Thermal Remote Sensing at Urban Scale: applications and a case study

One of the most crucial aspects in urban management is constituted today by the energy aspects: reducing consumption and CO2 emissions is a primary objective to be pursued for a sustainable development. In this direction an accurate knowledge of consumptions and waste due to heating of single houses, blocks or districts is needed. A synoptic information can be acquired only by flights through sensors operating in the thermal band, either on airplanes or satellite platforms. At a different scale and with different problems, another major research subject is the Urban Heat Island, which is related not only to sensible heat released by anthropic activities, but also to land use variations and evapotranspiration reduction. The development and deploying of new sensors can therefore open new perspectives for a sustainable management of urban areas, with important fallouts in terms of economic and social issues. In this framework, some technical questions arise and different data processing strategies can be applied, depending on the scale of the analysis and the different processes evaluated; this paper, developed in the framework of a European research project in progress, tries to address some of these questions presenting the first results of a study carried out at city scale and related to the Urban Heat Island in Bologna, comparing three different algorithms for computing Land Surface Temperature. Although results are rather variable, the spatial distribution of surface temperatures is similar for all the methods we used: the presence of an urban heat island on the city is evident, and atmospheric validation data are needed to estimate its intensity.