Comparison of the Direct Aerosol Radiative Forcing Efficiency from Ground-Based Remote Sensing Measurements in Al-Ain, Arabian Gulf region and Skukuza in Southern Africa

Utilizing the Surface-sensing Measurements for Atmospheric Radiative Transfer (SMART) mobile measurement suit, broadband solar irradiance was measured in Al-Ain during 2004 United Arab Emirates Unified Aerosol Experiment (UAE2) and in Skukuza during the Southern African Regional Science Initiative (SAFARI 2000). At both sites, the aerosol optical thickness was also measured by the Aerosol Robotic Network (AERONET) sunphotometers. These two sites in Arabian Gulf and Southern Africa provide a good opportunity for understanding how aerosols of different types in various environments influence the regional radiation budget. This can be seen through the lowered aerosol forcing efficiency in Al-Ain compared to that in Skukuza (measured about -180 vs. -200 Wm-2 respectively for airmass 1.2). One factor instigating this pheonemonon is the fact that particles in Skukuza created via biomass burning have a greater sunlight absorption capacity than that of the dust particles in Al-Ain. Model simulations are performed to help to explain the observation results.