Evaluation of Temperature-Based Methods for the Estimation of Reference Evapotranspiration in the Yucatán Peninsula, Mexico

Estimation of reference evapotranspiration (${\mathrm{ET}}_{\mathrm{o}}$) using air temperature is particularly attractive for places where solar radiation, wind speed, and air humidity data are not readily available. In this study, seven temperature-based (TET) models and the standardized reference evapotranspiration equation for short canopies method were compared. Using only temperature data from the Yucatán Peninsula, México, the Food and Agriculture Organization of the United Nations (FAO)-Penman-Monteith (PMT) model was used to estimate ${\mathrm{ET}}_{\mathrm{o}}$. Results from the temperature-based models are compared with FAO-56 daily ${\mathrm{ET}}_{\mathrm{o}}$ calculations using the Nash-Sutcliffe model efficiency coefficient (NSE), the coefficient of determination ($R^2$), mean absolute bias error (MAE), mean absolute percentage error (MAPE) and root mean square (RMSE). The results show that the noncalibrated PMT expression using temperatures alone produced the best results, with $\mathrm{RMSE}=0.7\mathrm{mm}{\mathrm{d}}^{-1}$. The Hargreaves-Samani calibrated ($\mathrm{RMSE}=0.74\mathrm{mm}·{\mathrm{d}}^{-1}$) and Camargo calibrated ($\mathrm{RMSE}=0.78$) models exhibited the next best performance. RMSE values were as high as $1.56\mathrm{mm}·{\mathrm{d}}^{-1}$ for the other models.