Volume 15, No. 4, August 2015, Pages 1367-1379 PDF(3.17 MB)
Inter-Annual Variations of Cloud and Precipitation and their Possible Relationships with Surface Aerosols in Shanghai
Deqin Zhang1, Chen Xu1, Junyan Duan1, Yifan Wang1, Jianfei Du2, Shuping Zha1, Chunpeng Leng1, Xiang Li1, Tiantao Cheng1,3, Jun Tao4, Renjian Zhang5
1 Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, China
2 Shanghai Meteorological Bureau, Shanghai 200030, China
3 Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China
4 South China Institute of Environmental Sciences, Ministry of Environmental Protection, Guangzhou 510655, China
5 Key Laboratory of Region Climate-Environment Research for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
- AOD and visibility become more serious, while PM10 decreased.
- Surface aerosols exert somewhat contribution to low cloud formation.
- Heavy and extreme rain increase sharply since 2003.
- The relation between heavy (extreme) rain and surface aerosols is insignificant.
Aerosol-cloud-precipitation interactions have attracted much more attention for decades, but there still remain many uncertainties in assessing global climate. Long-term ground-based measurements of aerosol, cloud and precipitation in Shanghai were used to examine their inter-annual variations and possible relationships. During 1990–2010, the yearly-averaged total cloud cover (TCC) and low cloud cover (LCC) decrease on average by 0.58% and 2.49% per year. LCC correlates to surface aerosols (e.g., PM10), with a correlation coefficient (R) of 0.67. Aerosol optical depth (AOD), as an indicator of columnar aerosol loading, shows a non-significant correlation with cloud cover. The yearly-aggregated heavy and extreme rain days and their rainfall amount increase gradually. The moderate rain day enhances but its annual rainfall amount declines year by year, while the light rain exhibits an opposite pattern to the moderate rain. These results imply that local aerosols maybe exert somewhat enforcing on low cloud and light rain through possible entrainment or updraft that can bring up surface particles into free troposphere, whereas its influence to total cloud and precipitation is negligible at a small scale. Future studies are needed to ensure whether local aerosols to directly affect low cloud, and to explore how surface aerosols to enter into higher atmospheric layers and impact cloud and precipitation at larger scales.
Rainfall; Aerosol; Cloud cover; Climate change.