An urban canopy-layer climate model

Abstract

This paper outlines a computer simulation model designed to assess the thermal characteristics of the urban canopy layer (UCL). In contrast to other UCL models, the layer simulated here includes both closed volumes (buildings) and open volumes (canyons). The purpose of the model is to allow the comparison of the climate impacts of different building group configurations. Traditional boundary-layer theory is applied to the surface urban boundary layer (UBL) which lies above the UCL and the derived relations are used to parameterize exchanges of momentum and heat across the UBL/UCL interface. The exterior energy budgets of the roof, walls and floor of the canopy are solved using an equilibrium surface temperature method. The open canopy and interior building air temperatures are found which are in agreement with the surface exchanges. Using measured data for Los Angeles in June, the output of the model is examined. The results show some agreement with measurement studies and suggest that the density of structures can have a substantial impact on UCL/UBL interaction.