Aerosol Optical Properties in the Eastern Arabian Peninsula from Direct Sun Observations

The Eastern Arabian Peninsula experiences elevated atmospheric particle loads due to anthropogenic emissions from the extraction and use of fossil fuels, as well as natural dust events, resulting in significant aerosol optical thickness (AOT). However, despite the region's significance, there is a lack of studies focusing on the optical and microphysical characterization of aerosols, leaving critical gaps in understanding their radiative effects. This study examines the optical properties of atmospheric particles over Qatar using more than one-year sun photometer data, with an emphasis on temporal variations and source origins. Measurements of direct sunlight were recorded every 5 minutes across wavelengths from 340 to 1020 nm between March 2023 and November 2024. Aerosol optical thickness (AOT) was calculated from these measurements using the Beer-Lambert-Bouguer law, while the Angstrom Exponent (AE) was derived to assess particle size. The results revealed notable daily variability, with average AOT values at 440 nm of 0.41 ± 0.21 and AE values averaging 0.87 ± 0.35. Seasonal patterns showed higher AOT during the summer months and a transition from dust-dominated to anthropogenic aerosols between March and December. Aerosols were classified into three categories: mineral dust-dominated (AE < 0.5), mixed (0.5 < AE < 1), and anthropogenic (AE > 1), accounting for 18%, 44%, and 38% of the total observations, respectively. These findings provide new insights into the aerosol composition over the region and emphasize the need for further research using radiative transfer models to evaluate aerosol-induced changes to the radiation budget.