Image Representations of Complete Urban Surface Temperatures

Urban areas are characterized by a strongly three‐dimensional structure in which vertical surfaces can comprise a significant component of the total surface area. Two‐dimensional images of radiometric surface temperature obtained from remote sensors suffer from anisotropy and may provide biased representations of the actual complete urban surface temperature. In this paper, directional radiometric surface temperatures and a GIS of building shapes are combined to generate two‐dimensional images of urban surface temperature that include three‐dimensional temperature information. The method provides flexibility in accessing and combining temperatures of major surface components for studies that seek to understand the relationship between surface temperature and the behaviour of the near‐surface atmosphere in urban areas. The influence of building walls reduced the nadir temperatures by over 4 K in daytime and increased them by up to 1 K at night. Spatial patterns of complete surface temperature are similar to nadir temperatures in this study area, but there are several contributing factors. At the scale of individual buildings in daytime, inclusion of wall temperatures has a larger effect on the calculated building temperature than does the typical effect of surface emissivity.