Urban Effects on the Convective Boundary Layer

Abstract

The influence of an urban area on the turbulent convective boundary layer is studied using an instrumented aircraft. Data from three undisturbed days with low wind speeds are presented to describe the urban effects on turbulent profiles of heat, moisture, momentum and turbulent intensity. The profiles in the urban Area are observed to be considerably different than the rural. The urban area substantially enhances the surface heat flux, hence the vertical component of turbulence. The enhanced urban vertical turbulent intensifies extend through the urban boundary layer, resulting in stronger entrainment through the urban inversion than the rural. This, in turn, results in enhanced vertical fluxes of temperature, moisture and stress at the urban inversion. The effects of the urban roughness on boundary-layer structure are observed to be small in comparison with the effects of urban heating for the light wind cases studied.