Numerical studies of urban planetary boundary-layer structure under realistic synoptic conditions

Abstract

The control simulations of the temperature, boundary layer depth, specific humidity and wind fields exhibited essentially the same behavior as observed in the urban PBL throughout the morning forecast period. Unlike many other documented cases that displayed strong urban-induced low-level convergence, the confluence on this morning was relatively weak, with the center of the heat island displaced (in both the simulation and the observations) downwind (south) of the city. A relative minimum in windspeed was associated with the center of the displaced heat island. The sensitivity experiments clearly demonstrated that reduction of surface evaporation due to urbanization was the most important factor contributing to the development and maintenance of the urban PBL perturbation. -from Authors