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Statistical Analysis of Reference Evapotranspiration on the Tibetan Plateau

2009; American Society of Civil Engineers; Volume: 135; Issue: 2 Linguagem: Inglês

10.1061/(asce)0733-9437(2009)135

1943-4774

Jian‐Sheng Ye, Anhong Guo, Guojun Sun,

Climate variability and models

Net radiation is an important and site-specific component to determine reference evapotranspiration (ET0) . The empirical Angstrom coefficients for radiation estimation in the FAO56 Penman–Monteith (PM) equation were calibrated using observed daily solar radiation and actual sunshine duration on the Tibetan Plateau. The calibrated Angstom coefficients included annual coefficients for nine meteorological stations separately and aggregation of nine stations. The calibrated annual coefficients for each station separately were applied to estimate net radiation and further employed to estimate ET0 using the PM and the Priestley–Taylor (PT) equations on the Tibetan Plateau. Moreover, the Hargreaves (Harg) equation that requires only air temperature was also applied to estimate ET0 . Comparisons of three methods were conducted and the results showed that the PT method overestimated daily ET0 with respect to PM–ET0 and the Harg method underestimated it at all meteorological stations. The PT method was more suitable for the study area in the absence of the parameters necessary for the calculation of PM–ET0 . The Harg equation provides ET0 estimates when only air temperature is available and local calibration in the study can be applied on the Tibetan Plateau.