Analysis On Evolution And Causes Of Aridity-wetness In The Hyperarid Zone Of China From 1960 To 2015

The hyperarid area is the core of arid zones where have sparse vegetation and extensive desert,is the sensitive area in climate change.We should facing the fact that the drought caused by global warming,it is extremely necessary to analyze the characteristics of climate change in the hyperarid area under the extreme background events.China is one of the sensitive regions of global climate change,it has a significant impact on the local climate and the global climate.Analyze the impact of climate change on extreme drought and raise awareness of the laws of climate change in hyperarid area,it is not only beneficial to understand the influence of global warming on regional climate,but also to provide reference for studying the mechanism of landair interaction and the prediction of aridification in hyperarid area,and give some suggestions to improve the ecological environment of hyperarid area.In this paper,the meteorological elements of 51 meteorological stations in hyperarid area are selected and the arid index are calculated as the reference indexes.The meteorological factor inclination rate,continuous wavelet power spectrum,meteorological element abrupt point analysis,extreme precipitation index,meteorological element sensitivity and meteorological element contribution rate were selected to analyze the trend of dry and wet and the change of meteorological factors on hyperarid area of wet and dry from 1960 to 2015.The main conclusions are as follows:The dryness of the hyperarid arid area showed a decreasing trend as a whole,and the wetting trend is significantly than the arid area.There is a significant downward trend in the windward of the Tianshan Mountains,Kunlun mountains,Qilian Mountains and the northern margin of the Tarim basin.There are decreases in the dryness index in different climatic base.The area with a dryness index of less than 16 have trend from increasing to decreasing;the interdecadal have two consecutive peaks to the continuous valley and the area change is the dryness index between 16-30 in the region especially the northern tip of the Tarim Basin,the eastern Qaidam Basin and the Alashan Plateau in 2000 s.The three mutations of the dryness index were monitored,which are 1977,1987 and 2002 that have two trends at 90°E east and west.The turning time of the western and southern sides of the Tarim Basin and the western end of the basin occurred in 1987 at 90°E west.The Piqan,Kumul,Barkol,Hongliuhe,Qakilik and Mangnai,Lenghu,Golmud in Qaidam Basin and Dunhuang,Guazhou,Yumen in the west end of Hexi Corridor occurred in 1977 and the junction of the district was postponed until 2002.In addition,the dryness index continuous wave power spectrum of high energy area also appear east and west two trends.The dryness index showed a significant increase to a significant decline before the 1990 s and the dryness index of 2000 s showed a significant increase in the western.There was a significant decline period before 1990 s,which continued to rise significantly in 2000 s in the eastern.The contribution rate of dryness index trend in hyperarid area precipitation is higher than potential evapotranspiration.The difference between precipitation and potential evapotranspiration is from the highest to the lowest then to the highest.The trend of dryness index is not significantly affected by the potential evapotranspiration,before 2002.The difference between precipitation and the contribution rate of potential evapotranspiration is decreasing,the absolute contribution rate of precipitation is less than the contribution rate of potential evapotranspiration,the stations are increasing,and the effect of the potential evapotranspiration in dryness index is gradually increased.The potential evapotranspiration in dryness index is gradually increased,the relative humidity,the highest air temperature and the change of wind speed play an important effect.The value of potential evapotranspiration is the highest during 1960 from 1976,the value of potential evapotranspiration is decreases during 1977 from 1986.The obviously decreasing time is from 1987 to 2001,the trend of potential evapotranspiration is increasing from 2002 to 2015,especially the eastern of Xinjiang and the western of the Gansu corridor.Under the background of global warming,the meteorological factors sensitivity is changing,the relative humidity sensitivity is decreasing in all study region.The relative humidity sensitivity in the North Tarim Basin is slightly reducing,but the potential evapotranspiration sensitivity of the highest air temperature is increased in the South Tarim Basin and Gansu corridor,especially,the potential evapotranspiration is slightly decreasing due to the increased air temperature.