Evaluating intra-urban thermo-hygrometric variability through in situ observations and MLUCM BEP + BEM: A case study in Lecce (Italy)

This study evaluates the capability of the MLUCM BEP + BEM to reproduce intra-urban variability of air temperature and relative humidity in Lecce (Italy) during summer 2025. A network of six measurement sites representing contrasting urban morphology, vegetation cover, and land-use conditions was used to characterize the thermo-hygrometric structure of the city and evaluate model performance. Site-specific simulations were driven by identical upper-boundary meteorological forcing, allowing the contribution of the explicit urban representation to spatial variability to be isolated, while ERA5 fields were spatially interpolated to each measurement site. Observations showed warmer and generally drier conditions in more densely urbanized areas and cooler, more humid nocturnal conditions in greener and less compact districts. Although ERA5 generally yielded lower pointwise errors, MLUCM BEP + BEM generated substantially greater site-to-site differentiation. The model reproduced about 18% and 31% of the observed mean intra-urban temperature and relative-humidity ranges, respectively, compared with near-null spatial variability in ERA5. Pairwise analysis further showed a markedly improved representation of maximum-temperature contrasts, although the magnitude of spatial differences, particularly at night, remained underestimated. These results indicate that the main contribution of MLUCM BEP + BEM lies in representing differentiated responses among urban configurations, supporting its application to urban heat exposure, thermal comfort, and climate-adaptation studies.