Urban heat island and pollutant correlations in Bangalore, India using geospatial techniques

Abstract

The interaction between urban heat island (UHI) effects and urban air pollution significantly impacts urban ecology, climate dynamics, and inhabitants' well-being. This study examines into the correlation between UHI effects and various pollutants (CO, HCHO, aerosols, NO₂, O₃, and SO₂) across Bangalore from 2019 to 2022, exploring their spatial and thermal connections. The study utilized satellite remote sensing data from TROPOMI for air pollutants (CO, NO₂, HCHO, SO₂, O₃, and aerosols) and MODIS for land surface temperature (LST). Data were collected over a four-year period (2019–2022) to analyze spatial and temporal pollutant distributions and UHI effects in Bangalore and employed statistical methods, including Pearson correlation, independent t-tests, and ANOVA, to assess the relationships between UHI indicators and pollutant concentrations. A weighted Urban Pollution Island (UPI) index was developed using Fuzzy AHP, while thermal categorization was achieved through spatial analysis techniques. Research indicates significantly elevated pollution levels in urban areas compared to rural regions. The research demonstrates positive correlation between UHI indicators and CO, HCHO, aerosols, NO₂, and O₃ in urban-rural environments. A negative correlation is observed between the UHI indicator and SO₂ in these contexts, requiring a thorough investigation of the UHI-pollutant relationship. High-risk zones (HRZs) demonstrate significantly elevated yearly average concentrations of NO₂ (66.614%), aerosols (13.610%), HCHO (8.816%), and CO (2.028%) relative to low-risk zones (LRZs). Ozone levels are consistently similar between HRZs and LRZs. In contrast, LRZs demonstrate a greater yearly average concentration of SO₂ (7.562%) than HRZs. Furthermore, HRZs exhibit an elevated LST of 2.198 °C relative to LRZs. These results yield essential insights for urban planning and policy development, providing a thorough comprehension of UHI pollution dynamics. This research clarifies these dynamics, aiding informed decision-making to mitigate the effects of UHI and pollution in urban settings.