A NUMERICAL STUDY OF THE EFFECT OF URBAN GEOMETRY UPON THE SURFACE-ENERGY BUDGET

This numerical study investigates the effect of urban canyon geometry upon the thermal environment using a parking lot model and an urban ca nyon model in identical meteorological conditions. The urban canyon mo del assumes two buildings on opposite sides of a street, no windows or interior anthropogenic heat source, an infinitely long east-west orie nted canyon, and waterproof surfaces. The simulated surface temperatur es agree well with those obtained by field measurement. The energy bal ance of the urban canyon is represented by that of the canyon top, whi ch is an imaginary surface. The urban canyon, whose top surface is a p lane above the canyon at the same level as the roof surface of the bud ding absorbs more heat in the daytime and releases more at night than the parking lot. The urban thermal environment depends on an urban geo metry which particular to the urban canyon model produces reduced smal l sky view factors and complicated daytime shadow patterns. The result s show that this urban geometry contributes to urban heat island forma tion.