Characteristics of Summer Hourly Extreme Rainfall Events in the Region of Southeastern Xizang Plateau-Western Sichuan Basin

Based on 109 hourly rain-gauge stations from June to August during 2005 -2020， the spatial and temporal distribution of annual rainfall amount， occurrence， rainfall intensity， and duration of summer hourly extreme rainfall events in the region of Southeastern Xizang Plateau-Western Sichuan Basin （28°N -33°N， 90°E - 105°E） are analyzed.Additionally， the diurnal variation of rainfall amount， rainfall intensity， and rainfall frequency during hourly extreme rainfall events in the region of Southeastern Xizang Plateau-Western Sichuan Basin are also explored.Results show that the hourly extreme the rainfall threshold， the annual rainfall amount， the rainfall intensity， and the duration of summer hourly extreme rainfall events in the region of Southeastern Xizang Plateau are lower than those in the region of Western Sichuan Basin， with the occurrence showing the opposite pattern.The annual rainfall amount and occurrence， and duration of summer hourly extreme rainfall events in the region of Southeastern Xizang Plateau increase over time.The annual rainfall amount and occurrence of hourly extreme rainfall events in the region of Western Sichuan Basin also increase， while the duration of hourly extreme rainfall events in the region of Western Sichuan Basin change insignificant.The rainfall amount’， the rainfall intensity’ and the rainfall frequency’ peak time of the summer hourly extreme rainfall events in the region of Southeastern Xizang Plateau -Western Sichuan Basin exhibit the eastward delayed features， and their peak time in the region of Western Sichuan Basin are 3 h， 4 h and 2 h later than those in the region of Southeastern Xizang Plateau， respectively.The most evident delayed feature exists in the rainfall intensity in June， with the peak time in the region of Western Sichuan Basin being 11 hours later than that in the region of Southeastern Xizang Plateau.However， both the Southeastern Xizang Plateau and Western Sichuan Basin regions exhibit insignificant interannual variation in the peak time of the rainfall amount， the rainfall intensity， and the rainfall frequency during summer hourly extreme rainfall events.