Numerical study of the circulation and its contribution to the oil slick transport in the southeastern part of the Black Sea

Abstract

The relevance of studying and forecasting regional circulation and the spread of impurities in the shelf/coastal zones of the seas is determined by intensive human economic activity, which causes a large anthropogenic load on coastal marine ecosystems. The aim of this paper is to study the mesoscale circulation under real atmospheric forcing and its contribution to the oil slick transport in the southeastern part of the Black Sea using a regional model of the Black Sea dynamics (RM-IG) and a 2-D oil slick transport model, which is coupled to the RM-IG. The RM-IG with 1 km horizontal resolution is based on a z-level primitive equations system of ocean hydrothermodynamics. During the EC project ARENA (2003–2005) the RM-IG was nested in the basin-scale model of the Black Sea dynamics of Marine Hydrophysical Institute (Sevastopol, Ukraine) with 5 km horizontal resolution. The transport model is based on 2-D advection-diffusion equation for non-conservative substances. Atmospheric forcing is taken into account by prognostic meteorological fields derived from the atmospheric model SKIRON. Numerical experiments have shown that during all seasons there is a generation, deformation, and disappearance of anticyclonic and cyclonic meso- and submesoscale vortex formations, which have a significant impact on the pollutants dispersion process. Intensive vortex formations are observed during light winds. Strong winds have a smoothing effect and prevent the formation of vortex structures. In a number of cases, the unstable eddy formations with a diameter of 5–20 km are generated in a narrow strip along the Georgian coast presenting a width of about 20–30 km.