Characteristics and future projections of summer extreme precipitation in Sichuan Province, China

Based on the precipitation data observed by stations and data simulated by 23 CMIP5 models, the features and future changes of summer (Jun-Jul-Aug) extreme precipitation events in Sichuan Province of China were analysed. We found that the total precipitation (RSum), extreme precipitation threshold (Threshold90), extreme precipitation (TR90), extreme precipitation percentage (TR90pct) and extreme precipitation intensity (TR90str) decreased from the southeast to the northwest in Sichuan Province, reflecting the differences between eastern Sichuan (ESC, basins) and western Sichuan (WSC, mountains). Compared with the observations, most of the CMIP5 models showed that there were wet biases in WSC and an unclear bias pattern in ESC for the RSum, Threshold90, TR90, and TR90str. However, the extreme precipitation days (ND90) and TR90pct values simulated by the models were generally overestimated and underestimated, respectively. Compared with the historical period, most models showed obvious increases in the TR90 and TR90pct in the 21 century, while the characteristics of Rsum, ND90, and TR90str were inconspicuous. Compared with the mid-21st century, the extreme precipitation in the late-21st century exhibited a certain degree of increase. Even during the same period, the results of RCP8.5 were higher than those of RCP4.5, especially for the ND90, TR90, and TR90pct.