SIMULATION OF THE ENERGY BUDGET OF AN URBAN CANYON .2. COMPARISON OF MODEL RESULTS WITH MEASUREMENTS

A simple numerical model that attempts to simulate the energy budget o f an urban canyon is assessed by comparing its predictions against mea surements made at an urban field site. A street is chosen that satisfi es many of the model's requirements and a measurement scheme is devise d to measure variables which are also simulated. The model is run usin g input information collected from the field and the data produced are compared with the measured data. The results indicate that the model is capable of simulating many of the climate attributes (such as surfa ce temperatures and net radiation at the canyon top) accurately, but d oes not simulate the dominant mechanism of sensible heat exchange betw een the canyon environment. Nevertheless, the model predicts a small a nd largely invariant exchange, similar to that measured. The results t he field study, When compared with other published work, indicates tha t as street canyons become narrower they become increasingly isolated in terms of heat exchange from the overlying atmosphere. The results o f the computer runs appear to follow this pattern.