Spatiotemporal Variability of Tropospheric NO₂ and Aerosol Optical Depth in Lahore Division

This study examines the spatiotemporal variations of tropospheric Nitrogen dioxide (NO₂) and Aerosol Optical Depth (AOD) over the Lahore Division, utilizing satellite and ground-based data spanning from 2006 to 2023. The findings indicate consistently elevated NO₂ levels, attributed to the dense population, industrial activities, and crop residue burning, with mean values ranging from 3.87 to 6.34 × 10¹⁵ mole/cm². A seasonal analysis for the period 2021–2023 revealed heightened NO₂ concentrations during winter and autumn, with peaks observed in winter 2022 (4.86–8.09 × 10¹⁵ mole/cm²) and autumn 2021 (4.18–6.85 × 10¹⁵ mole/cm²), reflecting post-COVID-19 recovery trends. AOD variations demonstrated higher values in summer and fall (0.5–0.69), predominantly influenced by fine-mode aerosols, with an increasing trend post-COVID-19. The summers of 2021, 2022, and 2023 recorded peak AOD levels (0.68–1.10, 0.75–0.93, and 0.91–1.14, respectively). In 2023, a strong positive correlation (r = 0.02 to 0.19, R = 0.13) suggested an increase in anthropogenic emissions due to urbanization. The changes in NO₂ and AOD patterns from 2019 to 2023 underscore the impact of COVID-19-related restrictions on industrial, commercial, and transportation activities.