FAO Penman-Monteith及简化方法在西北适用性研究

Applicability of FAO Penman-Monteith and Alternative Methods for Estimating Reference Evapotranspiration in Northwest China

为了实现气象资料缺失下参考作物蒸发蒸腾量（ET0）在西北地区的高精度预测，采用FAO 56 Penman—Monteith（P—M）公式作为对照，与气象资料缺失下P—M公式8种情况以及Pristley—Taylor（P—T）法、Makkink 法、Hargreaves—Samani（H—S）法、Irmak法对西北5省区30个辐射站的逐日气象资料进行了统计比较，并对P—T法、Makkink法、H—S法、Irmak法重新进行了参数率定。结果表明，气象资料缺失时，总辐射资料缺失精度下降最小，基于日照资料的ngstrm—Presscott（A—P）法是该地区适宜的替代方法, 其各站平均R2为0.983、RMSE小于0.4mm/d。当相对湿度、风速或日照时数有一项缺失时，使用FAO推荐的P—M替代方法可以使多年平均ET0的RMSE小于0.47mm/d，R2保持在0.94以上。当气象要素缺少风速和相对湿度时，使用率定后Makkink法是该地区适宜的替代选择，其RMSE为0.68mm/d，R2为0.94，当仅有气温资料时，改进后的H—S法是该地区适宜的替代选择，其RMSE为0.68mm/d，R2为0.94。P—T法在该地区精度低于Makkink法，其RMSE为0.71mm/d，R2为0.88，30个站参数值率定后α值介于1.02～1.64之间。

In order to implement the high precision of predicting reference evapotranspiration （ET0） when the meteorological information was not complete in northwest of China, FAO Penman—Monteith （P—M） formula was selected as control, 15 alternative methods were compared in Northwest China, including P—M formula with one to three factors of global solar radiation, sunshine hours duration, relative humidity, wind speed were missing, Pristley—Taylor（P—T）method, Makkink method, Hargreaves—Samani （H—S）method and Irmak method. At last, parameters of P—T method, H—S method, Makkink method and Irmak method were recalibrated. The results showed that global solar radiation data missing had the minimum impact on estimating ET0 with average R2 of 0.983 for all stations and the root mean square error （RMSE） was less than 0.4mm/d. When one of sunshine hour duration, wind speed or relative humidity data was missing, applying the FAO recommended P—M alternative methods could control RMSE within 0.47mm/d, R2 stayed above 0.94. When wind speed and relative humidity data were missing, Makkink method was the best method, the RMSE was 0.68mm/d and R2 was 0.94. When there was only temperature data, the improved Irmak and improved H—S methods had the same precisions with RMSE of 0.63mm/d and 0.68mm/d, the R2 were 0.94 and 0.95, respectively. In addition, the parameters of P—T, Makkink, H—S and Irmak methods were recalibrated for the Kriging interpolation, to obtain the spatial distribution of parameters. The required values of parameters for these methods can be got through the figures.