Spatiotemporal variations in extreme precipitation and their potential driving factors in non-monsoon regions of China during 1961-2017

Extreme precipitation events affect the ecological environment and are also important for the sustainable development of regional socioeconomics. Although there are some local studies on extreme precipitation events in which the temporal and spatial variation characteristics of extreme precipitation events in non-monsoon regions (NMRs) are systematically assessed, detailed study on the driving mechanisms of variation are becoming increasingly important. In this study, nine extreme precipitation indices were used to analyze the characteristics of extreme precipitation event spatiotemporal variations in NMRs in China during 1961-2017. The results show that except for the consecutive dry days, which shows a significant decreasing trend (P < 0.01) of -2.33 days/decade, all other indices showed obvious increasing trends, especially the indices of wet day precipitation (PRCPTOT), highest 5 day precipitation (RX5day) and light rain days (R5mm), with significantly increasing trends (P < 0.01) of 6.80mm/decade, 0.73 mm/decade and 0.45 days/decade, respectively. In addition, a correlation analysis between altitude, longitude, latitude and extreme precipitation shows that stations at an altitude of more than 3500 m have significant correlations with both extreme precipitation and longitude in NMRs (P < 0.05). In addition, results also indicated that there are significant relationships between extreme precipitation events in NMRs and large-scale ocean-atmosphere circulation patterns (P < 0.05). The rapid increase in extreme precipitation indices over the past 20 years is closely related to the Atlantic Multidecadal Oscillation shift to a warm phase, while the Pacific Decadal Oscillation, El Nino-Southern Oscillation and Summer Monsoon Index show significant correlation with the extreme indices only in certain seasons (P < 0.05).