Thermal Changes Induced by Urbanization and Pollutants

Abstract

A numerical model of the planetary boundary layer, based on the Eulerian conservation equation, is used for two- and three-dimensional simulations of wind, temperature, specific humidity and pollutant concentration within the boundary layer surrounding urban areas. The variations of the terrain are included in the simulations. Two- and three-dimensional simulations of the thermal structure and pollutant concentrations are highly correlated. The simulated urban heat island and vertical thermal structure compare realistically with observations. The temperature changes caused by radiatively active pollutants are generally smaller than effects induced by other urbanization factors. During daytime, the presence of radiatively active pollutants resulted in increased vertical stability and higher concentrations near the surface when compared with radiatively inactive pollutants.