Simple Model for Spatially-averaged Wind Profiles Within and Above an Urban Canopy

• Published in: Boundary-layer meteorology Vol. 127; no. 1; pp. 131 - 151
• Main Authors: Di Sabatino, S, Solazzo, E, Paradisi, P, Britter, R
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01-04-2008; Springer Netherlands; Springer; Springer Nature B.V
• Subjects: Atmospheric boundary layer; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Buildings; Canopies; Convection, turbulence, diffusion. Boundary layer structure and dynamics; Digital elevation model; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Exact sciences and technology; External geophysics; Geophysics. Techniques, methods, instrumentation and models; Meteorology; Morphological parameters; Morphology; Neighbourhood scale; Original Paper; Shear stress; Spatially-averaged wind profiles; Urban areas; Urban canopy; Wind; Wind tunnels; Digital elevation model; Neighbourhood scale; Spatially-averaged wind profiles; Morphological parameters; Urban canopy; models; Aerodynamic drag; Wind field; Urban structure; urban areas; troposphere; shear stress; parametrization; algorithm performance; Atmospheric boundary layer; Vertical profile; flow field
• ISSN: 0006-8314; 1573-1472
• DOI: 10.1007/s10546-007-9250-1

This paper deals with the modelling of the flow in the urban canopy layer. It critically reviews a well-known formula for the spatially-averaged wind profile, originally proposed by Cionco in 1965, and provides a new interpretation for it. This opens up a number of new applications for modelling mean wind flow over the neighbourhood scale. The model is based on a balance equation between the obstacle drag force and the local shear stress as proposed by Cionco for a vegetative canopy. The buildings within the canopy are represented as a canopy element drag formulated in terms of morphological parameters such as λ f and λ p (the ratios of plan area and frontal area of buildings to the lot area). These parameters can be obtained from the analysis of urban digital elevation models. The shear stress is parameterised using a mixing length approach. Spatially-averaged velocity profiles for different values of building packing density corresponding to different flow regimes are obtained and analysed. The computed solutions are compared with published data from wind-tunnel and water-tunnel experiments over arrays of cubes. The model is used to estimate the spatially-averaged velocity profile within and above neighbourhood areas of real cities by using vertical profiles of λ f .