Assessing the impact of urban expansion to the state of thermal environment of peri-urban areas using indices

In this paper we assess the impact of urban expansion to the thermal environment in peri-urban areas in the urban agglomeration of Athens for the period 1994-2010. Firstly, indices based on the use of earth observation data are used to distinguish urbanized from non-urbanized areas, and define built up features and area evolution at high spatial resolution. The urban expansion of Athens is more pronounced to the north and the west of the city, as well as to the south along the coastline. Secondly, the thermal environment is studied through the estimation of land surface temperature (LST) using Landsat satellite data. Areas, where land cover change has occurred due to urban expansion, show significantly smaller LST differences over the years as compared to a reference area in the urban center; a continuum of similar LST values extends from the city center to the peri-urban areas. This finding is of importance regarding urban climate as a temporal modification of the LST pattern in the peri-urban areas of Athens over the years, may potentially impact energy exchange, local circulation patterns, thermal comfort as well as energy consumption for cooling.