Radiative Effects of Elevated Pollutant Layers on Temperature Structure and Dispersion in an Urban Atmosphere

Abstract

An unsteady two-dimensional transport model has been used to study the short-term effects of elevated pollutant layers on the temperature structure and pollutant dispersion in an urban planetary boundary layer. The effects of radiatively interacting pollutants on radiative transfer have been accounted for and the variation of the physical properties of the soil, the radiation characteristics of the earth's surface, and the urban heat and pollutant emissions along the city were included. The results of the numerical experiments performed with the model showed that the aerosol-induced heating during daylight hours increases the temperature, while the cooling associated with gaseous pollutants decreases the temperature during the night in the elevated pollutant layer. The net effect of air pollution was to hinder the mixed-layer growth during the day. The results obtained show that the maximum impact of air pollution on the urban PBL is on the evolution of temperature and pollutant concentration profiles and is in agreement with the results of previous investigators.