Urban surface temperature observations from ground-based thermography: intra- and inter-facet variability

Ground based thermal cameras are used to observe urban surface temperatures (Ts) with an unprecedented combination of: temporal and spatial resolution (5 min ~0.5 m ? 2.5 m), extent (3.9 ha), instrument number (6 static cameras) heterogeneity (mixed high rise vegetation). Unsupervised classification of images by geometry material properties (surface orientation, albedo, solar irradiance, shadow history) is facilitated a detailed three-dimensional model (430 x 430 extent) sensor view modelling. From source area analysis, 9.5 % the observed cameras. Across all camera pixels, 5th - 95th percentile Ts differences reach 37.5 K around midday. Roofs have greatest diurnal range (290.6 329.0 K). across sunlit sloped roofs 23.3 K. Walls different cardinal orientations consistently differ > 10 between 10:00 15:00. Shadow tracking within cooling rates, where recently shaded (< 30 min) ground can be 18.6 warmer than equivalent unshaded Ts. West walls remain warm past sunset 1.2 north at 23:00 (~4 hours after sunset). Recently cool exponentially ambient similar rate as ground, but four times slower roofs. The characteristics anticipated wide applications (e.g. evaluation energy balance models, ground-truthing satellite remote sensing).