Sensitivity Analysis of Calculated Evapotranspiration Using Daily Energy Balance Model and Comparing it with SEBAL Model

Nowadays, a lot of models are offered by researchers to estimate surface evapotranspiration (ET) based on meteorological and remote sensing data. Quality of prepared/processed input data has a pivot role on final accuracy of calculated actual ET. In this regard, inputs of a model should be evaluated cautiously before starting the study regarding the effect of each data on the model outputs as well as the required processing cost and time. In this study, actual ET in Shahrkord plain was calculated using Landsat8 satellite images and the proposed daily energy balance model. Results showed a good consistency with lysimeter, pan evaporation and potential ET. The sensitivity of calculated ET to key parameters of the model was then studied with different density of canopy and ET on Julian days of 147, 195, and 291 in 32 control points. Finally, these results were compared with the sensitivity analysis results of SEBAL model studied previously by Khavarian Nahzak (2004). The results showed that the data of group A including air temperature, land surface temperature (LST), income short radiation, and sunny hours, group B including relative humidity and albedo, and group C including the sensitivity of leaf area index and wind have high, medium to high, and low to medium sensitivity, respectively. Thus, it is recommended recording the most sensitive data with more accuracy. Finally, the sensitivity analysis results of proposed daily model showed a considerable similarity with SEBAL model, except for LST.