Seminar on Physics and Chemistry of the Atmosphere (Abstract)

Possible influence of the anthropogenic SO2 emission on low-level cloud properties over China
 

 
Indirect effect by anthropogenic aerosols, that is, cloud modification caused by human activity, is one of the most uncertain factors among climate issues, as IPCC reports indicate. Since early 1980s, the energy consumption in China had increased substantially due to an economic development caused by the drastic political changeover. Under this background, the effect of human activity on low-level cloud properties (the particle size, optical depth and particle number) was explored using SO2 emission as a proxy. The cloud properties were derived from optical remote sensing using satellite sensors. As a result of comparison between annual-mean SO2 emission and cloud properties, the cloud particle size becomes smaller, on the other hand, the cloud optical depth and particle number get larger, as SO2 emission increases. These behaviors can be explained by Twomey effect due to linkage from SO2 to aerosols. Multiyear comparison between 1985 and 1995 suggests reduction of the cloud particle size and enhancement of the cloud optical depth and particle number in accordance with an increase in SO2 emission. The results obtained here would give evidence in large-scale cloud modification by anthropogenic activity over land, which was thought to be less sensitive compared to over ocean.