Identification And Evolution Characteristic Analysis Of Flash Drought In Northern Xinjiang Based On SPEI Index

Based on the meteorological data of temperature and precipitation from 1961 to 2020,this paper analyzes the historical drought and historical drought in Xinjiang based on SPEI,and explores the temporal evolution laws of the intensity and frequency of meteorological drought in northern Xinjiang under SPEI at different time scales.By combining the identification criteria of flash drought at home and abroad with the unique situation of northern Xinjiang,an effective identification criteria of flash drought in northern Xinjiang is determined,and the spatial and temporal evolution characteristics of flash drought are explored.Then the occurrence and evolution characteristics of the CMIP6 until 2100.The main achievements achieved are as follows:(1)The SPEI can better characterize the typical drought years in northern Xinjiang.The climate in northern Xinjiang showed a more humid trend from 1961 to 2020,but the climate in spring and summer showed a more arid trend.The results of EOF analysis show that there are mainly two spatial modes of meteorological drought change in northern Xinjiang,among which the variance of the first mode contributes to 62.1%,which is mainly manifested as spatial consistent type,and the oscillation intensity gradually increases from southwest and southeast to northeast.(2)Although the climate of northern Xinjiang has shown a warming and humidification trend in the past 60 a,the coverage(station ratio)and severity(duration)of sudden drought have shown different degrees of upward trend,indicating that in the future,northern Xinjiang will face more risks from sudden drought,and in 2008,the highest coverage(92% of sites)and the longest sudden drought in history occurred.The analysis of the frequency and occurrence of sudden drought in northern Xinjiang,the number of weather,frequency,and the proportion of drought shows that the probability of drought in northern Xinjiang fluctuates around 50%,and the region with the greatest probability of drought is in the western part of northern Xinjiang,while the region with the greatest probability of sudden drought is in the east.In terms of the proportion of sudden drought in drought,in the nearly 60 a time in northern Xinjiang,the Eastern Beitashan region is the area with the largest proportion of drought in sudden drought,which means that once drought occurs in these areas,the likelihood of sudden drought is higher than that of other regions,thus causing serious harm to local agriculture.(3)Under the SSP1.26 and SSP5.85 modes,the coverage and duration of future flash droughts in northern Xinjiang have different degrees of growth trend;the coverage of flash droughts in the SSP2.45 mode shows a slow downward trend,but its duration also shows an upward trend,and the frequency and total duration of flash droughts in the three modes show a pattern of high in the southwest and northeast and low in the central region.Under the SSP1.26 model,the number of flash droughts can be roughly divided into the area with an increase in the number of flash droughts east of the Karamay-Ussu line and a decrease in the number of times west of the line,and the average duration of flash droughts can be roughly divided into the average duration increase area west of the Habahe-Ulan-Usu line and the average duration reduction area east of the line.Under the SSP2.45 model,the number of flash droughts in northern Xinjiang can be roughly divided into the area with an increase in the number of flash droughts in the southwest of the Tacheng-Qitai line and a decrease in the number of droughts in the northeast of the line;the average duration of flash droughts can be roughly divided into the average duration increase area of Burzin and Altay and the average duration increase area except for the area around Burzin and Altay.Under the SSP5.85 model,in terms of the number of flash droughts,the number of flash droughts in northern Xinjiang will increase to varying degrees except for the areas near Altay,Burzin and Habahe;in terms of the average duration of flash droughts,northern Xinjiang can be roughly divided into the average duration increase areas near Altay,Burzin and Urumqi and the average duration reduction areas other than these areas.