Calibration of METRIC Modeling for Evapotranspiration Estimation Using Landsat 8 Imagery Data

Water resources management needs efcient tools to estimate the rate of water loss through evapotranspiration (ET). High resolution spatial imagery has provided a valuable source of data which their implementation in well-tuned models has the potential of evapotranspiration rate estimations with satisfactory accuracy. Mapping evapotranspiration at high resolution with internalized calibration (METRIC) is basically an energy balance model which has shown a good performance in diferent applications. The model needs to be calibrated for various source of spatial data and with the introduction of new empirical correlations for numerous variables which are used in the model, the model is recalibrated for Landsat 8 multispectral image and applied to intensively cultivated agriculture lands in Alpu (Eskisehir, Turkey). In previous studies, the correlations from previous studies were referenced where the procedure was confusing for many users. In this work, a descriptive step by step procedure is also provided. The meteorological 24 h relative ET was then used to spread the instant ET (at image capture time) estimation into daily 24 h estimation. This approach reduces the errors from multiple correlations and to some extent the efect of short variations like partial cloud coverage.