Response of the urban boundary layer to heat addition and surface roughness

A two-dimensional numerical model is used to determine the sensitivity of the urban climate of mid-latitude cities to heat addition and surface roughness. Nocturnal winter conditions are considered. Artificial heating is found to be the major factor in controlling the urban temperature field, and roughness the controlling factor for the wind field. Present rates of heat addition are found to warm the urban air by 2 to 4K. Results from the model are compared with observational data for Montreal. The effects of varying the heights of heat addition and the use of greenbelts are also examined.