Relationship of land surface and air temperatures and its implications for quantifying urban heat island indicators-An application for the city of Leipzig (Germany)

Urban heat islands (UHIs) describe the phenomenon of altered temperatures that occur in urban areas when compared to their rural surroundings. UHIs influence human well-being, human health and the city as an ecological niche. UHIs can be quantified with meteorological ground measurements of air temperatures or with remotely sensed land surface temperatures (surface urban heat island). Both approaches have advantages and disadvantages and are rarely combined. Further, within these approaches, different indicators for quantifying the UHIs are used. In this methodological study, we (1) combined data on land surface and air temperatures, (2) enriched the debate by suggesting the application of indicators for the two distinct data sets and (3) systematically quantified indicators of all approaches for the city of Leipzig, Germany. A relationship between the land surface and air temperatures was established. However, the results for the single indicators showed that the absolute values of the detected UHI in Leipzig depend on the selected indicator and the data set used. The main conclusion for future studies on UHIs is to use several UHI indicators in parallel to acknowledge the uncertainty of measuring the UHI using a single indicator and either ground measurements or remote sensing. (C) 2012 Elsevier Ltd. All rights reserved.