Aerosol optical properties and its radiative forcing over Yulin,China in 2001 and 2002

The aerosol optical properties and direct radiative forcing over the Mu Us desert of northern China,acquired through a CE318 sunphotometer of the ground-based Aerosol Robotic Network (AERONET), are analyzed. Theseasonal variations in the aerosol optical properties are examined. The effect of meteorological elements(pressure, temperature, water vapor pressure, relative humidity and wind speed) on the aerosol optical propertiesis also studied. Then, the sources and optical properties under two different cases, a dust event and a pollutionevent, are compared. The results show that the high aerosol optical depth (AOD) found in Yulin was mostlyattributed to the occurrence of dust events in spring from the Mu Us desert and deserts of West China andMongolia, as well as the impacts of anthropogenic pollutant particles from the middle part of China in theother seasons. The seasonal variation and the probability distribution of the radiative forcing and theradiative forcing efficiency at the surface and the top of the atmosphere are analyzed and regressed usingthe linear and Gaussian regression methods.