The project uses very high resolution (VHR) satellite imagery from the Pleiades mission. Using a detailed description of the urban fabric, the aim is to implement a reproducible methodology to develop indicators based on the Local Climate Zone (LCZ) concept developed by the international urban climatology community [Stewart & Oke 2012]. This method segments areas into homogeneous elementary typo-morphological units based on their climatic behaviour. The project’s objectives relate to the vulnerability of the urban environment during summer heat waves, as well as to local efforts to adapt and attenuate heat peaks through better urban design. Identifying LCZs involves producing geographical layers describing urban morphology (four indicators) and land use (three indicators). A study [Leconte et al. 2018] shows that the intensity of the heat island and these indicators can be correlated to the surface scale of the LCZ.
The project follows up the DIACLIMAP project financed by the ADEME (French environment and energy management agency) between 2015 and 2017. DIACLIMAP developed a method using VHSR imagery to produce LCZ indicators for the Greater Nancy area cross-referenced with locally measured microclimatic data [10th ICUC, Bouyer et al.]. Indicators are calculated using 3D frames with layers of “impermeable surfaces” and “permeable surfaces” taken from the imagery as well as a digital surface model also taken from satellite imagery.
The use of VHR imagery makes it possible to produce and update LCZ indicators for any type of urban fabric, with or without such rich geographical databases as those in France. The project therefore seeks to extend the method developed for France to other countries, adapting the classification to varying urban contexts and establishing a processing sequence running from satellite imagery through to the production of indicators, automating processes wherever possible.
In the first instance, this method will be applied to the area of Greater Lille which experienced a heatwave with temperatures of over 41°C in 2019. Data from this region will be used to validate the results of the method employed with existing data (Pleiades imagery, digital surface model). In the second instance, a city in another country will be included to verify the method’s transposability.
Territories for experimentation
- Lille, France
Results - Final products
- A spatial distribution indicator of the urban heat island phenomenon
- Digital terrain model
- Land use map
- Classed as a Local Climate Zone