Climatology and changes in hourly precipitation extremes over China during 1970-2018

Sub-daily precipitation extremes could intensify with temperature at a higher rate than the scaling for daily precipitation extremes, posing increasing risks to natural ecosystem and human society in the era of global warming. A systematic investigation of the climatology and spatiotemporal changes in sub-daily precipitation extremes is of paramount importance to inform future precipitation projection as well as to guide climate adaptation. Here, leveraging a newly proposed set of sub-daily extreme precipitation indices, we examine the climatology and changes in hourly precipitation extremes in mainland China across the major river basins during the warm period of 1970-2018. Our results show that the southern and eastern parts of China tend to experience more frequent hourly precipitation extremes with larger intensity, and the Pearl river basin has the most frequent and intense extreme precipitation at hourly timescale. The Southeast and Yangtze river basins and the mainland China as a whole have field significantly increasing trends in average and extreme precipitation intensities as well as in extreme precipitation frequencies. The intensification signals in hourly precipitation extremes of mainland China seem to emerge from internal climate variability around 2010, whereas average precipitation intensity since 1970 could become field significant earlier than 1999. Besides, we note a marked shift in the probability distributions of the extreme indices, with a wetting tendency toward more frequent and more intense precipitation extremes from the 1970-1999 period to the recent two decades in the 21st century. Our findings provide an alternative line of evidence for changes in precipitation extremes at hourly timescale over China and could contribute to societal decision-making for climate adaptation.