Analysis of changes in large-scale circulation patterns driving extreme precipitation events over the central-eastern China

To an extent, large-scale circulation situations and moisture transport are responsible for extreme precipitation occurrence. The aim of our study is to investigate the possible modifications of circulation patterns (CPs) in driving extreme precipitation over the central-eastern China (CEC). The self-organizing map (SOM) and event synchronization methods are used to link the extreme precipitation events with CPs. Results show that 23% of rain gauges have a significant change point (at the 90% confidence level) in annual extreme precipitation from 1960 to 2015. Based on the identified change points, we classified the data into two periods, that is, 1960-1989 and 1990-2015. Overall, CPs characterized by obvious positive anomalies of 500 hPa geopotential height over the Eastern Eurasia continent and negative values over the surrounding oceans are highly synchronized with extreme precipitation events. During 1990-2015, the predominant CPs are more related to the extreme precipitation with enhanced event synchronization. We found that the CP changes produce an increase in extreme precipitation frequency from 1960-1989 to 1990-2015.