Spatial and Temporal Distribution Characteristics of Precipitation Days in Qaidam Basin
Based on the daily precipitation data of 10 meteorological observation stations in Qaidam Basin for a total of 63 years from 1961 to 2023,the temporal and spatial distribution of precipitation days of different grades in Qaidam Basin was analyzed by meteorological statistical analysis methods such as climatic propensity rate method,Mann-Kendall method,Morlet wavelet transform and empirical orthogonal function(EOF)analysis.The results showed that:(1)The peak numbers of days of light,moderate and heavy rainfall in the Qaidam Basin occurred in July,and the peak number of days of rainstorm was in August.No extremely heavy rainstorms or catastrophic rainstorms had been recorded.(2)The annual number of days of light rainfall in the Qaidam Basin showed an obvious decreasing trend over time,while the annual number of days of medium and heavy rainfall showed a significant increasing trend.(3)The abrupt changes in the annual number of days of light rain,medium rain and heavy rain in the Qaidam Basin occurred in 2011,1993 and 2007,respectively.(4)The main periods of the annual number of days of light rain,moderate rain and heavy rain were 22 years,10 years and 20 years,respectively.(5)The first mode of the annual number of days of light rain showed a consistent spatial pattern across the region,while the second mode showed an east-west anti-phase pattern.For moderate rain,the first mode showed an east-west anti-phase feature,and the second mode showed the feature of more days in central-eastern region and fewer days in other regions.For heavy rain,the first mode indicated the pattern of more days in central-eastern region and fewer days in other regions,and the second mode showed a consistent feature across the region,while the third mode showed an east-west anti-phase feature.
Qaidam BasinClimatic propensity rateMorlet wavelet transformEmpirical orthogonal function
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