Comparison of the Hargreaves-Samani equation and the Priestley-Taylor equation for estimating reference crop evapotranspiration in the North China Plain

摘要

FAO56 Penman-Monteith equation, Hargreaves-Samani equation and Priestley-Taylor equation were used to estimate the reference crop evapotranspiration(ETo) in the North China Plain during the summer and winter, using climatology data from 1960 to 2013 including daily mean wind speed, average relative humidity, sunshine percentage, mean, maximum and minimum temperature at 10 weather stations over the North China Plain. By comparing the Hargreaves-Samani equation and Priestley-Taylor equation with FAO56 Penman-Monteith equation, we found that there existed interdependency between ETo derived from the former two equations and FAO56 Penman-Monteith equation. The interdependency in summer is higher than that in winter. In summer, the average pearson's correlation coefficient between ETo calculated by Hargreaves-Samani equation and FAO56 Penman-Monteith equation is 0.81, and the average pearson's correlation coefficient of ETo calculated by Priestley-Taylor equation and FAO56 Penman-Monteith equation is 0.87, while the corresponding pearson's correlation coefficient for them in winter is 0.69 and 0.51. Respectively, for the ETo calculation in summer, interdependency between Priestley-Taylor equation and FAO56 Penman-Monteith equation is higher than that between Hargreaves-Samani equation and FAO56 Penman-Monteith equation, and vice versa for winter.