Saharan and Arabian dust optical properties registered by sun photometry during A-LIFE field experiment in Cyprus

Abstract. The A-LIFE (Absorbing aerosol layers in a changing climate: aging, lifetime, and dynamics) field experiment in Cyprus (April 2017) employed a wide range of ground-based and airborne instruments, including passive/active remote sensing and in-situ techniques. This study presents the columnar records obtained by sun photometry. Two sun/sky/lunar photometers, belonging to AERONET network, were strategically placed at two different sites: Pafos and Limassol, 40 km apart. Aerosol optical and microphysical properties derived from direct sun and sky radiance measurements are analysed to determine an inventory of aerosol event days during the whole experiment, with mineral dust being predominant. Obtained Ångström exponent values in the near-infrared range (0.5 for Saharan dust and 0.34 for Arabian dust) can served as a classification criterion. Dust sources are the key point for a well understanding of the size distribution and absorption power. Saharan dust exhibited smaller and less absorbing particles than Arabian dust. The columnar volume efficiency factor (linear fit between aerosol optical depth and total volume concentration) was proved as a reliable proxy for the identification of dust origin since Arabian and Saharan dusts exhibit different slopes: 1.28 and 1.68 μm²/μm³, respectively. Mixtures of mineral dust were mainly dominated by Arabian dust, while mixtures of fine and coarse aerosols showed no clear prevalence of dust origin. No significant presence of black carbon-rich aerosols was detected in the atmospheric column, as absorption Ångström exponent values ranged from 1.6 to 3 across aerosol types identified in the inventory of A-LIFE experiment.