Simulating air temperature in an urban street canyon in all weather conditions using measured data at a reference meteorological station

Abstract

A model is proposed that adapts data from a standard meteorological station to provide realistic site-specific air temperature in a city street exposed to the same meso-scale environment. In addition to a rudimentary description of the two sites, the canyon air temperature (CAT) model requires only inputs measured at standard weather stations; yet it is capable of accurately predicting the evolution of air temperature in all weather conditions for extended periods. It simulates the effect of urban geometry on radiant exchange; the effect of moisture availability on latent heat flux; energy stored in the ground and in building surfaces; air flow in the street based on wind above roof height; and the sensible heat flux from individual surfaces and from the street canyon as a whole. The CAT model has been tested on field data measured in a monitoring program carried out in Adelaide, Australia, in 2000Australia, in -2001. After calibrating the model, predicted air temperature correlated well with measured data in all weather conditions over extended periods. The experimental validation provides additional evidence in support of a number of parameterisation schemes incorporated in the model to account for sensible heat and storage flux.

Intra‐urban differences in canopy layer air temperature at a mid‐latitude city

“…Meteorological records used in this analysis were made on the basis of measurements carried out at two adjacent urban street canyons, at an open site about 1.6 km to the northeast in the belt of parklands surrounding central Adelaide, and at the Australian BoM weather station at the suburb of Kent Town, about 1.7 km to the east (Erell and Williamson, 2006). Their locations are shown in Figure 2.…”

“…NTC thermistors (MEA model 6507, nominal accuracy 0.2°C) were housed in radiation shields constructed especially for the experiment (Erell and Williamson, 2006). Comparative tests of this type of makeshift instrument shield in conditions of very bright sunlight and low wind against a mechanically aspirated standard, confirmed that it was superior to the conventional Stevenson screen (Erell et al, 2005), which has been shown to produce some error in such conditions (World-Meteorological-Organization, 1971;Sparks, 1972;Andersson and Mathisson, 1992;van der Meulen, 1998).…”

“…The measured differences in air temperature between the two streets could also be replicated in the Canyon Air Temperature (CAT) model (Erell and Williamson, 2006), which adapts data from a standard meteorological station to provide realistic site-specific air temperature in a city street exposed to the same mesoscale environment. In addition to providing further evidence for the validity of the CAT model itself, this result demonstrates that the effects of street orientation, although small, can be estimated by quantitative modeling of the surface energy balance.…”

“…Several such experiments have been carried out in recent years, such as the Athens urban climate experiment (Santamouris, 1998;Livada et al, 2002), extended heat island measurements in Göteborg (Eliasson, 1996a) and extensive studies of Vancouver (Runnalls and Oke, 2000) and Singapore (Chow and Roth, 2006). This paper presents the results of a monitoring study carried out in the city of Adelaide, Australia, where the primary aim was to calibrate a model capable of predicting air temperature in an urban street canyon for extended periods in a variety of weather conditions on the basis of meteorological time series recorded at an open site exposed to the same mesoscale conditions (Erell and Williamson, 2006). Various meteorological parameters were recorded continuously over the course of nearly a year at two urban street canyons in the dense core of the city and at an open reference site.…”

The influence of trees and grass on outdoor thermal comfort in a hot‐arid environment

“…It has been observed repeatedly that due to the dominance of radiation in hot-arid settings, air temperature alone is not necessarily a robust indicator of overall thermal comfort for pedestrians in the urban space (Ali-Toudert and Mayer, 2006;Johansson, 2006;Pearlmutter et al, 2006). Thus, the actual microscale effects of urban vegetation on human comfort are complex and interrelated with the effects of other built elements in the city, whose geometry and surface properties may vary widely (Stabler et al, 2005;Shashua-Bar et al, 2006;Erell and Williamson, 2006). One implication of this complexity is that some UHI mitigation strategies, such as the use of high-albedo surfaces (e.g.…”