Numerical Simulations Of The Radiative Forcing Of Black Carbon And Sulfate Aerosol And The Effect On Regional Climate In China

The regional Climate Model version 3(RegCM3)is used to investigate the radiative forcing of black carbon(BC)and both BC and sulfate aerosol(complex aerosol for short)in China.The possible effect of the aerosol on regional climate is analyzed.The main work of this study can be summarized as follows:1.By use of RegCM3,the distribution of aerosol emissions is analyzed,the column burden and optical depth of BC and complex aerosols are simulated.It is revealed that main heavy loading regions of BC existing in China are the regions which have more people and developed industry,indicating that the emissions and column burden of aerosols are related to the human activity,and the BC loading follows a clear seasonal cycle.The distribution of optical depth also changes following the different area and season prominently.2.The temporal and Spatial distribution of radiative forcing of BC and sulfate aerosols is estimated,and then the change of mean in latitude direction is discussed. The simulation results show that BC aerosol induces a positive radiative forcing at the top of the atmosphere,which is mainly located in the Mid-Lower Reaches of the Yangtze River and it extends northeastward in summer and autumn.The distribution of negative forcing on the surface is correspond to the optical depth.The radiative forcing induced by the complex aerosol is larger than the BC aerosol.3.On the base of investigating the radiative,forcing,the possible effect of the aerosols on regional climate is analyzed.It is found that the response of the climate system in summer to the radiative forcing due to BC aerosol is clear and shows seasonal characteristics,that is,in winter,the surface temperature increases in most of the region,whereas it increases in northern China and decreases in southern China in summer.After the adding of sulfate aerosol,it indicates a smaller increase in North China,Northeast and Southwest of China,and a smaller decrease in Northwest and South China in winter,whereas,it is not obvious in summer.The results also show that the total rainfall in the Mid and lower reaches of the Yangtze River is increased because of BC aerosol,but it is decreased in some regions in northern China.The influence of the complex aerosols on the rainfall is not obvious, showing that the sulfate aerosol counteracts part of the effect on the rainfall due to the BC aerosol.