Decadal Characterization of Satellite-based Aerosol Types Over Arabian Peninsula: Comprehensive Insight and General Performance

Retrieving aerosol characteristics such as particle size, shape, and absorption properties is a big challenge in satellite-based remote sensing, mainly for the single-viewing-angle instrument. Multi-angle instruments such as Multi-angle Imaging Spectroradiometer (MISR) measure the reflected radiation from nine viewing angles, allowing the retrieval algorithm to accurately distinguish different aerosol microphysical and optical properties along with total aerosol loading in the atmospheric column. Recently, MISR upgraded the aerosol retrieval algorithm version 23 (V23) and enhanced the spatial resolution of the aerosol products to 4.4km, enabling the study of the aerosol characteristics at a finer scale. This study uses 20 years of MISR V23 aerosol products to comprehensively investigate aerosol optical and microphysical properties and their performance over Gulf Cooperation Council (GCC) countries using two decades of aerosol products from the MISR algorithm. The assessment of MISR AOD showed good agreement with ground-truth AOD from AERONET, with ~75% of retrieval falling within the expected error (0.05±0.2AOD) and a high Pearson’s correlation coefficient (R = 0.86). However, MISR relatively underestimates AOD at higher aerosol loading conditions (AOD>0.6) while overestimating coarse-dominated aerosol mixture (Angstrom Exponent <0.7). The 20 years mean MISR AOD showed higher aerosol loading dominated by coarse aerosol types over the Eastern province of Saudi Arabia and Rub’al Khali. Seasonally, the size-fractionated AOD showed that GCC countries dominated by coarse AOD (cAOD) and non-spherical aerosol particles mainly in Spring, while the contribution of small AOD (sAOD) to the total range from 42-45% for Winter and Autumn. Overall, the high spatial resolution of MISR aerosol data products has a great potential to identify an aerosol hot spot and constrain the aerosol types, mainly dust, across the highly polluted region in the Middle East.