该文根据甘肃张掖气象站1991~2000年的气象资料,利用Hargreaves公式和Penman-Monteith公式计算了参照作物需水量(ET0).对比分析结果表明:Hargreaves公式计算的ET0H年值比Penman-Monteith公式的计算ET0PM偏低,而在年内6、7、8月份,ET0H>ET0PM,9月份两种方法计算结果几乎相等,其他月份ET0H<ET0PM.造成这种结果的原因是风速和降雨的影响.根据两种方法的计算结果,提出了适合西北干旱区ET0的计算公式.
According to the climate data from 1991 to 2000 at Zhangye weather station, using Hargreaves equation and Penman-Monteith equations, the reference crop evapotranspiration (ET0) was calculated. Results show that the annual value of ET0 calculated by Hargreaves equation is lower than that calculated by Penman-Monteith equation. ET0H will be greater than ET0PM in June, July and August. The calculating value will almost be equal in September, and ET0H will be lower than ET0PM in other months. The difference is caused by precipitation and wind speed. Based on the estimating ET0 by the two equations, the ET0 calculating equation applied in arid-area of Northwest China is put forward.