Comparison of Aerosol Properties over Six Major Deserts from Africa to Asia Using AERONET and CALIPSO Observations

Abstract

Abstract The characteristics of aerosols in deserts and dust-affected regions were investigated using datasets from 11 Aerosol Robotic Network (AERONET) sites and Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations ( CALIPSO) retrievals across six major desert regions (Sahara, Arabia, Thar, Karakum, Taklamakan, and Gobi) from 1998 to 2021. The results show a similar seasonal variation in aerosol optical depth (AOD), with maxima typically in summer and spring, and minima in winter. Despite some shared features, significant regional differences were observed in AODs, Angstrom exponents (AEs), and fine-mode fractions (FMFs) across these deserts. The analysis indicates that dust particles contribute most to total extinction in the Sahara, whereas fine particles dominate in the Gobi (FMF of ∼63%). Seasonal variation in aerosol-absorbing properties differs significantly between the desert edges and cores due to the diverse contributions of different aerosol types. Different deserts exhibit distinct ranges of mean absorption AOD (AAOD) (0.03–0.06), dust AAOD (0.01–0.03), absorption AE (AAE) (1.16–2.81), and single-scattering albedo (SSA) (0.84–0.94). The Sahara aerosol exhibited the highest absorption loading, while the Taklamakan aerosol demonstrated the strongest light-absorbing ability, as reflected by its lowest SSA. Variations in aerosol compositions and size contribute to a wide range of AAE values in these deserts, with the highest (2.81) in the Sahara and the lowest (1.16) in the Taklamakan. Desert dust dominates year-round, with seasonal contributions from polluted dust and elevated smoke, as observed by CALIPSO . Direct aerosol radiative forcing (DARF) was highest over the Arabia and Thar Deserts, and lowest over the Gobi, whereas the DARF efficiency (DARFE) peaked in East Asia and was lowest in the Thar Desert. Significance Statement This study provides a comprehensive characterization of aerosol optical and radiative properties across six major deserts of the Northern Hemisphere using more than two decades of Aerosol Robotic Network (AERONET) and CALIPSO observations. Unlike previous studies that focused mainly on dust loading, this work reveals distinct regional and seasonal variability in aerosol composition, absorbing properties, and radiative forcing effects, highlighting the mixing effects of pure dust particles with other pollution aerosols, such as polluted dust and smoke. By quantifying the variations in aerosol absorption [absorption AOD (AAOD) and single-scattering albedo (SSA)] and radiative impacts [direct aerosol radiative forcing (DARF) and DARF efficiency (DARFE)] across desert regions, this study improves the representation of aerosol–radiation interactions in models. These findings are critical for reducing uncertainties in regional climate simulations, enhancing aerosol parameterizations in climate models, and improving air quality forecasting in regions affected by desert and transported aerosols.