| Summary: | A regional climate model (RegCM4.1) is used to conduct two sets of sensitivity experiments. There are 20-year runs in each set of experiments. The experiments in each set include the variation of anthropogenic SO _2 emissions during 1989–2008 but exclude natural variations of the atmosphere and sea surface temperature. The model results suggest that the high-speed emission of SO _2 and its uneven distribution over eastern China can contribute to the change in May–August rainfall over eastern China between the two decades of 1999–2008 and 1989–1998, especially to the decrease (increase) of rainfall in the Yangtze River valley (Huang-Huai River region). Furthermore, the areas of decreasing (increasing) rainfall correspond to the downward (upward) currents of the anomalous atmospheric circulation, which is caused by the two humps of the difference in sulfate concentration between the two decades.
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