Built Environ. The growth of a city is typically accompanied by densification and sprawl, the former through verticalization, urban renewal, and the filling in of empty spaces. All of these activities extend and intensify the urban heat island UHI , which is quantified in this study as the difference in daily minimum temperature between urban and rural areas.
Here, we investigate this phenomenon in the area of Rennes France and 17 surrounding cities using the Rennes Urban Network which comprises 93 weather stations. This study aims to 1 determine the optimal method for spatializing UHI in Rennes, France, 2 estimate and spatialize the UHI in the small peri-urban cities surrounding Rennes.
This approach allows stochasticity to be taken into account, and thus provides a better representation of UHI variation within Rennes and its peri-urban cities. The urban heat island UHI effect is a climatic phenomenon caused by the expansion and verticalization of a city. Compared to the semi natural environment, the low vegetation density in cities, along with the high amount of artificial surfaces, lead to reduced evapotranspiration.
The net radiation is stored in building materials, causing heat accumulation during the day and release at night, resulting in higher temperatures Oke, ; Landsberg, ; Oke, Most efforts have focused on large sized cities Cantat, ; Oswald et al. Indeed, knowing and assessing the intensities of UHI observed in medium and small cities will enable to support public policies in new urban planning for more people. This study maps the UHI of the city of Rennes medium size and the surrounding peri-urban small cities, a region who have known an economic attractiveness which has led to intensive urbanization of the peri-urban cities in recent years.
UHI monitoring can be performed using data from fixed meteorological stations or transect measurements, or with thermal infrared data obtained by remote sensing land surface temperature. Sometimes, a combination of several approaches is employed Amorim et al.
