Variation Characteristics of Extreme Precipitation in Main Flood Season of Changji Oasis from 1971 to 2020
Based on the daily precipitation data in the main flood season(June-August)from 1971 to 2020 in 7 meteorological stations in Changji prefecture,the daily precipitation was divided into 6 grades.The linear regression and climate tendency rate methods were used to analyze the variation of rainy days,precipitation and extreme precipitation.The results showed that:(1)The number of rainy days in the main flood season in Changji oasis was the highest at Mulei station,with an annual average of 24.26 d,followed by Manasi,which was 20.64 d.The number of rainy days was the least at Hutubi station,only 19.28 d.The spatial distribution of rainy days showed obvious characteristics of less in the north and more in the south,and less in the low altitude area in the north than that in the high altitude area in the south,and the time distribution was unimodal type,with the largest number in July.(2)Except for the increase in Jimusaer station,the number of rainy days in each station showed a decreasing trend.In terms of the proportion of rain days in each magnitude,from light rain to heavy rain,the proportion decreased with the increase of precipitation level.Except for Mulei,light rain had the greatest impact on rainfall,accounting for more than 30%of the six precipitation levels.(3)The contribution rate of drizzle and light rain in the main flood season of Changji oasis was 81.8%,and the contribution rate of precipitation was 33.9%.However,the contribution rate of precipitation times above heavy rain was only 7.3%,and the contribution rate of precipitation reached 40.4%.Therefore,the standard of extreme precipitation was determined as 1 d precipitation≥12.1 mm.(4)The average intensity of extreme precipitation in the main flood season of Changji oasis was 20.1 mm,and the average annual frequency was 1.5 times.The frequency of precipitation showed an increasing trend,and has been in a high incidence period since the 1990s.Extreme precipitation and rainstorm events were mainly concentrated in mid-July,followed by mid-June,and the least in early August.
国家科技期刊平台
NSTL
万方数据
