Validation of operational oceansat-3 ocean colour monitor aerosol optical depth product over land using AERONET ground observations

We present the first comprehensive validation of the operational OCM-3 550 nm aerosol optical depth (AOD) product over land, retrieved using the SAC AErosol Retrieval algorithm over South Asia. By using nearly 22 months of data (June 2023–March 2025) collocated with 13 AERONET stations, the study evaluates the product’s accuracy across different land cover types and aerosol regimes. The overall agreement of R = 0.85, RMSE = 0.20, MAB = 0.15, and 70% of matchups within the expected error envelope (N‐EE), based on N = 831 collocations, is found. Leveraging OCM‐3’s 1 km resolution, we assess performance over urban hotspots, agricultural plume regions, and other localized emission areas. Validation by land-cover type shows the highest accuracy over croplands ( R = 0.91, RMSE = 0.19) and identifies a lower retrieval slope (0.67) in urban environments. Seasonal composites confirm the reliable capture of pre‐monsoon peaks, sustained monsoon AOD under high humidity, post‐monsoon resurgence, and winter accumulation. The high spatial resolution (1 km) enables mapping of fine-scale aerosol features, enhancing monitoring of urban pollution hotspots, crop residue burning regions, and localized sources. The results provide confidence in the operational use of OCM-3 AOD for high-resolution environmental monitoring, air quality applications and climate research.