Numerical Modelling of Dust Propagation in the Atmosphere of Tbilisi City: The Case of Background Eastern Gentle Breeze

Abstract

Dust propagation at the territory of Tbilisi is studied using the 3D regional model of atmospheric processes evolution and integration of the equation of contaminant transfer-diffusion. The dust pollution process that takes place in case of background eastern gentle breeze is numerically modeled. It is obtained that micro-scale dust propagation substantially depends on the terrain of city and its surrounding territories, on the magnitude and direction of background wind velocity. Dust dispersed in Tbilisi is mainly concentrated in the lower 600 m thick atmospheric boundary layer. At 2 m height over a ground maximum concentration 1.0-1.5 maximum allowable concentration (MAC = 0.5 mg/m³)is formed in the time interval from 12 a.m. to 9 p.m. in the central and southern parts of the city as well as at relatively low-lying territories. Peculiarities of dust vertical distribution and time variation are studied.