The purpose of this research is the simulation of the maize function to scenario of climate change to the present and future. So to survey the region climate, daily data, maximum and minimum temperature, precipitation and radiation have been utilized during the period of (1987-2016). In order to simulating of climate in future, firstly the date of IPCM4 model under scenario and 30’s and 50’s with downscaling LARS-WG model. Before the simulation yield of maize, APSIM model was evaluated and validated. To calculate the maize yield the output of LARS model, plant date and were utilized as the cropping input model of APSIM. By variance analysis maize yield was compared in present and future. The results showed that the APSIM model validation can simulate acceptable accuracy and climate parameters change effect on the yield rate of maize. And on the basis of the highest yield in Fasa the lowest in the city Abade in base line. In future under different scenarios of climate change, maze grain yield in Fars province except Abade, other cities are decreasing than base line.

 

So far, several models have been proposed for estimating different climate parameters, but due to the lack of valid and long-term data in some meteorological stations, some models have been difficult to use. The SIMETAV V.1.0 model has been developed in cooperation with the University of California Davis and the Water Resources Authority of California in 2005. The SIMETAW model is a new and innovative tool for the estimation of applied water evapotranspiration (ETAW). SIMETAW simulation model is presented to estimate potential evapotranspiration and also estimate the net amount of water required for irrigation (ETaw). In addition, using this model, you can simulate daily meteorological data from meteorological data. The simulation of daily weather information where there are only monthly averages is a great tool for filling out lost data. In this research, Simetaw simulation model predicts different climate parameters such as solar radiation, minimum and maximum temperature, wind speed, dew point, precipitation and evapotranspiration potential in four different semi-arid climate zones (Mashhad). Dry (Bandar Abbas), moderate and humid (Ramsar) and Mediterranean (Sanandaj) during the years (1967-2017). The results of these studies showed that SIMETAW model has high ability to simulate climate variables and has the highest model accuracy in precipitation simulation (R2 = 0.998) and maximum temperature (R2 = 0.997) for semi-arid climate (Mashhad) , Dew point (R2 = 0.998) for temperate and humid climate (Ramsar), for radiation (R2 = 0.998) and wind speed (R2 = 0.9) for Mediterranean climate (Sanandaj) and minimum temperature (R2 = 0.998) for warm and dry climates (Bandar Abbas).