Study of aerosol optical properties in the Middle East

Aerosols affect the earth s atmospheric radiative fluxes via direct, semi-direct, and indirect mechanisms and they canbe regarded as a major source of uncertainty in climate forcing assessments. In the Middle East, in addition to climateeffects, various problems such as reduction of the visibility, human health hazards and air pollution are caused byatmospheric aerosols. Studying optical and physical properties of aerosols on a local and global scale helps reduce theuncertainties in climate forcing. In this study, aerosol optical properties like Aerosol Optical Depth (AOD), AngstromExponent (AE), ASYmmetry parameter (ASY), Single Scattering Albedo (SSA) and phase function have beenanalyzed. These properties have been studied in five sites in the Middle East region during 2013 using the AerosolRobotic NETwork (AERONET) data. The results revealed an inverse relationship between AOD and AE for all sites.The high value of AOD and low value of AE were observed in the spring and summer in all studied sites that wereindicative of coarse mode particle and dust storms in these seasons. As wavelength increased, ASY Initially decreaseddue to the dominance of absorbing aerosol in the visible spectrum, whereupon the ASY increased with growingwavelength in the infrared region due to the dominance of the coarse mode particles. In most sites, as a result of thedominance of desert dust, SSA increased especially in the spring and summer proportionate to the increase in thewavelength. In the spring and summer, the phase function was high in all sites. High phase functions for smallscattering angles were due to the coarse mode particles. Phase function was reduced uniformly in angles between 0-10 degrees due to the presence of fine mode particles.

کلیدواژه ها:

SBDART ، AERONET ، Middle East ، Aerosol Optical Depth ، Aerosol Physical Properties