| Object:The arid and rainy climatic conditions and fragile ecological environment in Xinjiang make it very sensitive to climate change.In addition,soil wind erosion is the main environmental problem in this area,which seriously threatens agricultural production.Therefore,this thesis aims to explore the spatial and temporal variation characteristics of wind erosion climate erosivity in Xinjiang and the migration law of gravity center,focusing on the response characteristics of wind erosion climate erosivity to climate change in Xinjiang.Methods:Based on the daily meteorological data of 62 meteorological stations in Xinjiang from 1969 to2019,this study uses the methods of climate tendency rate,geostatistical analysis and center of gravity migration to explore the temporal and spatial variation characteristics of wind erosion climatic erosivity,meteorological factors,daily temperature difference and the number of days of wind speed at various levels,and analyze the migration law of center of gravity of wind erosion climatic erosivity.Geographically weighted regression model combined with effective impact area(EIA)was used to quantitatively describe the sensitivity of climatic erosivity to meteorological factors,and the differences of dominant factors affecting climatic erosivity in different regions were analyzed.Cross-wavelet analysis was used to explore the influence of atmospheric circulation on climatic erosivity in Xinjiang.The results are as follows:Results:(1)In the past 50 years,the climatic erosion force of wind erosion in Xinjiang has shown a fluctuating downward trend at the annual and seasonal scales.The climatic erosivity was the highest in spring and the lowest in winter.The minimum value appeared in January and reached the maximum in May.In the past 50 years,the range of extremely heavy erosion areas has been significantly reduced,which is only distributed at the junction of Zhundong area and Tuha Basin and the Alashankou.The eastern Xinjiang,Junggar Basin and its southwestern margin are areas with strong climate erosion activities in spring.The center of gravity of wind erosion climatic erosivity in Xinjiang is distributed in the northwest-southeast direction,mainly distributed in the junction of the north,south and east.In recent 50 years,the center of gravity of wind erosion climate in Xinjiang is mainly distributed in the junction of southern,northern and eastern Xinjiang,and shows the reciprocating migration rule of northwest-southeast-northwest.In the past50 years,the center of gravity of climate erosion force moved 191.15 km eastward and 1°northward.The periodic characteristics of monthly center of gravity change of climatic erosivity are obvious.(2)In the past 50 years,wind speed,relative humidity and DTR showed a fluctuating downward trend,and the decline rates were 0.01 m/(s·a),0.02/a and 0.02°C/a,respectively.The greater the average wind speed and relative humidity,the more obvious the downward trend.The annual average DTR of the whole region fluctuated within the range of 9.4°C～16.4°C.The annual average DTR in the north of the Altun Mountains and the eastern edge of the Taklimakan Desert exceeded 15°C.The DTR in the southeast edge of the Junggar Basin and Turpan Basin decreased significantly.The average temperature and precipitation showed a fluctuating upward trend,and the rising rates were 0.04°C/a and 0.75 mm/a,respectively.The spatial distribution of precipitation showed a zonal distribution.The warming rate is the most obvious in the areas along Tianshan Mountains and the border areas of southern,northern and eastern Xinjiang.The light wind days of 1.6～3.3 m/s accounted for the largest proportion of annual wind speed in Xinjiang,and the strong wind days of>10.8 m/s accounted for the smallest proportion.The daily distribution of wind speed above level 3 in eastern Xinjiang is more,and the wind speed level in northern Xinjiang is mainly2-4.The distribution of 0-2 wind speed days is mostly in southern Xinjiang.(3)Climatic erosivity is the most sensitive to the change of wind speed,and its sensitivity to temperature shows significant north-south differences.Precipitation and relative humidity have inhibitory effects on climatic erosivity.In the past 30 years,the effective influence areas of wind speed,average temperature,relative humidity and precipitation have decreased by 124598.15 km~2,51891.28 km~2,11287.12 km~2and 18627.12 km~2,respectively.The climate erosivity in Hotan and Kashgar is most sensitive to the change of diurnal temperature range.In the past 50 years,the effective influence area of DTR on climatic erosivity increased by 120815.44 km~2.The wind speed of 10.8-13.8 m/s has the greatest impact on the wind erosion climatic erosivity.(4)The average C-factor value was weaker during El Ni(?)o events and stronger during La Ni(?)a events,which implies that the climatic erosivity was controlled by large-scale atmospheric circulations.The influence of El Ni(?)o events on climatic erosivity in Xinjiang could be sustained from the beginning of the events to two months after the end of the events.The La Ni(?)a events had a lag effect on the climatic erosivity in Xinjiang,with a lag period of 4 months.ENSO and climatic erosivity show a strong coherent period of 8～12 years in the low energy region and ENSO changes advance 1/4 cycles of climatic erosivity.NAO and climatic erosivity show the same correlation in distinct bands.There is a resonance period of12-16 years between AO and climatic erosivity,and the change of AO precedes 1/8-1/4 cycles of climatic erosivity. |
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