Accurate estimates of the rain-fed field evapotranspiration (ET) in the Loess Plateau of Northwest China is critical for predicting hydrologic processes, crop yield formation, and climate change. We simulated the ET variation in a rain-fed spring maize field in the eastern Loess Plateau using the Penman-Monteith (PM), Shuttleworth-Wallace (SW), and modified Priestley-Taylor (PT_m) models. Then we compared their results with the observed ET using the eddy covariance (EC) method. Generally, the diurnal variation in estimated ET from the three models was similar to that of observed ET by the EC method. However, the PM model significantly underestimated ET. The ET estimates obtained from the SW and PT_m models were approximately equal to the observed ET by the EC method. Considering the PT_m model’s simplicity, we finally recommend it for rain-fed spring maize fields in the Loess Plateau. After precipitation, the estimated ET from the three models was significantly smaller than measured ET by the EC method, especially the PM model. After a frost, all three models failed to reflect the dramatic decrease in crop transpiration, and thus significantly overestimated ET.

中文翻译：

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黄土高原雨养春玉米三种蒸散模型的比较

对西北黄土高原雨养田蒸散量（ET）的准确估算对于预测水文过程，作物产量形成和气候变化至关重要。我们使用Penman-Monteith（PM），Shuttleworth-Wallace（SW）和改良的Priestley-Taylor（PT _m）模型模拟了黄土高原东部雨养春玉米田的ET变化。然后，我们将它们的结果与使用涡度协方差（EC）方法观察到的ET进行了比较。通常，从这三个模型估算的ET的日变化与通过EC方法观测到的ET的日变化相似。但是，PM模型大大低估了ET。从SW和PT _m模型获得的ET估计值大约等于通过EC方法观察到的ET。考虑PT_考虑到模型的简单性，我们最后将其推荐给黄土高原雨养春玉米田。降水后，这三个模型的估计ET明显小于通过EC方法测得的ET，尤其是PM模型。霜冻后，所有三个模型均未能反映出作物蒸腾作用的急剧下降，因此显着高估了ET。