Variations and comparisons in hourly and daily precipitation extremes over eastern China in recent warming periods

Under global warming, a notable intensification of precipitation extremes has posed significant threats to both natural ecosystems and human societies. However, there is still a lack of systematic studies on the variability of hourly precipitation extremes and a comparison with daily precipitation extremes. This study introduces a set of indices for hourly and daily precipitation extremes to systematically examine the changes across eastern China during the summers from 1980 to 2020. The results show that southern China is the sensitive regions with a notable large value of climatology in frequency and intensity for both of hourly and daily precipitation extremes. For the trends, the frequency of hourly precipitation extremes shows a rising trend in southern China, and intensity increased in northern China. Conversely, for daily precipitation extremes, the enhanced intensity and frequency are observed only in southeastern China. Additionally, the eastern coastal area experiences prolonged hourly rainfall with increasing persistence, while the region with an increased duration of daily precipitation is situated further south. Comparing the periods 1980–1999 and 2000–2020, precipitation extremes shift toward more intense and more frequent, with more pronounced variations at the hourly scale. Notably, northeastern China tend to be more intense and shorter-lived hourly precipitation extremes after 1999, while south China experiences more frequent and longer-lasting extremes. These changes are partly attributed to the increased unstable conditions, enhanced convective available potential energy and weakened convective inhibition.