利用小蒸发皿观测资料确定参考作物蒸散量方法研究

参考作物蒸散量是土壤－植被－大气系统水分能量平衡模型的重要参数，如何准确获得将直接影响模型应用和最终模拟预测精度。该文利用分布于黄土高原地区65个气象站1971～2000年的气象资料，以FAO推荐的Penman-Monteith方法确定的参考作物蒸散量为标准，提出了根据平均相对湿度与风速为变量确定由20 cm小蒸发皿观测的水面蒸发量计算参考作物蒸散量的系数Kp。结果表明：由蒸发皿观测值计算的3 d或更长尺度的ET₀与Penman-Monteith方法计算的ET₀结果一致性很高，在对Kp方程系数进行适当的地域性调整后，由蒸发皿观测值和Kp确定的ET₀与Penman-Monteith方法确定的ET₀结果一致，从而认为在黄土高原地区参考作物蒸散量计算可以应用20 cm蒸发皿系数法。

Estimation of reference crop evapotranspiration by Chinese pan

The reference crop evapotranspiration is a key parameter for soil-plantation-atmosphere transfer system models, which influence the application of models and the precision of prediction. The 20 cm Chinese pan coefficient Kp was presented according to meteorological data from 65 climatic stations in the Loess Plateau from 1971 to 2000 and the reference crop evapotranspiration calculated by Penman-Monteith equation serves as a standard. Results show that the Kp estimated by relative humidity and wind speed can be used to compute ET₀ combined with observed data from 20 cm Chinese pan. There is a satisfactory correlation between ET₀ of 20 cm Chinese pan and Penman-Monteith method over three or more days. However, the Chinese pan coefficient is very dependent on local climate, and it should be determined by comparing the history data or nearby meteorological station data with the Penman-Monteith. Chinese pan can be used for calculating reference crop evapotranspiration in the Loess Plateau.