| Xinjiang Uygur Autonomous Region is not only the largest province in China,but also the most arid region in China,which has remarkable characteristics of temperate continental arid climate.Due to the influence of natural geographical location and other factors,drought has become one of the most typical natural disasters in northern Xinjiang,which has the characteristics of high frequency of occurrence,wide impact range and large degree of harm,and has a great impact on agriculture,ecology and economy.Quantifying the spatiotemporal variation characteristics of drought in this region is of great significance to predict the future drought trend,reasonably deal with drought events and reduce the loss caused by drought.This study analyzed the temperature and precipitation data of 29 surface meteorological stations in Northern Xinjiang from 1961 to 2017,by calculating the four seasons,the standardization of year scale Precipitation Evaporation Index(SPEI),Combined with Tyson polygon area weighted processing,using linear regression,five point cubic smoothing,Mann Kendall test,Morlet wavelet and Hurst index analysis,the trend change analysis,cycle extraction and trend prediction of spei index are carried out.At the same time,the spatial interpolation of drought frequency was used to map and analyze the spatial range and distribution of drought in Northern Xinjiang.This study has drawn the following conclusions:(1)The variation trend of SPEI index in northern Xinjiang was different in different seasons.It showed a significant increase in winter,indicating that the drought degree in winter was developing towards wetness with a significant trend,while the decrease trend of SPEI index in spring,summer and autumn was not significant,indicating that the drought degree in these three seasons was not significantly tending to drier.On the annual scale,however,there was no significant increase in the SPEI index in northern Xinjiang,and the drought degree showed a slight trend of wetting.The Hurst index results show that in the future,the northern Xinjiang region will continue to dry in spring,summer and autumn,and will continue to wet in winter and annual scale.(2)The results of wavelet analysis show that the first principal period of SPEI index in spring,autumn and winter is 11-year meso-periodic scale,while the first principal period of summer and annual scale is 28-year and 25-26-year long periodic scale.The real part contour map of Morlet wavelet coefficients shows that there is a trend of aridity in spring and autumn of 2021 and 2022.In summer and winter,there is a trend towards wetness.On the annual scale,there is an overall trend towards aridity.(3)The annual probability of drought in northern Xinjiang is more than 70%,of which the local drought is nearly half,the global drought and some regional drought are the second,and the mild and moderate drought are the main ones in each station.From1961 to 1996,the period of drought and drought relief alternated repeatedly,and the whole period was stable.The peak was reached in 1997,followed by 8 years of drought relief.Since 2006,the drought degree and affected area have increased significantly,and the aridity has intensified.In the future,the drought area in Xinjiang has a trend of gradually expanding.(4)The spatial distribution of drought degree shows that the drought grade and frequency near Tacheng,Wusu,bukesail,Altay,Buerjin,Yiwu,Naomaohu,Dabancheng and other stations are high.These stations are the areas with serious drought degree in Northern Xinjiang,and they are also the key areas of drought control,so we should pay attention to drought prediction and prevention in the future. |
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