结合2006年最新的气溶胶排放源资料,以NCEP/NCAR再分析资料为气象场,驱动大气化学传输模式MATCH(Model of Atmospheric Transport and Chemistry),模拟了2006年中国地区硫酸盐、黑碳和沙尘气溶胶的质量浓度分布及其季节变化。模拟的气溶胶光学厚度(AOD)结果与CSHNET观测网数据比较分析后发现,基于21个观测站的61组月平均数据与相应模拟结果的相关系数为0.63。模拟结果表明:2006年中国地区硫酸盐气溶胶高值区主要分布在中国的四川盆地、华北及长江流域等工业较发达地区,而且具有明显的季节变化,四川盆地及长江以南地区,硫酸盐气溶胶1月份浓度高于7月份,长江以北的大部分地区,7月份浓度高于1月份;黑碳气溶胶主要分布在黄河、长江中下游地区及华南等地区,1月份浓度高于7月份;沙尘气溶胶主要分布在内蒙古中部沙漠地区,4月份浓度最高,7月份次之,其他月份较少。
Aerosol indirect effects （AIEs） on global climate were quantitatively investigated by introducing aerosol–cloud interaction parameterizations for water stratus clouds into an AGCM （BCC AGCM2.0.1）, which was developed by the National Climate Center of the China Meteorological Administration. The study yielded a global annual mean of -1.14 W m^-2 for the first indirect radiative forcing （IRF）, with an obvious seasonal change. In summer, large forcing mainly occurred in mid to high latitudes of the Northern Hemisphere, whereas in winter, large values were found at 60°S. The second indirect effect led to global annual mean changes in net shortwave flux of -1.03 W m^-2 at the top of the atmosphere （TOA）, which was relatively significant in mid-latitude regions of both hemispheres. The total AIE reduced the global annual means of net shortwave flux at the TOA and of surface temperature by 1.93 W m^-2 and 0.12 K, respectively. Change in surface temperature induced by the total AIE was clearly larger in the Northern Hemisphere （-0.23 K） than in the Southern Hemisphere, where changes were negligible. The interhemispheric asymmetry in surface cooling resulted in significant differences in changes of the interhemispheric annual mean precipitation rate, which could lead to a tendency for the ITCZ to broaden. The total AIE decreased the global annual mean precipitation rate by 0.055 mm df^-1.
The study investigated the effects of global direct radiative forcing due to carbonaceous aerosol on the climate in East Asia, using the CAM3 developed by NCAR. The results showed that carbonaceous aerosols cause negative forcing at the top of the atmosphere （TOA） and surface under clear sky conditions, but positive forcing at the TOA and weak negative forcing at the surface under all sky conditions. Hence, clouds could change the sign of the direct radiative forcing at the TOA, and weaken the forcing at the surface. Carbonaceous aerosols have distinct effects on the summer climate in East Asia. In southern China and India, it caused the surface temperature to increase, but the total cloud cover and precipitation to decrease. However, the opposite effects are caused for most of northern China and Bangladesh. Given the changes in temperature, vertical velocity, and surface streamflow caused by carbonaceous aerosol in this simulation, carbonaceous aerosol could also induce summer precipitation to decrease in southern China but increase in northern China.
