Study on Spatial-temporal Variation Characteristic of Summer Half Year ETo in Recent 48 Years in Xinjiang
PU Zong-chao,ZHANG Shan-qing(Urumqi Meteorological Bureau of Xinjiang,Urumqi 830001,China)
2011, 32(01):
67-72.
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Based on climatic data of the summer half year(from April to September) of 101 meteorological stations from 1961 to 2008 in Xinjiang,the spatial-temporal variation characteristic of summer half year potential evapotranspiration(ET0) and its climatic cause were analyzed by using the Penman-Monteith equation,linear regression,wavelet analysis,T-test and Kriging spatial interpolation methods in the recent 48 years in Xinjiang.The results showed:(1)the average ET0 in summer half year was 942.5 mm in Xinjiang,but the spatial distribution of ET0 was very obviously different in different regions,generally,the ET0 in the southern Xinjiang was larger than that in the northern,eastern larger than western,basin(valley) larger than the mountain areas.There was significant correlative relation between the spatial distribution of the ET0 and the mean temperature,sunshine hours,precipitation,mean wind speed and relative humidity in the different regions in Xinjiang.In general,the value of ET0 was large in the regions with high temperature,abundant sunshine hours,rare precipitation,lower relative humidity and large wind speed,and vice versa.(2)The correlative analysis showed that there was significantly positive correlation between the summer half year ET0 and the sunshine hours,average wind speed,and significantly negative correlation between the summer half year ET0 and precipitation,average air relative humidity.The correlative dependence was not significant between the summer half year ET0and average temperature,but the annual change tendency between them were consistent.Nearly 48 years,the mean temperature,precipitation and air relative humidity in summer half year were taking on a increasing tendency,and the wind speed was decreasing,but the trend of sunshine hours was not obvious in Xinjiang,in the comprehensive influence of climatic factors,the summer half year ET0 was significantly decreasing by the rate of-20.09mm per 10 years from 1961 to 2008 in Xinjiang.(3) The abrupt examination indicated that the summer half year ET0 had significantly sudden decreases in 1986,and the ET0 after 1986 reduce 65mm than before 1986 by 6.6%.(4)The summer half year ET0 have the cyclical change of 4～5 years,12 years and quasi-22 years.It can be seen from the wavelet transform structure of summer half year ET0,the periodic variation of the various time scales in recent years are in the positive half-period.Therefore,it is expected that the summer half year ET0 will increase in the next few years in Xinjiang.
