Comparing urban heat islands in Erbil city-Iraq: Investigating vegetation response through day and night thermal infrared data and NDVI values

Land surface temperature (LST) is crucial in understanding urban environments, climate dynamics, hydrology, ecology, and agriculture. While daytime thermal infrared (TIR) data from satellites have been extensively used to analyze LST and the urban heat island effect in arid regions, exploration of nighttime LST data over semi-arid urban areas using high-resolution TIR data is lacking. This study aims to investigate spatial and temporal Land Surface Temperature (LST) variations in Erbil City, located in the Northern part of Iraq, utilizing high-resolution Landsat-8 data for daytime analysis and ECOSTRESS data for nighttime evaluation. The research reveals distinct daytime Urban Cooling Intensity (UCI) and significant nighttime Urban Heat Island (UHI) effects, with UCI primarily driven by early morning Landsat imagery. Notably, a prominent UHI effect occurs at night, particularly in May and June. Daytime LST values show no significant differences among land cover categories, while nighttime LST decreases in areas with Normalized Difference Vegetation Index (NDVI) > 0.5. The study emphasizes the importance of high-resolution nighttime TIR data in investigating UHI in arid and semi-arid regions, addressing a gap in prior research that overlooked this aspect. The prevailing hot and arid climate weakens vegetation’s thermal buffering capacity during warmer months, resulting in the absence of distinct temperature variations in the study area.