【摘要】 对ET0计算公式设定条件和重要影响因子的实验率定研究:揭示了Penman-Motheith(PM)等公式定义中叶面冠层阻力、反射率及Angstrom公式中的a、b值不是定值,而是一个随作物生长变值,并建议将变化的叶面冠层阻力、反射率及季节a、b值代入计算公式,可得到更加切合实际的ET0值;鉴于参考作物有两种:牧草和紫花苜蓿,不同的参考作物蒸发蒸腾量计算公式对应着不同的参考作物,求得两种参考作物蒸发蒸腾量的转换系数Kr可进行不同参考作物间的转换计算;揭露了参考作物(苜蓿)冠层光合有效辐射(PAR)及冠层顶部光合有效辐射(PARCAN)在一定程度上影响ET0值,气孔导度和物质积累等生理、生化作用也与ET0的变化过程十分相关;并对ET0标准ASCE-PM、PM、MP公式中主要气象输入因子对ET0、ETa、ETr值的潜在支配作用进行了研究。有助于ET0学科中重要问题的引领研究及精确估计。更多还原

【Abstract】 This paper carries the experimental research on the calculation conditions and the major factors of ET₀ formulas.It is revealed that the leaf surface resistance and the albedo in the Penman-Montheith（PM） equation,and the value of a and b in the Angstrom equation are not constant,and they change with the crop growing stages.It is suggested to calculate the values of a and b,the surface resistance,and albedo according to the crop growing stages to obtain the actual ET₀.In view of the fact that there are two kinds of reference crops: grass and alfalfa,for the two evapotranspiration formulas,it is necessary to calculate the conversion coefficient K_r to transform between the two equations for different reference crops.The values of PAR and PARCAN of reference crop（alfalfa） to certain extent have influences on ET₀ value;stomata conduction and material accumulation also change with ET₀.The paper also conducts studies on the latent dominating effects of the major meteorological factors on ET₀,ET_a and ET_r in the standard ASCE-PM,PM and MP formulas.These results are helpful for ET₀ studies and estimates.更多还原