北疆地区生长季参考作物蒸散量的时空变化特征及其敏感性分析

Spatiotemporal Variation and Sensitivity of Reference Crop Evapotranspiration during Growth Season in Northern Xinjiang

基于北疆地区20个气象站点1966-2012年逐日气象数据,采用Penman-Monteith公式计算各站生长季逐日参考作物蒸散量(ET_0),利用线性趋势分析、M-K突变检验、因子贡献率、敏感系数等方法,对该地区ET0的时空变化规律及其对气象要素的敏感性进行分析。结果表明,北疆地区生长季ET_0多年平均值为939.43mm,47a间以16.30mm?10a^(-1)的速率呈极显著下降趋势(P<0.01),并于1981年开始突变。研究区ET_0空间分布具有"平原和盆地多、山区少"的特点;对ET_0变化贡献率最大的因子是平均风速,其次是温度和水汽压,日照时数贡献率最小。北疆地区ET_0对水汽压呈现负敏感,对温度、风速、日照时数呈正敏感,气象因子敏感系数绝对值高低依次为温度>水汽压>风速>日照时数。水汽压升高、风速减小、日照时数减少对ET_0的减小作用超过温度上升对ET0的增大作用,是导致近47a北疆地区ET0总体呈下降趋势的根本原因。

Based on daily meteorological data from 20 meteorological stations from 1966 to 2012, ET0 was calculated during crops growing season by using the Penman-Monteith equation. The spatiotemporal variation of ET0 and its sensitivity to key climatic factors were analyzed by using of the Mann-Kendall test, the factors＇ dedication rate, and sensitive coefficients. The results showed that the average ET0 in Northern Xinjiang was 939.43mm, and the ET0 decreased at the rate of 16.30mm·10y^-1 in last 47 years, with an abrupt change in 1981 according to the Mann-Kendall trend test. Low ETo values occurred in mountain regions, while high values were found in the Junggar basin and piedmont plain. Average wind speed played the most important role with regards to changes in ET0, followed by temperature, vapor pressure, and sunshine hours. ETo was sensitive to vapor pressure negatively, and sensitive to temperature, average wind speed, and sunshine hours positively in Northern Xinjiang. The values of sensitive coefficients to climatic factors were temperature, vapor pressure, wind speed, and sunshine hours. The promoting effect of elevated vapor pressure, less wind speed, and less sunshine hours on ET0 was stronger than the reducing effect of increased temperature, which was the key reason that ET0 decreased generally during crops growth season in Northern Xinjiang.