| Summary: | Crop modeling uncertainty is expected to be high under weather data limitations; thus, jeopardizing decision-making on food-water security. Missing near-surface wind speed (u<sub>2</sub>) data required to accurately estimate reference evapotranspiration (ET<sub>o</sub>) seemed to significantly affect both the potential evapotranspiration (ET<sub>P</sub>) and yield simulations for data-scarce windy regions. In this study, the uncertainty in crop modeling based on different ET<sub>P</sub> approaches was assessed. In this regard, wheat yield and evapotranspiration were simulated with the CSM-CERES-Wheat model using either the Priestley-Taylor/Ritchie (PT) or the Penman-Monteith DSSAT (PM) methods under “rain-fed, low-nitrogen stress”, “rain-fed, high nitrogen stress”, “full irrigation, low nitrogen stress”, and “full irrigation, high nitrogen stress” scenarios for a u<sub>2</sub> range from 0.8 to 3.5 m s<sup>−1</sup>. The daily weather data required to run the model were retrieved from 18 semi-arid areas located in western Iran. The statistically significant differences in mean yield and cumulative distribution were determined by the non-parametric Wilcoxon signed-rank and the Kolmogorov-Smirnov tests, respectively. The deviation in evaporation and transpiration simulated by applying PT and PM was lower under rain-fed condition. Under “rain-fed, low-nitrogen stress”, the PT-simulated yield deviated significantly (<i>p</i> < 0.05) from PM-simulated yield by more than 26% for the sites with u<sub>2</sub> above 3 m s<sup>−1</sup>. The deviation in ET<sub>P</sub> estimates did not, however, lead to statistically significant difference in yield distribution curves for almost all sites and scenarios. Nitrogen deficiency resulted in a smaller difference in yield for rain-fed condition. The yield results showed a deviation below 6% under full irrigation condition. Under windy rain-fed condition, high deviation in leaf area index (LAI) and ET<sub>P</sub> estimates caused a large difference in the actual transpiration to potential transpiration ratio (T<sub>a</sub>/T<sub>P</sub>), and yield. However, the deviation between PT- and PM-simulated LAI and T<sub>a</sub>/T<sub>P</sub> for the full irrigation scenarios was less than 6%. Overall, the results from this study indicate that when soil moisture is depleted, resembling rain-fed condition, simulation of yield appears to be highly sensitive to the estimation of ET<sub>P</sub> for windy areas.
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