Priestley-Taylor与Penman法计算参照作物腾发量的结果比较

Comparative study on Priestley-Taylor and Penman methods in calculating reference crop evapotranspiration

利用北京气象站 5 0年的气象资料 ,对两种常用的计算参照作物腾发量的公式—— Priestley-Taylor和 Penm an方法的计算结果进行了比较。年值序列比较显示 ,Priestley-Taylor结果远小于 Penm an结果 ,前者比后者低 15 %～ 3 1% ,两者最大相差 3 78.3 mm ,最小相差 15 0 .9mm ,多年平均相差 2 5 5 .9m m。对历年逐月序列分析显示 ,两种方法在 7、8月份的结果十分接近 ,没有显著差异 ,但其它月份均存在显著差异。造成这种显著差异的原因 ,既有降雨的影响 ,又有 Penm an中空气动力学项的影响 ,而后者的影响可能更大些。空气动力项与辐射项之比与两种方法的吻合程度呈显著负相关。该比值越大 ,两种方法的吻合程度越差 ;反之 ,吻合程度越好。

Based on the 50 year meteorological data series of Beijing, the reference crop evapotranspiration calculated with two commonly used methods; Priestley Taylor and Penman methods were compared. Comparison of the yearly results showed that Priestley Taylor method had significant lower value than that of Penman method, with the former being 15%～31% lower than that of the later. The maximum, minimum and multi year average difference is 378.3 mm,150.9 mm, and 255.9 mm, respectively. Comparison of monthly value indicated that the two methods agreed very closely in July and August, in which there was no significant difference. In other months, the difference is significant. The difference is caused by both precipitation and the aerodynamic term in the Penman method, with the later being the main contributor to it. The ratio of aerodynamic term to net radiation is inversely related to the agreement of the two methods. A higher ratio will result in a worse agreement. In contrast, A lower ratio will result in a better agreement.