新疆气候干湿变化特征及其影响因素

Climate dry-wet conditions,changes,and their driving factors in Xinjiang

基于新疆56个气象站1961—2019年逐日地面观测数据,分析了过去59 a间新疆干湿变化特征及其成因,主要结论如下:(1)新疆正经历显著的由干向湿的转变。在1961—2019年期间,区域平均干燥度指数(Aridity In⁃dex,AI)以0.01·(10a)^(-1)的速率上升(P<0.01),并于1987年前后发生突变。全区呈显著上升趋势的站点占比为57.1%。(2)1961—2019年间新疆年降水量以8.6 mm·(10a)^(-1)的速率显著增加,突变时间与AI突变时间一致。年参考作物蒸散量(reference evapotranspiration,ET0)在1961—2019年可检测到显著的下降趋势,变化速率为-15.7 mm·(10a)^(-1)。但值得注意的是,年ET0在1990年前后发生转变,1990年以前持续下降,1990年后转为波动上升。(3)ET0的变化主要受风速与相对湿度两种气候因子的控制。在1961—2019年间,全区风速基本呈下降趋势,有接近一半站点的相对湿度也呈下降趋势,二者的共同作用导致新疆50%站点的ET0显著下降。而ET0在1990年前后的转变也是由于相对湿度和风速变化趋势在1990年前后的转变引起的。1990年左右,相对湿度由上升趋势转为下降趋势,风速则由下降趋势转为上升趋势。共同导致了ET0在两个时期变化趋势的差别。该结论加深了对新疆干湿变化及其成因的认识,并对新疆水资源的合理开发利用具有一定参考价值。

Based on daily observations from 56 meteorological stations from 1961 to 2019,this study analyzed dry-wet conditions,changes,and their underlying driving factors in Xinjiang.The main findings are as follows:(1)In the past 59 years,the Xinjiang climate has changed significantly from dry to wet,with the aridity index(AI)changing at a rate of 0.01·(10a)^(-1)(P<0.01).The number of stations with a significant upward trend of AI accounted for 57.1%.(2)The annual precipitation in Xinjiang increased significantly at a rate of 8.6 mm·(10a)^(-1)from 1961 to 2019,consistent with the change in AI.Conversely,the annual reference evapotranspiration(ET0)showed a significant decreasing trend at a rate of-15.7 mm·(10a)^(-1).However,it is worth noting that ET0 transitioned around 1990.ET0 continued to decrease before 1990 and then switched to a fluctuating upward trend.(3)Wind speed and relative humidity primarily influenced ET0 variation.Wind speed exhibited a consistent decreasing trend across the entire region,while approximately half of the stations observed a decline in relative humidity.The combined effect of these factors significantly decreased ET0 at nearly 50%of the stations in Xinjiang.Moreover,trends in relative humidity from increasing to decreasing trends and wind speed from decreasing to increasing around 1990 contribute to the differences in ET0 trends between the two periods.The conclusions achieved here provide valuable insights into understanding the dry-wet changes and their underlying driving factors in Xinjiang and have implications for the rational development and use of water resources in this region.