Evolution Trend Of Drought In Xinjiang Under Climate Change And Its Coping Strategies

Object:In the context of climate change,it is of great significance to study the spatio-temporal evolution and future prediction of drought in Xinjiang for drought monitoring,drought prevention and disaster reduction and disaster warning.Methods:Based on the data of 94 meteorological stations in Xinjiang during 1961-2020,the potential evapotranspiration（ET₀）of Xinjiang was calculated by Penman formula,and the aridity index（AI）was calculated by combining precipitation（P）.The spatio-temporal analysis of temperature,precipitation,ET₀ and AI in Xinjiang was carried out by using climate tendency rate,Mann-Kendall nonparametric test and Kriging interpolation method.Secondly,based on CN05.1 lattice observation data set and ERA5-Land reanalysis data set,7 kinds of CMIP6 model data were downscaled and corrected for deviation,and the multi-model dataset was obtained.Climate change trends and drought evolution characteristics under four different emission scenarios（SSP1-2.6,SSP2-4.5,SSP3-7.0 and SSP5-8.5）during 2021-2050 are projected.Results:（1）Abrupt changes occurred in temperature,precipitation,potential evapotranspiration and AI in Xinjiang around 1994,1986,1971 and 1987,respectively.In recent 60 years,the temperature and precipitation in Xinjiang increased by 0.302℃/10a and 8.58mm/10a,respectively.ET₀ and AI showed a decreasing trend,and the change rates were-14.84mm/10a and-1.94/10a,respectively,indicating that the climate in Xinjiang had a wetting trend.Xinjiang is an arid and semi-arid region.In terms of space,northern Xinjiang has lower temperature,more precipitation,less evapotranspiration and lower AI value than southern Xinjiang in both interannual and seasonal terms.The mountain area has lower temperature,more precipitation and lower AI value than the plain.（2）The mean values and variation trends of temperature and precipitation expressed by the multi-model ensemble average during 1961-2014 are in good agreement with the observed data,which have high reliability for the temperature and precipitation in Xinjiang during 2021-2050 under different scenarios and the subsequent ET₀ and AI predictions.During 2021-2050,the average annual temperature in Xinjiang increased slightly at 0.32℃/10a,0.46℃/10a,0.47℃/10a and 0.67℃/10a,respectively,under four scenarios.The temperature rate of the four seasons shows:autumn>summer>spring>winter.Spatially,under the SSP1-2.6 scenario,the annual average temperature increase rate gradually increases from south to north.Under the SSP2-4.5 scenario,the annual average temperature increases gradually from southwest to northwest.Under the SSP3-7.0scenario,the temperature increase rate in most parts of Xinjiang is between 0.47 and 0.51℃/10a.Under the SSP5-8.5 scenario,the temperature increase rate in most areas of Xinjiang ranges from 0.67℃to0.72℃/10a.With the increase of emission scenario,the average rate of temperature rise of four seasons in the future period will gradually increase.（3）From 2021 to 2050,the change rates of average annual precipitation in Xinjiang under the four SSPs were 3.95mm/10a,1.90mm/10a,2.50mm/10a and 8.67mm/10a,respectively.Under different scenarios,the predicted precipitation growth rate is slowest in winter and faster in spring.Spatially,the precipitation in the whole Xinjiang region showed an increasing trend under the four scenarios.On the whole,except for SSP1-2.6,the increase rate of precipitation in four seasons in the future period will gradually increase with the increase of emission scenario.（4）Under the four SSPs scenarios,the change rates of annual potential evapotranspiration in Xinjiang during 2021-2050 were 15.60mm/10a,22.50mm/10a,23.81mm/10a and 28.99mm/10a,respectively.On the whole,the higher the radiative forcing scenario,the greater the increase rate of seasonal potential evapotranspiration.The increase rate of potential evapotranspiration in four seasons was spring>summer>winter>autumn.In space,under SSP1-2.6 scenario,potential evapotranspiration in the whole Xinjiang showed a decreasing trend.Under the SSP2-4.5 scenario,the potential evapotranspiration increases gradually from southwest to north.Under the SSP3-7.0 scenario,the annual potential evapotranspiration rising speed gradually increases from north to south.Under the SSP5-8.5scenario,the annual potential evapotranspiration in Xinjiang is generally rising at a high rate,ranging from 21.01-52.3mm/10a.（5）During the period from 2021 to 2050,AI showed an insignificant decreasing trend under the four scenarios,and the change rates were-0.31/10a,-0.11/10a,-0.04℃/10a and-0.29℃/10a,respectively.Under different emission scenarios in different seasons,AI trends increased and decreased.In terms of space,AI in Xinjiang showed a decreasing trend under SSP5-8.5 and SSP1-2.6 scenarios,while the decreasing trend was not obvious under SSP2-4.5 and SSP3-7.0 scenarios.From the perspective of seasons,there was no obvious rule of AI in Xinjiang under the four scenarios,which increased and decreased.In conclusion,the climate in Xinjiang will be warm and humid during 2021-2050,and the overall increase rate of temperature,precipitation and potential evapotranspiration will increase with the increase of radiation emissions,while AI will show a weak downward trend.