夏玉米蒸散优化参数模型及参数敏感性分析

分别采用2种不同的冠层阻力模型和土壤阻力模型,组合成4种Shuttleworth-Wallace(S-W)模型,模拟夏玉米农田灌浆期的逐时蒸散量,以涡度相关法观测蒸散量为实测值检验模型改进的效果,找出最优冠层阻力模型和土壤阻力模型,并分析最优S-W模型对各阻力参数的敏感性。结果表明:李俊改进型有效叶面积指数冠层阻力模型和Sellers土壤阻力模型组合的S-W模型模拟效果最好,S-W模型估算玉米田蒸散的精度显著提高,蒸散发模拟值与实测值的相关系数、一致性指数更接近1,蒸散发模拟的相对误差和均方根误差变小。敏感性分析表明,在计算各个阻力参数模型中,S-W1模型估算蒸散发对冠层阻力最敏感,其次是土壤阻力和有效叶面积指数;采用改进型有效叶面积指数冠层阻力模型和Sellers土壤阻力参数模型组合后,在一定程度上提高了模型精度,提高了计算准确率。

Improvement of evapotranspiration models in summer maize field and its sensitivities analysis to the resistance parameters

Four Shuttleworth-Wallace (S-W) models were used to simulate hourly evapotranspiration (ET) in the grain filling stage of summer maize by different canopy resistance models and soil surface resistance model. In order to determine the optimum model of canopy resistance and soil surface resistance, the effect of the improved model was measured by eddy correlation method of evapotranspiration. The sensitivity of the optimal resistance parameters was also analyzed. The results showed thatthe improved S-W model had the best simulation results. After S-W model was improved, the accuracy of estimation of maize field evapotranspiration was significantly improved. The correlation coefficient and the consistency index of ET simulated and measured values were close to 1, and the relative error and root mean square error of ET simulation became smaller. Sensitivity analysis showed that the canopy resistance was the most sensitive parameter, the second was the soil surface resistance, and the third was the effective leaf area index. To a certain degree, the model precision was improved by using the improved effective leaf area index canopy resistance model and the soil surface resistance model, which can improve the accuracy of the model calculation.