"At the modern stage of the development of Geosciences, the study of hydrothermodynamic and ecological processes occurring in the natural environment (sea, atmosphere, soil), their monitoring and forecasting become very relevant and are a necessary condition for sustainable development of society. The Caucasus region is one of the most difficult regions of the world from the point of view its physical and geographical features. These features include the Black and Caspian Seas and the complex terrain of the Caucasus. The Seas and the atmosphere are unified hydrodynamic systems, between subsystems of which processes of an exchange of energies, momentum and substances continuously take place. One of the most effective ways to study natural and environmental processes is methods of mathematical modeling, which allows reproducing these processes and phenomena and studying the quantitative contribution of various factors to the development of such processes. The purpose of the paper is to discuss the models of the Black Sea and atmospheric dynamics developed at M. Nodia Institute of Geophysics of I. Javakhishvili Tbilisi State University, and some results of their implementation. The model of the Black Sea dynamics is based on a full system of ocean hydro-thermodynamics equations. Its high-resolution version, which is nested in the basin-scale model of the Black Sea dynamics of Marine Hydrophysical Institute (MHI, Sevastopol), is used to forecast main hydrophysical fields for the easternmost part of the Black Sea. The model of the atmospheric dynamics is based on a full system of atmospheric hydro-thermodynamics equations in hydrostatic approximation written in the terrain-following coordinate system and is realized for the extended territory including the eastern part of the Mediterranean Sea and Black and Caspian seas and for the Caucasus region. These models, after some modification will form the basis of the coupled Black Sea-atmosphere limited-area modeling system."

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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.

Micro-scale processes of dust distribution in the city of Tbilisi with very complex topography are modeled using a 3D regional model of atmospheric processes and numerical integration of the transport-diffusion equation of the impurity. The Terrain-following coordinate system is used to take into account the influence of a very complex relief on the process of atmospheric pollution. Modeling is carried out using horizontal grid steps of 300 m and 400 m along latitude and longitude, respectively. Cases of the stationary background eastern light air are considered. In the model, motor transport is considered as a nonstationary source of pollution from which dust is emitted into the atmosphere. Modeling of dust micro-scale diffusion process showed that the city air pollution depends on the spatial distribution of the main sources of city pollution, i.e. on vehicle traffic intensity, as well as on the spa

Microscale processes of dust distribution in the city of Tbilisi with a very complex topography are modeled using a 3D regional model of atmospheric processes and numerical integration of the transport-diffusion equation of the impurity. The Terrain-following coordinate system is used to take into account the influence of a very complex relief on the process of atmospheric pollution. Modeling is carried out using horizontal grid steps of 300 m and 400 m along latitude and longitude, respectively. The cases of the stationary background eastern and western weak winds are considered. In the model, motor transport is considered as a nonstationary source of pollution from which dust is emitted into the atmosphere. Modelling of dust micro-scale diffusion process showed that the city air pollution depends on spatial distribution of the main sources of city pollution, i.e. on vehicle traffic intensity, as well as on spatial distribution of highways, and micro-orography of city and surrounding territories. It is shown that the dust pollution level in the surface layer of the atmosphere is minimal at 6 a.m. Ground-level concentration rapidly grows with increase of vehicle traffic intensity and by 12 a.m. reaches maximum allowable concentration (MAC = 0.5 mg/m3) in the vicinity of central city mains. From 12 a.m. to 9 p.m. maximum dust concentration values are within the limits of 0.9-1.2 MAC. In the mentioned time interval formation of the highly dusty zones, and slow growth of their areas and value of ground-level concentrations take place. These zones are located in both central and peripheral parts of the city. Their disposition and area sizes depend on spatial distribution of local wind generated under action of complex terrain, as well as on the processes of turbulent and advective dust transfer. From 9 to 12 p.m. reduction of dust pollution and ground-level concentration takes place. After the midnight city dust pollution process continues quasi-periodically. As result of the analysis of vertical distribution of dust concentration is obtained that a basic dust mass emitted into the atmosphere is located in the 100 m surface layer. Concentration value in the upper part of this layer reaches 0.8 MAC and rapidly decreases with altitude increase.