Atmopheric Aerosols Pollution And Their Radiative Forcing Over Beijing Area

The heavy aerosol pollution can not only affect the environment but also directly and indirectly affect the local and global’s climate. Aerosols absorb and reflect the solar radiation, and reduce the radiation energy reaching the surface, and thus change the energy income and outgo in the boundary layer. The topic of the aerosol direct radiative forcing (ADRF), and associated urban pollution and atmospheric boundary layer, are addressed by many scientists.This thesis analyzes the observed data of radiation, aerosols and polluted gases that were measured in fall and winter2004in Beijing, and in springtime2006in Beijing and Baodi of Tianjin, respectively. Changes can represent different polluted conditions for different periods in Beijing and the difference of pollution in different local (urban and suburb) in the same period. The property of aerosols is taken into account to model all kinds of radiation. The radiative forcing for the total solar radiation, and ultraviolet are calculated. The effects of aerosols on the radiation and the structure of boundary layer are found. The detailed results are summarized as below.The pollution of Beijing in fall and winter has a distinct cycle of5-6days. The low visibility haze and fog are the mainly pollution case in that period. The pollution of Beijing is much heavier than that of Tianjin-Baodi in the same period. The aerosols are of much more high absorption in Beijing fall and winter than those in spring. The effect of aerosol on radiation is also inequable.The aerosol can weaken the radiation greatly not only in clear days but also in heavy polluted days. In a good clear day the difference of downward radiation at2m and280m can get100Wm-2All kinds of shortwave radiation reduced greatly with the pollution get heavy. The difference radiation of2m and280m also gets small. The SWD (short wave downward) radiation at noontime at280m height changed from554Wm-2to208Wm-2from good clear day (26th Oct) to heavy polluted day (30th Oct).Tianjin Baodi than the Beijing air quality is good, good weather observation period up to82%。 Both in Beijing or Tianjin Baodi, SO2, NO, NO2, CO and ozone changes are invert.On good clear day the radiative forcing on the surface over Beijing winter can get-46±14Wm-2whlie the radiative forcing in Tianjin-Baodi is-25±2Wm-2. On heavy haze day the direrct radiative forcing on surface over Beijing can get-111Wm-2.The structure of boundary layer affect the aerosol’s distributing. The inversion and weak wind are the important reason to lead the polluted process. It is also found that the solar radiation near the surface have a negative correlation with the mass concentration of aerosols measured at the same time. The daily temperature range is found to become smaller due to aerosol’s effect since the daily maximum temperature during the daytime decreases with the solar radiation decrease and the daily minimum temperature at night increases with the net long-wave radiation decrease. Since the temperature effect of aerosols decreases with height, the strength of inversion layer at night is found to become smaller in heavy pollution days.