Urban Heat Island analysis with Remote Sensing and GIS methods: an application in the Trieste area (North-East of Italy)

It is a well-known fact that many factors increase urban outdoor temperature. Urban landscape and buildings design that does not consider this specific issue is probably the most important cause of the so called Urban Heat Island effect (UHI). Furthermore, loss of vegetation and of pervious surface cover can increase the intensity of the UHI effect. Specialist knowledge of the impact of the UHI growth factors on the urban microclimate is of the upmost importance for the adoption of efficient mitigation measures. This paper uses Remote Sensing and GIS methods in order to investigate the main impact factors of the UHI in the Province of Trieste (the capital of the Friuli Venezia Giulia Region, North-East of Italy). With this aim, the surface temperature is considered from a medium spatial resolution remote sensed image and these data are cross-checked with the local albedo, the urban vegetation and building density. The main results of the paper are of a geographical kind. The remote sensing methods showed that, in the area studied, there was a strong correlation between higher temperatures and building density and the absence of vegetation. This is particularly evident in the urban environment of the city of Trieste (but it also occurs in the small villages of the surrounding area).