基于温度资料估算参考作物腾发量的方法比较

Comparative Analysis of Reference Evapotranspiration Estimation Methods Using Temperature Data

以Penman-Monteith方法计算的参考作物腾发量ETo为标准,与采用温度法和辐射法的Penman-Monteith温度法(PMT)、修正的PMT(PMT-cor)、Hargreaves-Samain(HG)、修正的HG公式(HG-M1,HG-M2)、Thornthwaite公式、Irmak公式、修正的Irmak公式(Irmak-cor)、Mc Guinness Bordne公式(M-B)的估算值进行对比分析,同时引入干旱指数对温度法中的PMT公式进行修正,采用多元线性拟合对辐射法中的Irmak公式进行修正。结果表明:温度法中的PMT公式、PMT-cor公式、HG公式和辐射法中Irmak公式、Irmak-cor公式的计算值与PM法计算值间的回归系数b都接近于1.0,相关系数R2大于0.80,相对误差RE小于20%,一致性指数d大于0.95。通过交叉比较发现,Irmak-cor公式精度较高(b=1.00、R2=0.98、RMSE=0.17 mm/d、RE=7%、d=1.00),其次是Irmak公式(b=1.03、R2=0.95、RMSE=0.31 mm/d、RE=12%、d=0.99),再次是PMT、PMT-cor、HG方法。考虑计算结果的精确度,该地区首选Irmak-cor公式估算ETo;如果考虑计算简便,该地区可选HG公式估算ETo。

Accurate estimation of reference evapotranspiration （ETo ） is the basis of irrigation water management. When weather data is lacking or only temperature data is available, ETo has to be estimated with limited weather data. An attempt was made to estimate daily ETo by using temperature-based and radiation-based methods, i. e. , Penman - Monteith temperature method （PMT） , corrected PMT method （PMT-cor）, HG equation, modified HG （HG- M1, HG- M2）, Thornthwaite equation and Irmak equation, corrected Irmak equation （Irmak-cor）, McGuinness Bordne equation （M - B ）. These equations were evaluated against the PM model in Xinxiang. When using the PMT method to estimate ETo, the adjustment of Tmin for estimating Tdow was adopted, when using the Irmak equation, the multiple linear regression was adopted to modify this equation. Results showed that the performance of PMT, PMT-cor, HG, Irmak and Irmak-cor methods were similar, which got the best ETo estimation withcoefficient of regression （b） and determination （R2） around 1.0, relative error RE 〈 20% , index of agreement d 〉 0.95, five models fitted the standard of good model. Cross-comparison of the five good models showed that Irmak-cor equation was the best method which had the highest accuracy in all models with b = 1.00, R2 =0.98, RmsE =0. 17 mm/d, RE =7% , d = 1.00; secondly, the Irmak equation, with b=l.03,R2 =0.95, Rmse=0.31 mm/d, RE=12%, d=0.99. The precision of five models was in turn as Irmak-cor, Irmak, PMT-cor, PMT and HG equation. When considering the precision of the formula, the Irmak-cor equation was the best-suited equation for estimating ETo among the methods, but it was likely more appropriate to use HG equation, due to it was easy to compute and no requirements of temperature adjustment.