麦田蒸散模型的改进及其对阻力参数的敏感性分析

Evapotranspiration Models for a Winter Wheat Field:the Improvements and Analyses on Their Sensitivities to the Resistance Parameters

采用Penman-Monteith(PM)模型和Shuttleworth-Wallace(SW)模型模拟冬小麦田主要生长季(3-5月)的逐时蒸散量(ET),改进模型中有效叶面积指数(LAIe)的计算,以涡度相关法测定的ET为参照检验模型改进的效果,并分析模型对各阻力参数的敏感性。结果表明:SW模型和PM模型估算的ET均对冠层阻力最敏感。3月小麦冠层稀疏,SW模型模拟ET的效果优于PM模型;4、5月小麦冠层稠密,两个模型模拟ET的效果均较好。改进LAIe计算后,4、5月PM模型和SW模型估算麦田蒸散的精度显著提高,ET模拟值与实测值的相关系数、一致性指数更接近1,ET模拟的相对误差和均方根误差变小。

Penman-Monteith （PM）model and Shuttleworth-Wallace （SW）model were used to simulate hourly evapotranspiration（ET） in a winter wheat field during the main growing season （March-May）. The simulation results were further verified based on eddy flux measurements and the sensitivity of ET simulation to resistance parameters was analyzed. The results showed that ET simulated by PM model and SW model were most sensitive to the change in canopy resistance. Due to the sparse canopy of winter wheat in March, PM model may underestimate ET and SW model was better than PM model in ET simulation Owing to the dense canopy of winter wheat in April and May, both models were satisfied in ET estimation. In April and May, the accuracy of ET simulated by two models was greatly improved by improving the calculation of effective leaf area index （LAIe ）. The correlation coefficient and the index of agreement （IA） for simulated and measured ET were much close to 1, with smaller mean relative error （ MRE ） and root mean square error（RMSE）.