Sensitivity Analysis of ETo for Five Current Models Using Monte-Carlo Simulation Case study: Bojnourd Synoptic Station

The objective of this study is to analyze the sensitivity of ETo for five models including FAO-Penman- Monteith, modified Blaney-Criddle, Hargreaves, Hargreaves-Samani and Priestley –Taylor. Daily meteorological data of Bojnourd synoptic station including air temperature, relative humidity, actual duration sunshine and wind velocity were used for sensitivity analysis of five models. In order to produce random data at a specific range, Monte-Carlo simulation was performed. Annual and seasonal RMS (mm.day-1) were calculated to indicate the sensitivity of ETo in simultaneous variations of meteorological variables in each model.The results obtained in this study showed that the sensitivity of 0 ET in simultaneous variations of meteorological variables is higher in summer. In all models, the most sensitivity was seen in summer and spring and the least sensitivity was occurred in autumn and winter. Among the studied models, FAO-PM and BC models had the most annual sensitivity and PT model had the least annual sensitivity. All of the models had fairly high correlation coefficient with FAO-PM model but the quantity of RMSE and MAE was different in each model. BC model had the most RMSE and the least RMSE and MAE was seen in MAE and PT. According to the findings in this study, it can be concluded that SH model is fairly suitable for estimation of 0 ET in synoptic station.