A Multivariate Geostatistical Framework to Assess the Spatio-Temporal Dynamics of Air Pollution and Land Surface Temperature in Bangladesh

In the context of escalating urban heat dynamics, the effect of air pollutants on Land Surface Temperature (LST) is an urgent concern, especially in the Global South. These regions are experiencing rapid industrialization, leading to an increase in greenhouse gas concentrations. Although the heat-absorbing capacity of air pollutants is well-recognized, the spatiotemporal relationship between these pollutants and LST remains underexplored, particularly in densely populated and industrialized metropolitan areas. Moreover, studies examining multiple pollutants simultaneously to understand their cumulative impact on surface temperature anomalies are scarce. Our study addresses this research gap by developing a spatial-temporal framework using remote sensing data from Google Earth Engine (GEE). We assessed the levels of Nitrogen Dioxide (NO2), Carbon Monoxide (CO), Aerosol Optical Depth (AOD), Ozone (O3), Sulfur Dioxide (SO2), and Formaldehyde (HCHO) in Bangladesh. Utilizing Emerging Hotspot Analysis and Geographically Weighted Regression (GWR) and complementing these with Principal Component Analysis (PCA) to create a Pollutant Impact Index (PII), we provide a detailed understanding of pollutant's impact on LST. The results revealed a global R-squared value of 0.61 with maximum local R-squared value of 0.68. Over 30% of the areas studied exhibit high-high clusters for air pollutant coefficients, with notably alarming levels of NO2 and O3, affecting 48.53% and 54.67% of the area, respectively. The PCA underscored the significant role of these pollutants, with the first three principal components accounting for 75% of the variance. Notably, the spatial distribution of the PII across Bangladesh showed substantial regional variations. Urban areas, like Dhaka and Sylhet, exhibited much higher PII values compared to less industrialized regions. These insights highlight the need for targeted environmental strategies to mitigate the impact of air pollution on urban heat dynamics and public health. The study's findings underscore the urgency of addressing these environmental challenges, particularly in rapidly developing areas of the Global South.