Operational AOD Retrieval at Subkilometer Resolution Using OceanSat‐2 OCM Over Land: SAER Algorithm, Uncertainties, Validation & Inter‐Sensor Comparison

The ocean color monitor (OCM) sensor onboard OceanSat-2 is providing data in visible and near Infrared (NIR) bands. Due to the limited spectral coverage of OCM, widely used dark-target deep-blue aerosol algorithms cannot be adapted. Here, a new optical depth (AOD) retrieval algorithm for OCM (or similar sensors) over land, termed Space Applications Center AErosol Retrieval (SAER) described. It utilizes two blue bands AOD inversion and, Red NIR band characterize surface without assuming red transparent aerosols. Unlike algorithm, SAER can retrieve bright arid urban areas too. uncertainty analysis suggests theoretically expected error (EE) envelope ±(0.06 + 0.26 × AOD) typical conditions. land retrieved operationally first time Indian neighboring countries' landmass at finest spatial resolution 0.007°. validated against in-situ measurements during years 2016–2018 21 Aerosol Robotic Network stations located south-Asia. Overall validation using 1900 match-up points shows correlations exceeding 0.8 with 74% retrievals within EE. cropland, grassland, mixed cover types show high (low) correlation (bias), while somewhat low (high) (bias) observed. Excluding monsoon season, good performance year. MODerate Resolution Imaging Spectroradiometer AOD, common in-situ, close each other. study that air quality monitoring/modeling resolution.