Urbanization and Pollutant Effects on the Thermal Structure in Four Climatic Regimes

Abstract

A numerical model based on the Eulerian conservation equation simulated the urban heat island in tropical, desert, mid-latitude and tundra climatic regimes in a two-dimensional mode. Data are based on typical climatological descriptions. Experiments to identify the effects of individual urbanization characteristics showed anthropogenic heating to be important in the mid-latitudes and tundra, and that radiative effects of pollutant aerosols are minimal except in the tundra. Four types of urban heat islands, over a day's duration, both negative and positive, are possible in various climatic regimes and seasons. Simulations showed that a positive heat island forms in the urban arm in the absence of sun, and negative heat islands are formed as the daylight lengthens. The largest urban thermal effects occurred in the tundra regions and relatively small effects occurred in the tropics and deserts.