On detecting the signature of regional aerosol radiative forcing in eastern China

The Intergovernmental Panel on Climate Change (IPCC) has reported that in southeastern US and eastern China, the greenhouse warming due to man-made gaseous emissions will be dominated by the cooling effect of anthropogenic aerosols. In a recent study, we verified this model prediction in southeastern US by analyzing the trend in daily, maximum, minimum temperatures and daily temperature range during 1949-94 at 52 stations. In this study, we present an analysis of regional patterns of climate change at 72 stations in eastern China during 1951-94 to detect the signal of aerosol radiative forcing. The results support the cooling effect of sulfate aerosols which was evident in the year following the eruption of Mt. Pinatubo. The enhancement in aerosol optical depth was obtained by SAGE II (Stratospheric Aerosol and Gas Experiment) measurement. A decreasing trend in the summer mean maximum temperature during the past 44 years and a one year cooling trend following the Mt. Pinatubo eruption were found. This effect is similar to our finding in the southeastern US. However, a slightly overall warming trend in eastern China is evident; winters have become milder. This finding is explained by hypothesizing that increasing energy usage during the past 44 years has resulted in more coal and bimass burning thus increasing the emission of absorbing soot and organic aerosols. Such emissions in addition to well-known Asia dust may be responsible for the winter warming trend that we have reported here.