四川冬春季参考作物蒸散量时空变化及其成因

为深入认识四川冬春季参考作物蒸散量(ET₀)的变化特征,利用1980—2016年四川35个气象站的逐日气象观测资料,采用泰森多边形、气候倾向率和克里金空间插值等方法对其冬春季ET₀的时空变化特征进行分析,并通过敏感性和贡献率分析了ET₀的变化成因。结果表明:ET₀的年代际变化呈先降后增的趋势,空间上呈明显的西南高东部低的分布特征,且高值区范围持续扩大,低值区范围波动缩小。ET₀的年际变化呈上升趋势,春季ET₀气候倾向率和空间差异明显大于冬季,且ET₀高值区与低值区空间分布受海拔高度影响明显。ET₀的同一日多年平均值自初冬至初春逐渐上升,1月22日—5月2日仅有8 d的ET₀值低于多年日平均值,具有明显连续的高值时段。ET₀对日照时数的变化最敏感,其次是对相对湿度与平均气温,对三者均呈高敏感性。平均气温的正贡献率是引起ET₀变化的主导因子,其次是相对湿度。研究时段内平均气温的升高对ET₀的正效应和相对湿度的降低对ET₀的负效应,超过了日照时数减少对ET₀的减少效应,导致四川地区冬春季ET₀呈上升趋势。

Spatio-temporal changes and causes of winter and spring reference crop evapotranspiration in Sichuan

To make a better understanding of the variation characteristics of reference crop evapotranspiration (ET₀) in winter and spring in Sichuan Province, based on the daily observed data of 35 meteorological stations in Sichuan from 1980 to 2016, the spatio-temporal changes of ET₀ in winter and spring in Sichuan were analyzed with Thiessen polygon, climate change rate and Kriging spatial interpolation method. Then, the sensitivity coefficients were combined with the contribution rate to study the causes of ET₀ changes. The results showed that the interdecadal variation of ET₀ firstly decreased and then increased. The distribution was obviously high in the southwest and low in the east, and the range of the high value area continued to expand, while the range of the low value area narrowed down in fluctuation. The interannual variation of ET₀ showed an upward trend. The climate change rate and spatial difference of ET₀ in spring were greater than that in winter, and the distribution of the high value area and the low value area of ET₀ was affected by the altitude. The multi-year mean value of the same day ET₀ increased gradually from early winter to early spring. During January 22 to May 2, there was an obvious continuous period of high value, in which the ET₀ value lower than the multi-year daily mean value appeared only in 8 d from 1980 to 2016. Sunshine hours showed positive sensitive coefficient, which was also the most sensitive variable, followed by relative humidity and mean temperature. Temperature was the main factor that affected ET₀ change with the largest contribution rate, which was followed by relative humidity. The positive effects caused by the increasing trend in mean temperature and the negative effects caused by the decreasing trend in relative humidity on ET₀ exceeded the effects caused by the decreasing sunshine hours, which resulted in the ET₀ rise in winter and spring in Sichuan.