High-Resolution Assessment of Surface Urban Heat Island Dynamics across Apulian Cities Using ECOSTRESS and Urban Atlas Data

Urban overheating is a growing concern in Mediterranean regions, where climate change and rapid changes in land use are intensifying thermal stress in cities. This study analyzes the spatial and diurnal variability of Surface Urban Heat Island Intensity (SUHII) in six major cities in Apulia (southern Italy)—Lecce, Brindisi, Taranto, Bari, Barletta–Andria–Trani, and Foggia—using multi-year summer Land Surface Temperature observations from ECOSTRESS (2018–2025) combined with Urban Atlas land-use information. SUHII was estimated at the pixel scale as the difference between urban LST and the median temperature of highly permeable rural areas, allowing for a consistent comparison among different urban settings, industrial/commercial zones, green spaces, and rural surroundings. Results reveal a common diurnal pattern, with negative or weak SUHII during the day and positive values after sunset, indicating stronger nocturnal heat retention within urban areas. However, this pattern varies substantially across cities. Coastal locations are strongly influenced by maritime conditions and sea-breeze circulation, which mitigate daytime thermal contrasts, whereas inland and densely built-up areas tend to exhibit more persistent warmth anomalies. Taranto stands out as the most distinctive case, with industrial and commercial areas maintaining positive SUHII values throughout much of the day, likely due to extensive impervious surfaces and industrial heat-related processes. Statistical comparisons confirm that industrial land uses often behave as thermally distinct environments, while vegetated and low-density areas generally show weaker anomalies. By integrating ECOSTRESS and Urban Atlas data, the study provides a transferable framework for characterizing fine-scale urban thermal heterogeneity in Mediterranean cities and supports future applications in urban climate modeling, heat-risk assessment, and climate-sensitive planning.