WRF/UCM model was used to simulate the meteorological characteristics of an air pollution episode over the Pearl River Delta (PRD) in autumn

2008. In order to study the impact of urbanization on atmospheric boundary layer characteristics

this article set up sensitivity experiments by changing the surface landuse type and the anthropogenic heat flux. The results showed that urbanization

including the increase of urban area

anthropogenic heat and the increase of its flux

helped to strengthen the effect of urban heat island and urban dry island

and the surface temperature inversion turned to be more obvious

which resulted in the accumulation of surface pollutants. Urbanization not only decreased the wind speed due to the increase of surface roughness

but also strengthened the heat island circulation

which was adverse to the diffusion of pollutants and caused the pollution episodes in urban areas. Moreover

the urbanization could raise the atmospheric boundary layer height both in daytime and nighttime.