Performance Assessment of MODIS Dark Target and Deep Blue Aerosol Retrieval Algorithms Using AERONET Observations: A...

Aerosols significantly impact climate by interacting with solar radiation and altering cloud properties. Satellite-based measurements provide extensive coverage for evaluating aerosol optical characteristics, particularly in regions like India with limited ground observations. This study assesses and compares MODIS (Moderate Resolution Imaging Spectroradiometer) Collection 6.1 AOD (Aerosol Optical Depth) products from Terra and Aqua satellites using AERONET (AErosol RObotic NETwork) data from Jaipur and Karunya University for 2017-2018. The MODIS Dark Target AOD, at 10 km (DT_10km) and 3 km (DT_3km) resolutions, and Deep Blue AOD, at 10 km (DB_10km) resolution, are validated against AERONET-derived AOD. It is found from the validation that the DT_3km algorithm demonstrated better performance in terms of data points falling within the error boundary at both research sites, which indicates the superiority of that product for both satellites. The AERONET and MODIS monthly mean AOD derived from Terra and Aqua, satellite retrieval algorithms, are compared. Additionally, the AODs acquired from the DT and DB algorithms of the MODIS Aqua and Terra satellites over India in May, July, and November of 2018 are analysed using the Giovanni tool. The result indicates that the IGP (Indo Gangetic Plain) region places experience higher AOD values. The AOD values were comparatively higher in India during July 2018 than in the other two months considered. It was found that the DT algorithm retrieves higher AOD values than the DB algorithm. This paper recommends the DT algorithm for India's AOD retrieval.