The Urban Heat Island (UHI) field campaign was conducted on the 4th-5th April 2008 in Phoenix, Arizona. Inter alia, infrared thermography (IRT) was used for UHI mapping. The focus was on downtown Phoenix, characterized by the presence of several high-rising, densely packed buildings of different façade materials ranging from glass to concrete. The aim was to investigate UHI modifications within the city of Phoenix at three spatial scales i.e. the local (Central Business District, CBD), the neighborhood and the city scales. This was achieved by combining IRT measurements taken at ground level by mobile equipment (automobile-mounted and pedicab) and at high elevation by a helicopter.

The overall experimental set-up, general methodology and meteorological aspects will be discussed in companion papers. Here we address the influence of local features on air temperature and wind flow patterns at the CBD and neighborhood scales. The equipment (“pedicab”) used for local scale measurements allowed us to collect detailed thermographic images of about twenty building façades and several street canyons. In total, about two thousand images were taken during the 24-hour campaign. Images were taken at regular intervals of two hours throughout the day starting from 6 LST. Image analysis provides detailed information on building surface and pavement temperatures at fine resolution. This unique dataset allows us several investigations on local air temperature dependence on albedo, building thermal inertia, building shape and orientation and sky view factors. Besides, the mosaic of building façade temperatures are being analyzed in terms of local buoyancy fluxes and possible wind flow modifications by such thermally driven flows will be elucidated.

The results are of consequence for understanding of microclimate of cities and planning of heat mitigation measures.