Local climate zones in five southern European cities: An improved GIS-based classification method based on Copernicus data

Abstract

While climate change projections for the Mediterranean region indicate an increased exposure to heatwaves (HW), such prospects are particularly challenging in urban areas, where thermal stress can be exacerbated by the Urban Heat Island (UHI) effect. In that regard, understanding spatial patterns of thermal performance is of the utmost importance, in order to address corresponding adaptation measures. Local Climate Zones (LCZ) have become the standard typification of Land Cover/Land Use classes, according to their climatic response. However, the corresponding satellite-based classification method from the World Urban Database and Access Portal Tools (WUDAPT) presents accuracy issues when applied to European cities. Several studies have provided alternative LCZ methodologies, but these usually require data which is not often readily available (e.g. high-resolution digital surface models), therefore rendereing them hard to replicate. This study addresses this issue by developing an alternative geographic information system (GIS)-based method, and the corresponding toolbox, to translate Copernicus datasets into LCZ maps: Urban Atlas and Corine Land Cover shapefiles are used as the baseline dataset for the reclassification. The method was proven to be accurate in the five cities used in the case study - Athens, Barcelona, Lisbon, Marseille, and Naples - 81% overall accuracy, and 0.79 Kappa coefficient, on average. Results reveal the presence of a diurnal surface UHI, with lower land surface temperatures (LST) found in tree covered areas. However, similar LST found in the other LCZ classes (e.g. between compact and sparsely built-up areas) indicates that diurnal patterns of the urban energy balance components must be considered to better characterise the UHI of these cities.