Reassessing hourly precipitation–temperature scaling: the diurnal cycle in a warming China

Abstract Hourly extreme precipitation is expected to intensify with global warming following a Clausius–Clapeyron (CC) relationship. While extensive research has investigated the relationship between hourly precipitation and temperature, inconsistencies in this relationship across the diurnal cycle affect all-hours scaling. This study uses hourly gauge observations and reanalysis data from mainland China to analyze the scaling and explore its diurnal cycle for the first time. Our results reveal that 88.7% of the stations exhibit super-CC scaling, which is significantly underestimated by reanalysis data. Notably, the scaling shows a pronounced diurnal cycle and exceeds all-hour scaling, indicating that the mix of precipitation from different hours ultimately affects the overall scaling results. Over a 39 year period, changes in extreme precipitation intensity were closely aligned with dew-point temperatures throughout the diurnal cycle in inland regions. The above results provide a valuable insight into the shift of extreme precipitation to morning/night in some regions under climate change.