PNNL

Abstract

Analysis of meteorological data made available by the China Meteorological Administration (CMA) reveals significant decreases in sunshine duration over the latter half of the 20th century over much of China, especially in the eastern half of the country. Most of the decrease has occurred since about 1980, and appears to be related to large increases in atmospheric anthropogenic aerosol loading that have increased the aerosol extinction coefficient (AEC), as calculated from observations of (decreasing) visual range. A finding of particular interest is a significant decrease in summertime maximum temperature over this time period for a large portion of southeastern China near the Sichuan Basin (while the rest of China-and indeed most of the northern hemisphere-has warmed). This same region of southeastern China shows the largest decreases in sunshine duration and largest increases in AEC. The consistent spatial and temporal patterns of change in these variables seem to support the theory that aerosol loading has decreased the duration and intensity of sunshine in this region and thus lowered summertime maximum temperatures.