Characterization of Saharan and Middle Eastern dust aerosols and their associated shortwave direct radiative effects over Cyprus

Abstract

Atmospheric mineral dust modulates surface solar radiation, with important implications for regional climate and solar energy production. In this study, we investigate dust aerosol typing and associated shortwave (SW) direct radiative effects (DREs) using radiative transfer simulations over Cyprus using a 7-year dataset (2015–2022) from the Agia Marina Xyliatou station. Dust events were identified using AERONET optical properties, LIDAR observations, MODIS imagery, and classified by origin (Sahara or Middle East) based on HYSPLIT back-trajectories analysis. Dust accounts for ∼ 28.3 % of aerosol cases during spring (MAM) and ∼ 12.7 % during autumn (SON), with 86 % of events originating from the Sahara and 14 % from the Middle East. The mean AOD at 440 nm for the period studied here is 0.34 ± 0.13 for Saharan events and 0.40 ± 0.13 for Middle Eastern events, while the SSA at 440 nm remains high for both sources (0.93 ± 0.04 and 0.93 ± 0.03, respectively), indicating predominantly scattering aerosols. Radiative transfer estimates of global horizontal irradiance (GHI) agree well with ground-based irradiance measurements, with ∼ 87 % of modelled GHI values within ±5 % and ∼ 96 % within ±10 % of observations. Monthly DREs were evaluated for observations acquired at a common solar zenith angle (SZA ≈ 60 ± 4°). Under these conditions, the strongest monthly mean surface cooling reached approximately −92 W m −2 for Saharan dust and −86 W m −2 for Middle Eastern dust, while atmospheric heating reached approximately +72 and +59 W m −2 , respectively. The corresponding TOA cooling reached approximately −31 W m −2 for Saharan dust and −28 W m −2 for Middle Eastern dust. The mean surface SW DREs (for all SZAs) are −84 ± 49 W m −2 for Saharan dust in March and −79 ± 33 W m −2 for Middle Eastern dust in October. Although the Ångström exponent is slightly higher for Middle Eastern dust (0.37 vs. 0.30), suggesting enhanced fine-mode contribution due to aerosol mixing, radiative forcing efficiencies are comparable, indicating that aerosol loading primarily controls the magnitude of radiative perturbations.