西藏参考作物蒸发蒸腾量的时空变异规律

根据西藏高原区38个气象站点自建站到2006年的逐日气象观测资料,利用FAO-56标准Penman-Monteith公式计算各站逐日参考作物蒸发蒸腾量(ET₀)。重点分析了7个站点逐日、逐月ET₀年内变化规律,采用Mann-Kendall法对其月际和年际ET₀进行趋势检验;利用Kriging插值及Surfer8.0空间分析功能,得到西藏高原区年ET₀均值的等值线图,分析了全区年ET₀均值的空间分布特征。结果表明:昌都、林芝和那曲的逐日ET₀在年内变化曲线基本一致,呈现单峰抛物线形状,拉萨、泽当和日喀则的逐日ET₀年内变化趋势基本一致,6～9月变化曲线呈现较快的下降趋势,狮泉河的ET₀呈现单独变化趋势;所有站点的逐月ET₀年内变化规律与逐日ET₀相同,最大值均出现在6月份,最小值出现在12月份;日喀则各月及干湿季ET₀的Mann-Kendall检验大多呈现显著的降低趋势,其次是泽当,呈现增加趋势较多的是林芝;全系列年ET₀均值Mann-Kendall检验呈现降低趋势的站点偏多;西藏高原区年ET₀均值具有东部和中南部高,东北部和东南缘低的空间分布规律。

Temporal and spatial variation law of reference crop evapotranspiration in Tibet

Based on the meteorological observation data collected by the 38 weather stations in Tibet for several decades before 2006, the daily values of the reference crop evapotranspiration (ET_0) are calculated by FAO-56 standard Penman-Monteith formula, and the daily and monthly change law of ET_0 over the seven stations is analyzed. The tendency test is conducted on the data of the monthly and annual ET_0 using the Mann-Kendall method. The contour maps of the average annual ET_0 in Tibet are obtained using the Golden Software Surfer 8.0. The spatial distribution of the average annual ET_0 in Tibet is analyzed with the function of spatial analysis. The results indicate that: the daily ET_0 curves of Changdou, Linzhi and Naqu are approximately the same, showing a single peak parabolic shape; and the daily ET_0 curves of Lhasa, Rikaze and Zedang are also approximately the same. The curves from June to September quickly take on the downward trend; ET_0 of the Shiquanhe presents individual change trend. As for all the observation sites, the maximum monthly ET_0 is found in June,and the minimum is in December. In Rikaze, ET_0 mainly shows the decreasing trend each month and in wet and dry seasons very significantly, followed by Zedang. While ET_0 mainly shows the increasing trend in Linzhi. The Mann-Kendall test also indicates that the decreasing in annual ET_0 appears to be the dominate trend in most stations of Tibet. The spatial distribution of average annual ET_0 reveals that the ET_0 values are higher in the eastern and central-southern regions than those in the west and north as well as in the south-eastern fringe in Tibet.