Probability distribution characteristics of summer extreme precipitation in Xinjiang, China during 1970-2021

Abstract Based on the daily precipitation data of 96 stations in Xinjiang from 1970 to 2021, the Generalized Extreme Value (GEV) model was used to investigate the fitting effect of stationary and non-stationary GEV models on summer extreme precipitation series in Xinjiang. The time trend of extreme precipitation in summer and the difference of probability distribution of extreme precipitation in South and North Xinjiang were analyzed. The results show that: (1) In North and South Xinjiang, the averaged PRCPTOT (The summer total precipitation) at most stations were between 20–50 mm and exceeded 50 mm in the past 50 years, respectively. The RX1day (maximum 1-days precipitation) and RX5day ( maximum 5-days precipitation) at most stations in Xinjiang showed a an increasing trend, while the summer CDD (consecutive dry day) at most stations in Xinjiang showed a decreasing trend. (2) The increase of return period, the confidence interval (uncertainty) of the return level of each extreme precipitation induces increases. The average intensity of RX1day and RX5day at stations in North Xinjiang are greater than at stations in South Xinjiang. The average intensity and inter-annual variability of CDD at stations in South Xinjiang are greater than at stations in North Xinjiang. (3) The RL20 (20-year return level) of RX1day and RX5day at most stations are 25 ~ 40 mm and 30 ~ 60 mm respectively except central region of Xinjiang. However, the RL20 of CDD at most stations in South Xinjiang exceeded 40 days, and experienced 30 ~ 50 days in North Xinjiang.