Daytime-and-nighttime-precipitation-unevenness

Both models and observations show that precipitation unevenness has systematically amplified globally. However, trends in subdaily precipitation unevenness and the contribution of extreme precipitation to unevenness remain unclear. Using satellite precipitation data from 2001 to 2022, we found that precipitation unevenness, quantified by the unevenness index (UI), exhibits a significant increasing trend at subdaily timescale, despite regional variations. Extreme precipitation events (the upper 2.5%) account for approximately one-third of precipitation unevenness. Both the mean contribution and the upward trend of the contribution of extreme events to nighttime precipitation (34.75%, 0.27%·yr-1) exceed that to daytime (32.82%, 0.21%·yr-1). These insights highlight the widespread increase in subdaily precipitation unevenness during both daytime and nighttime, with extreme precipitation playing a disproportionately large role, particularly at night.