基于气温预报的参考作物腾发量预报方法比较

Comparisons of Reference Crop Evapotranspiration Forecasting Methods Based on Temperature Forecasts

为探索精确预报未来短期ET0的方法,比较了4种基于气温预报ET0预报模型,即Hargreaves-Samani（HS）、Thornthwaite（TH）、简化的Penman-Monteith（PT）及McCloud（MC）模型。收集了西藏林芝站2001年1月1日至2013年12月31日的实测逐日气象数据和2012年6月6日至2013年12月31日逐日对未来7d的气象预报数据,在气温预报精度评价的基础上,采用4种基于温度的参考腾发量计算模型直接进行ET0预报,然后采用率定后的模型进行ET0预报,最后与实测气象数据和FAO-56PM公式计算的ET0值进行比较。结果表明,未率定的4种模型预报误差均较大,其中PT公式精度稍高。经率定后,4种公式的预报精度都有所提高,平均准确率为70%,MAE值HS模型最小,平均为0.57mm/d,其他3个模型为1.27～1.50mm/d;RMSE都在2.0mm/d左右;r值总体仍不高,TH模型平均仅有0.19,其他3种模型在0.6左右。综合来看,PT模型的预报效果稳定性优于其他3个模型。对于林芝地区附近的灌区,无论有无气象观测数据供模型率定,建议采用PT模型进行ET0预报。

To explore methods for forecasting short-termET0 precisely,this paper compared four ET0 forecasting models based on temperature forecasts,namely Hargreaves-Samani（HS）,Thornthwaite（TH）,the simplified Penman-Monteith（PT）and McCloud（MC）model.Daily meteorological data for Nyingchi station（Januanry 1,2001-December 31,2013）and daily weather forecasts for7 days ahead（June 6,2012-December 31,2013）were collected.On the basis of temperature forecasts,the original four reference evapotranspiration models,then the calibrated models were employed to forecast ET0,finally the forecast results were compared with the ET0 values calculated from FAO-56 PM model and measured meteorological data.The Results indicated that the four models results considerable forecast errors before calibration,and PT was relatively more accurate than the other three ones.After calibration,the accuracy of forecasting results of four formulas increased significantly,among which the average accuracy rate was70%,HS model had the smallest value of MAE with an average of 0.57 mm/d,for the other three models 1.27～1.50 mm/d;RMSE were about 2.0mm/d;r value were still low overall,with average of 0.19 for the TH model,the other three models around0.6.Generally,the PT model presented stability and was better than the other three models.For irrigation areas near Nyingchi,whether there is meteorological observation data for model calibration or not,using the PT model to forecast ET0 is proposed.