新疆艾比湖绿洲干燥指数变化特征

Change of Aridity Index in the Ebinur Lake Oasis,Xinjiang

基于艾比湖绿洲4个气象站1960-2013年逐月的气候资料,计算了干燥指数。结果表明:(1)艾比湖绿洲近54 a干燥指数的均值为6.97,属于干旱地区,干燥指数呈显著下降趋势,并且持续性较强,下降幅度约为0.49·(10a)^-1(P<0.05);夏季的干燥指数最大,为9.04,冬季最小,仅为2.20。(2)艾比湖绿洲全年干燥指数在1985年发生突变性减小,夏季和冬季发生突变性减小的年份为1991年和1983年,而春季和秋季不存在突变点。(3)艾比湖绿洲干燥指数的演变过程存在着7~8 a和20~21 a的周期变化,其变化的第一主周期为9 a,第二、三周期分别为21 a和5 a。(4)干燥指数对于风速的变化最为敏感,并且相对贡献率最高,而日照时数的变化最不敏感。

In this paper,the values of annual and seasonal aridity index in the Ebinur Lake Oasis in Xinjiang,China were calculated based on the measured data of monthly precipitation,wind speed,relative humidity and radiation at four meteorological stations in the oasis during the period from1960 to 2013.The linear fitting method,MannKendall mutation test,wavelet analysis and climate sensitivity coefficient test were used.The results are as follows:(1)The average aridity index of the Ebinur Lake Oasis was 6.97 in recent 54 years,and it suggested that the study area could be categorized as an arid region.The aridity index was in a significant decrease trend with an average rate of 0.49·(10 a)^-1(P<0.05).The average aridity index in summer was as high as 9.04,but its minimum value in winter was 2.20 only;(2)The annual aridity index in the Ebinur Lake Oasis was sharply decreased in 1985.Seasonally,the sharp decrease of aridity index in summer and winter occurred in 1991 and 1983 respectively,however,there was no mutation of aridity index in spring and autumn;(3)There were 7-8-year and 20-21-year periodic variations of aridity index in the Ebinur Lake Oasis in recent 54 years,the first principal period of aridity index variation was for 9 years,and the second and third periodical changes were for 21 years and 5 years respectively;(4)The aridity index in the Ebinur Lake Oasis was the most sensitive to the change of wind speed,the contribution of wind speed change to the variation of aridity index was the highest,and the aridity index was not sensitive to the change of sunshine duration.