Evaluation of METRIC-derived ET fluxes over irrigated alfalfa crop in desert conditions using scintillometer measurements

  • K. A. Al-Gaadi
  • V. C. Patil
  • E. Tola
  • R. Madugundu
  • P. H. Gowda
Original Paper


A field study on a 50-ha alfalfa (Medicago sativa L.) irrigated field was conducted to investigate the performance of the remote sensing (RS) based Mapping EvapoTranspiration at high Resolution with Internalized Calibration (METRIC) model in the estimation of evapotranspiration (ET) under the arid conditions of Saudi Arabia. The METRIC model performance was investigated by comparing the energy fluxes estimated by the model to the output of a surface layer scintillometer (SLS) system installed in the field, given the fact that the SLS is efficient in measuring sensible heat fluxes (H) over vegetative areas. Landsat-8 reflectance data were used as inputs for the METRIC model. Results of the study revealed that the HMETRIC data was strongly correlated with the HSLS data with an R 2 value of 0.74 (P > F = 0.0064) and a mean bias error (MBE) of 6.05 W m−2 (6 %). The METRIC model showed a good performance in estimating the hourly latent heat (LE) fluxes compared with SLS data with an R 2 value of 0.81 (P > F = 0.0023), an MBE of 24.46 W m−2 (8 %) and a Nash–Sutcliffe efficiency (NSE) of 0.91. Furthermore, the hourly ET was estimated with an MBE and an NSE of 0.036 mm h−1 (8 %) and 1.00, respectively. Compared to the SLS data, the METRIC model was found to generally provide an efficient and an accurate means of energy fluxes estimation; therefore, ET estimation over the studied irrigated alfalfa crop.


Centre pivot system Evapotranspiration Landsat-8 data Alfalfa field Surface layer scintillometer 



This project was financially supported by King Saud University, Vice Deanship of Research Chairs. The assistance provided by the graduate students M.E. Abass, A.M. Zeyada, and A.G. Kayad in the accomplishment of the field research work was quite valuable. The unstinted cooperation and support extended by Mr. Jack King, Mr. Alan King, and their team in carrying out the research are gratefully acknowledged.


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Copyright information

© Saudi Society for Geosciences 2016

Authors and Affiliations

  • K. A. Al-Gaadi
    • 1
    • 2
  • V. C. Patil
    • 1
    • 3
  • E. Tola
    • 1
  • R. Madugundu
    • 1
  • P. H. Gowda
    • 4
  1. 1.Precision Agriculture Research ChairKing Saud UniversityRiyadhSaudi Arabia
  2. 2.Department of Agricultural Engineering, College of Food and Agriculture SciencesKing Saud UniversityRiyadhSaudi Arabia
  3. 3.Electron Science Research InstituteEdith Cowan UniversityJoondalupAustralia
  4. 4.Forage and Livestock Production Research UnitUSDA-ARS Grazing-lands Research LaboratoryEl RenoUSA

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