A Study on Agricultural Fires and Aerosol Optical Depth in Peninsular India

Abstract. Agricultural fires are a major contributor to atmospheric pollution and play a significant role in regional climate forcing, accounting for nearly one-fourth of global biomass burning emissions. This study assessed the influence of agricultural burning on Aerosol Optical Depth (AOD) across Peninsular India during two contrasting years—2019 (a dry year) and 2024 (a normal rainfall year), as defined by deviations from long-term precipitation norms by the Indian Meteorological Department. Using VIIRS I-band (375 m) active fire detections and MODIS AOD (550 nm) observations, the study analyzed spatial patterns of fire activity and aerosol loading with high temporal and spatial resolution. Notably, fire counts increased by 9% in 2024 despite it being a wetter year, challenging the assumption that drier conditions necessarily drive more fire events. This unexpected rise in fires was accompanied by a 2–4% increase in AOD, with spatial analysis revealing a strong overlap between fire locations and elevated aerosol levels. These findings suggest that factors beyond rainfall variability— such as shifts in land management, post-harvest residue handling, or atmospheric stagnation—may influence fire dynamics, and that agricultural burning substantially contributes to regional aerosol accumulation regardless of hydrological year type. The study underscores the urgent need for targeted residue management and region-specific emission control strategies in South India.