干旱荒漠草原应用Penman-Monteith与Penman修正式计算ET_0的偏差分析

Deviation of the Reference Crop Evapotranspiration Estimated by the Penman-Monteith and Penman Methods in Arid Pasture

甘肃天祝草原位于我国西北干旱荒漠草原,应用天祝县二道墩试验站2005年的实测气象资料,利用Penman-Monteith公式和Penman修正式计算参考作物腾发量(ET0)并进行了比较。Penman修正式计算的参考作物腾发量ET0值略小于Penman-Monteith公式计算的值,最大绝对偏差0.5 mm/d。分析发现生育期辐射项ETrad是导致参考作物腾发量ET0产生偏差的主要原因。2种方法计算的空气动力项ETaero差别较小,最大绝对偏差不超过0.2 mm/d。导致计算偏差的原因在于2种公式采用了不同的辐射项和空气动力学项计算公式和参数。2个公式计算的参考作物腾发量具有显著的线性相关性。

Based on the daily meteorological data in Rdaodo experiment station in Tianzhu of Gansu province in 2005, the reference crop evapotranspiration （ET0） calculated by the Penman-Monteith and Penman methods were compared. The results showed that the ETo calculated by Penman method was little lower than that obtained by Penman-Monteith method. The most absolute deviation was 0.5 mm/d between the two methods. During the whole growing season, the radiation item of the reference crop evapotranspiration （ETrad） was the main factor that brought the deviation of ETo. The deviation of aerodynamic item of the reference crop evapotranspiration （ETaero） was very little, and the most absolute deviation was smaller than 0.2 mm/d. The main cause of deviation of ETo was that different equations and parameters were used to calculated the radiation item and aerodynamic item in the equations. The correlations between ETo calculated by the two methods had liner relationship.