Environmental System Thermal Immunity Index (ESTII) for Urban Heat Mitigation: A Landsat-Based Case Study of Al-Jadriya, Baghdad

Abstract

 This research develops and validates the Environmental Thermal Immunity Index (ETII), a novel composite satellite-derived index measuring urban fabric resilience to thermal strain. Unlike conventional vulnerability indices, the ETII analyzes urban thermal phenomena through the perspective of active thermal immunity rather than passive thermal exposure. The ETII combines four componentThis research proposes and tests the Environmental System Thermal Immunity Index (ESTII), a novel composite satellite-derived index measuring urban fabric resilience to thermal strain. Unlike conventional vulnerability indices, the ESTII analyzes urban thermal phenomena through the perspective of active thermal immunity rather than passive thermal exposure. The ESTII combines four component indices—NDVI, NDBI, Water Proximity, and surface albedo—through objectively derived Ridge regression weights. Applied to Al-Jadriya District, Baghdad, Iraq, the ESTII demonstrates a strong negative relationship with Land Surface Temperature (r = −0.958, R² = 0.917), outperforming any individual spectral index. Using Jenks Natural Breaks classification, three immunity classes are identified: Low (14.9%, mean LST 47.8°C), Medium (69.3%, mean LST 41.2°C), and High (15.8%, mean LST 33.1°C), revealing a thermal differential of 14.7°C within a single district. The ESTII shifts the conceptual reframing from measuring vulnerability to measuring immunity, providing Engineers with an evidence-based tool to direct heat mitigation efforts. indices—NDVI, NDBI, Water Proximity, and surface albedo—through objectively derived Ridge regression weights. Applied to Al-Jadriya District, Baghdad, Iraq, the ETII demonstrates a strong negative relationship with Land Surface Temperature (r = −0.958, R² = 0.917), outperforming any individual spectral index. Using Jenks Natural Breaks classification, three immunity classes are identified: Low (14.9%, mean LST 47.8°C), Medium (69.3%, mean LST 41.2°C), and High (15.8%, mean LST 33.1°C), revealing a thermal differential of 14.7°C within a single district. The ETII shifts the paradigm from measuring vulnerability to measuring immunity, providing planners with an evidence-based tool to direct heat mitigation efforts.