河西地区近50年参考作物蒸散量的演变趋势及其影响因素

根据河西地区17站点近50年的逐日气象资料,利用Penman-Monteith方程计算了逐日ET0,以Mann-Kendall法对各站不同季节、年ET0平均总量进行趋势检验。结果表明：武威、古浪、天祝3站年ET0呈增加趋势,其余14站均呈下降趋势,其中有9站通过显著性水平检验。春、夏、秋、冬四季酒泉地区和张掖地区各站ET0值均呈下降趋势,武威地区各站变化趋势不一致,且前者ET0值下降趋势总体较后者明显。典型站点ET0与气候要素多元线形回归分析表明：风速是不同季节、不同站点影响ET0变化的首要因子。其次,最高温度、相对湿度、日照时数也是影响年ET0及各站点不同季节ET0变化的主要因子。

Analysis of the change trend and effect factors of reference crop evapotranspiration in recent 50 years in Hexi region

Based on the daily meteorological data collected from seventeen meteorological stations in recent 50 years in Hexi region,daily reference evapotranspiration（ET0）was calculated by using the FAO Penman-Monteith equation,and Mann-Kendall method was used to test seasonal and yearly ET0 series of all stations.The results showed that the annual ET0 of Wuwei,Gulang and Tianzhu stations indicated increasing trend,however,the others 14 stations declined in which 9 stations reached the significance level（α=0.05）.The ET0 of the stations in Zhangye and Jiuquan regions in spring,summer,autumn and winter decreased.Variations of ET0 were inconsistent in the stations of Wuwei region.Compared with the latter,a downward trend was obvious in former.Multiple linear regression analysis between ET0 and climate factors at typical stations showed that wind speed was the primary factor affecting ET0 in different seasons and different sites.Second,the maximum temperature,relative humidity and sunshine hours also affect the annual and seasonal ET0 changes in different stations.