The Interaction Between Nocturnal Urban Atmospheric Boundary Layer and Aerosols

Combining with the surface heat balance equation, a nonlinear and unsteady two-dimensional numerical model, which is closed by energy method, has been used to study the interaction between nocturnal urban bounday layer and aerosols. The results show that the effect of aerosols are to warm up the low boundary layer and cool down the upper boundary layer at night; aerosols decrease the stability of low boundary layer and increase the stability of upper boundary layer. In addition, aerosols can decrease the intensity of inversion close to ground. In the city polluted normally by aerosols, the influence of aerosols on the intensity of urban heat island isn’t large, but they can increase slightly urban heat island circulation. The feedback effect of nocturnal urban boundary layer on aerosols is to decrease aerosol concentrations in the low boundary layer and increase in the upper. Part of the above conclusions are verified by the observational data on urban heat island in Tianjin city