摘要
Ground-based and satellite observations indicated heavy anthropogenic absorbingaerosol loading overthe Beijing metropolitanarea from 2004 to 2011.The annualmeans of the aerosoloptical depth (AOD),Angstrom exponent,single scatteringalbedo (SSA) and aerosol direct radiative forcing were 0.40±0.04,1.28±0.07,0.89±0.09and0.093±0.032W/mzW/mzat 550nm in Beijing City,0.51±0.05,1.16±0.06,0.87±0.09,and 0.104±0.024in the Xianghe suburb,and 0.20±0.02,0.99±0.05,0.88±0.08,and0.045±0.018W/m`in the background readings, respectively.aerosol optical and radiative characteristics had strong seasonal variations inregion,and there were large differences wereapparent from the levels in the cityto the background levels.The aerosol direct radiative forcing in the region washighest in summer:0.115±0.074W/mz in Bei jing City,0.142±0.045W/mz in the suburband 0.071±0.O1W/m`in the background readings. The annual aerosol direct radiativeforcing trend showed a slight decline in Beijing City,while the trend in thebackground levels rose in recent years.