EFFECTS OF AEROSOLS ON AUTUMN PRECIPITATION OVER MID-EASTERN CHINA  

作　　者：陈思宇 黄建平 钱云 葛觐铭 苏婧 

机构地区：[1]Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, Lanzhou University [2]Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, USA

出　　处：《Journal of Tropical Meteorology》2014年第3期242-250,共9页热带气象学报（英文版）

基　　金：National Basic Research Program of China(2012CB955301)

摘　　要：Long-term observational data indicated a decreasing trend for the amount of autumn precipitation(i.e. 54.3 mm per decade) over Mid-Eastern China, especially after the 1980s(~ 5.6% per decade). To examine the cause of the decreasing trend, the mechanisms associated with the change of autumn precipitation were investigated from the perspective of water vapor transportation, atmospheric stability and cloud microphysics. Results show that the decrease of convective available potential energy(i.e. 12.81 J kg-1/ decade) and change of cloud microphysics, which were closely related to the increase of aerosol loading during the past twenty years, were the two primary factors responsible for the decrease of autumn precipitation. Our results showed that increased aerosol could enhance the atmospheric stability thus weaken the convection. Meanwhile, more aerosols also led to a significant decline of raindrop concentration and to a delay of raindrop formation because of smaller size of cloud droplets. Thus, increased aerosols produced by air pollution could be one of the major reasons for the decrease of autumn precipitation. Furthermore, we found that the aerosol effects on precipitation in autumn was more significant than in other seasons, partly due to relatively more stable synoptic systems in autumn. The impact of large-scale circulation dominant in autumn and the dynamic influence on precipitation was more important than the thermodynamic activity.Long-term observational data indicated a decreasing trend for the amount of autumn precipitation （i.e. 54.3 mm per decade） over Mid-Eastern China, especially after the 1980s （- 5.6% per decade）. To examine the cause of the decreasing trend, the mechanisms associated with the change of autumn precipitation were investigated from the perspective of water vapor transportation, atmospheric stability and cloud microphysics. Results show that the decrease of convective available potential energy （i.e. 12.81 J kg^-1/ decade） and change of cloud microphysics, which were closely related to the increase of aerosol loading during the past twenty years, were the two primary factors responsible for the decrease of autumn precipitation. Our results showed that increased aerosol could enhance the atmospheric stability thus weaken the convection. Meanwhile, more aerosols also led to a significant decline of raindrop concentration and to a delay of raindrop formation because of smaller size of cloud droplets. Thus, increased aerosols produced by air pollution could be one of the major reasons for the decrease of autumn precipitation. Furthermore, we found that the aerosol effects on precipitation in autumn was more significant than in other seasons, partly due to relatively more stable synoptic systems in autumn. The impact of large-scale circulation dominant in autumn and the dynamic influence on precipitation was more important than the thermodynamic activity.

关 键 词：AEROSOL autumn precipitation atmospheric stability cloud microphysical properties 

分 类 号：X513[环境科学与工程—环境工程]