Numerical study of pollutants dispersion in urban atmosphere in warm and cold seasons (Krasnoyarsk city as an example)

The results of simulation scenarios of passive impurities transport in the city of Krasnoyarsk during the warm and cold periods are presented. The calculations are based on a mesoscale non-hydrostatic model. The purpose of the ongoing research is to study the characteristics of the formation of mesoclimates in Krasnoyarsk, a description of the characteristic meteorological conditions and an assessment of their impact on the accumulation of impurities in the urban atmosphere. We concentrate on meteorological scenarios with weak winds, since such conditions are most unfavorable from the point of view of the accumulation of impurities in the lower atmosphere. Under these conditions, we compare scenarios of the distribution of impurities from high sources. Numerical experiments with the parameters we chose showed that there was no significant effect of high sources of impurities on the accumulation of pollution in the surface layer, both in the conditions of winter surface inversions and in summer conditions. The differences are in the level of concentrations and their localization: in winter, the concentrations are higher and the areas of distribution are smaller, while in summer, the areas are larger and the concentrations are smaller. In summer, in contrast to the winter, diurnal variability is more pronounced. The daily rotation of the plumes is due to the formation of local circulations like mountain-valley type.