Detection and attribution of extreme precipitation changes from 1961 to 2012 in the Yangtze River Delta in China

Extreme climatic changes frequently have more serious impacts on nature and human society than do changes in the mean value under global climate change. However, extreme climatic events, particularly extreme precipitation, show complex variability because of the effects of natural and human impacts. Taking the Yangtze River Delta (YRD) in China as a case study, the characteristics and trends of extreme daily precipitation events from 1961 to 2012 were investigated in terms of their frequency and intensity. The extreme precipitation events at 30-year and 50-year return periods were analyzed by assuming a generalized Pareto distribution. The detection and attribution of extreme precipitation changes were conducted via the simultaneous evaluation of gradual and abrupt changes. The results indicate a similar pattern of extreme daily precipitation events during different return periods, but the differences in the daily precipitation extremes are quite larger between stations. Thus, regional analyses of different return periods are needed to minimize the risks and losses from extreme precipitation events. We also found reversed trends of extreme daily precipitation events in the YRD when assuming gradual and abrupt changes over the period of 1961-2012. The trend attribution analyses showed that a large-scale monsoon might play a critical role in the intensity and frequency of extreme daily precipitation events in the YRD. However, local factors (e.g., typhoons and urbanization) might play an important role in extreme precipitation changes under a monsoon background.