Substantial Increase in Sub–Daily Precipitation Extremes of Flooding Season Over China

Understanding sub-daily precipitation extremes (SPEs) can provide scientific insights for taking effective measures to mitigate climate risks. Leveraging gauge observations at hourly precipitation in 2,312 meteorological stations and extreme sub-daily precipitation indices (ESPIs), we investigate the changes of SPEs in flooding season of 1971–2022 in China. On country scale, the occurrences and intensity of SPEs have significantly increased and even accelerated since the 21st century, suggesting increases in 2010s by 15%–38% compared with that in 1970s. The SPE risks for 20-year and 50-year return-period increased by 2–4 and 8–20 times in 2001–2022 compared with that in 1971–2000, respectively. Over 80% stations are found to have positive trends in all ESPIs. On regional scale, seven sub-regions experienced significant increases in ESPIs with larger magnitudes in the East China. The enlarged 500-hPa geopotential height, 700-hPa pseudoequivalent potential temperature, 700-hPa specific humidity, saturated vapor pressure and urbanization ratio may be bonded to more SPEs.