Mesoscale numerical modeling of the boundary layer of the atmosphere adapted to the Northwestern Black Sea region. Part 2. Finite-difference solution and adaptation to real physical and geographical conditions of the area

Abstract

The article describes the finite-difference solution of the system of differential equations of the atmospheric boundary layer hydrothermodynamics adapted to the Northwestern Black Sea region. The research presents the description of the sequence of calculations schematically shown on the flowchart. The applied mathematical model was adapted in relation to five aspects: coast geomorphology (coastline shape), land geomorphology (actual terrain of the studied territory), thermal and physical characteristics of soil (density, specific gravity, porosity, thermal conductivity factor), roughness (roughness parameter) and optical characteristics (albedo) of the underlying surface. The coastline shape was described with consideration of water proportion available in the current cell of the spatial grid. If the proportion exceeded 50 %, it was assumed that such cell includes land, and vice versa. The terrain matrix was formed by removing the elevation values at each point of the calculated area from official electronic elevation maps. The thermal and physical characteristics of the soil were set depending on a type of soil observed at the current calculated point. The method of roughness elements double recording during growing and non-growing periods of the year was used to consider the roughness of the underlying surface. This method consists in the fact that, depending on the agricultural zoning and its subject content, there is a certain background weighted average value of roughness elements ensemble elevation that transforms into a roughness parameter through the proportionality factor. In such a case, the proportionality factor is linked to a type of a real roughness element at a specific point. Thus, a comprehensive assessment of roughness features of the territory under study was obtained. The albedo of the underlying surface was taken for three various periods of the year: growing period (April-September), post-growing period – months before winter and the first month of spring (October-November, March) and winter period (December-February). Nature of the external coating of the underlying surface related to optical properties should be also taken into account.