Assessment of different equations to estimate potential evapotranspiration versus FAO Penman Monteith method

This study aims to assess mass transfer-based models versus the FAO Penman-Monteith model to detect the best model using linear regression under different weather conditions. For this purpose, weather data were gathered from 181 synoptic stations in 31 provinces of Iran. The potential evapotranspiration was estimated using 11 mass transfer-based models and was compared with the FAO Penman-Monteith model. The results showed that the Albrecht model estimates the potential evapotranspiration better than other models in the most provinces of Iran (23 provinces). The best values of R2 were 0.9854 and 0.9826 for the Brockamp-Wenner and Albrecht models in Bushehr (BU) and TE provinces, respectively. Finally, a list of the best performance of each model has been presented. The best weather conditions (not only for Iran but also for all countries) to use mass transfer-based equations are 23.6-24.6 MJ/m2/day, 12-26 ˚C, 18-30 ˚C, 5-21 ˚C, and 2.50-3.25 m.s-1 (with the exception of Penman) forsolar radiation, mean, maximum, and minimum temperature, and wind speed,respectively. Results are also useful for selecting the best model when researchers mustapply temperature-based models on the basis of available data.

Keywords:

Evapotranspiration , FAO Penman Monteith , Humidity , Iran , Linear regression , Mass transfer