salinity, temperature, mixed layer depth) and biological (chlorophyll-a) characteristics, exhibits an intensive horizontal variability, which depends on the combination of four North Aegean factors: the BSW pathways, the meteorological conditions, the major rivers outflow and the mass exchanges with the South Aegean. Validation of the new parameterization approach showed higher correlation between model results and satellite and in situ data, in comparison to previous parameterizations that employed climatogically varying inputs at the Dardanelles. The novel methodology allows, for the first time, the connectivity of the Aegean Sea circulation to the Black Sea water budget through the Dardanelles Strait.