Study On The Change Of Potential Evapotranspiration In The Urumqi River Basin In Recent 50 Years Under Climate Change

Evapotranspiration is an important process of water circulation,and it is the link between energy balance and energy,which plays an important role in surface energy.The facts of global and regional warming have been widely recognized by most international scholars.The increase in temperature will cause an increase in evapotranspiration,but under the global warming trend,the global potential evapotranspiration is decreasing.Global change has a significant impact on water cycle.In desert ecosystems,precipitation is the main source of water cycle,and evapotranspiration is the main output of water cycle.The characteristics and laws of precipitation and potential evapotranspiration in the study area will further deepen the relationship between regional vegetation and water in the context of global change.Under the general trend of warming and humidification in Xinjiang,the climatic conditions in the Urumqi River Basin are also changing.Therefore,Accurate estimation of potential evapotranspiration in this area and analysis of its changing trend are of great significance for understanding the regional water cycle and scientific management of water resources.This paper analyzes the climatic factors and potential evapotranspiration of various climatic zones in the Urumqi River Basin from 1964 to 2015,and analyzes the sensitivity of various climatic factors affecting potential evapotranspiration.The conclusions are as follows:(1)Urumqi River Basin and each The overall climatic zone climate is warm and humid,and the average sunshine hours and average wind speed are both decreasing.The average relative humidity is increasing except for the mountain grassland belt and the mountain desert belt.The spatial distribution of climatic factors varies.The average temperature and sunshine hours are spatially distributed.The northern region is larger than the southern region.The precipitation and average wind speed are larger in the southern region than in the northern region.The average relative humidity in the northwest region is larger than that in the southeast region.(2)The potential evapotranspiration of the Urumqi River Basin from 1964 to 2015was 875.59 mm,and the annual potential evapotranspiration showed a significant decrease trend at a rate of 23.94 mm per 10 years.The climatic zone has a decreasing trend except for the annual average ET₀of the alpine meadow belt.In the alpine meadow belt,an augmentation mutation occurred in 2006,and other mutations occurred in each of the bands.In terms of spatial distribution,spatial differences are obvious,and can be divided into high-value areas(mountain forest belt and mountain desert belt centered on Urumqi)and low-value areas(alpine meadow belt and mountain steppe belt in the south).(3)The Urumqi River Basin and each climatic zone are most sensitive to relative humidity,and are inversely affected.The value and rate of change of ET₀decrease with the increase of relative humidity,with average wind speed,average temperature and maximum temperature.Increase and increase.(4)The Urumqi River Basin and each climatic zone are significantly positively correlated with the average wind speed and sunshine hours,and the correlation with the average wind speed is the most significant,and it is significantly negatively correlated with relative humidity and precipitation,and the average temperature is Significantly positive correlation.The correlation coefficient of each climatic zone is slightly different.In terms of contribution rate,the annual variation rate of the Urumqi River Basin and each climatic zone is the highest,and the contribution rate of the annual climatic factors in each climatic zone is slightly different.Although the sensitivity coefficient of relative humidity is the largest in the Urumqi River Basin and each climatic zone,its own trend of change is the smallest;although the wind speed sensitivity coefficient is less than the relative humidity,the trend of its own change is the most significant,which makes the average wind speed contribute the most to ET₀.