Complete Urban Surface Temperatures

TLDR

The study presents two methods to estimate the complete urban surface temperature. An observation program using ground and airborne thermal infrared radiometers, together with the two proposed methods, estimates the complete urban surface temperature by accounting for total active surface area. The complete urban surface temperature, defined by the authors, differs from nadir and off‑nadir airborne estimates, aligns with off‑nadir measurements of shaded walls, and shows significant differences across land‑use types in Vancouver, with implications for air temperature estimation and sensible heat flux.

Abstract

An observation program using ground and airborne thermal infrared radiometers is used to estimate the surface temperature of urban areas, taking into account the total active surface area. The authors call this the complete urban surface temperature. This temperature is not restricted by the viewing biases inherent in remote sensors used to estimate surface temperature over rough surfaces such as cities. Two methods to estimate the complete surface temperature are presented. Results for three different land-use areas in the city of Vancouver, British Columbia, Canada, show significant differences exist between the complete, nadir, and off-nadir airborne estimates of urban surface temperature during daytime. For the sites and times studied, the complete surface temperature is shown to agree with airborne off-nadir estimates of the apparent surface temperature of the most shaded walls. Some implications of using the complete surface temperature to estimate screen level air temperature and to calculate surface sensible heat flux are given.