LAUSR

Abstract A field experiment was performed to evaluate the Mapping Evapotranspiration at High Resolution using Internalized Calibration (METRIC) model that was used for mapping surface energy balance (SEB) components (net radiation (Rni), soil heat flux (Gi), sensible heat flux (Hi), and latent heat flux (LEi)) at times of Landsat satellite overpasses in conjunction with the actual evapotranspiration (ETa) and crop coefficient (Kc) for a superintensive, drip-irrigated olive (Olea europeae L. cv Arbequina) orchard. The orchard is located in the Pencahue Valley, Maule Region, Chile (35 23' LS; 71 44' LW; 96 m above sea level), and the study was conducted on an experimental plot of 21.1 ha during the 2011/2012 and 2012/2013 growing seasons. Model performance was evaluated using measurements of LEi, ETa and Kc that were obtained from an eddy covariance (EC) system. Olive-specific functions for estimating aerodynamic roughness (zom), leaf area index (LAI), and Gi were employed in the METRIC algorithm. In addition, submodels of Rni and Gi were evaluated via ground-truth measurements from a Fritchen-type net radiometer and soil flux plates, respectively. The results indicated that the errors within the METRIC model for the SEB components were between 2% and 5% of the observed values, while those for ETa and Kc were between 4% and 6% of the EC values. In addition, both the root mean square error (RMSE) and mean absolute error (MAE) for the SEB components were less than 46 W∙m−2 at the times of satellite overpass. The RMSE and MAE values for the 24-h ETa were 0.42 and 0.31 mm·day−1, respectively, while the corresponding values for Kc were 0.09 and 0.02, respectively. The coefficients of variation (CVs) for the SEB components, ETa and Kc were less than 15%, and the largest intraorchard spatial variability occurred for LEi and, thus, ETa. The errors and uncertainties in the SEB and ETa estimates were small enough to warrant application of the METRIC model with olive-specific functions for zom, LAI and Gi to superintensive drip-irrigated olive orchards.