بررسي مدل هاي مختلف برآورد تابش خورشيدي به منظور معرفي مناسب ترين مدل در يك اقليم نيمه خشك

The Investigation of different Models of estimating Solar Radiation to Recommend the Suitable Model in a Semi-arid Climate

The solar radiation received by earth surface is one of the most applicable parameter that is usable in projects and hydrology, agriculture, Meteorology and climatological modeling. Since very expensive instrument for measuring the radiation, had been suggested many different experimental equations by researchers to estimate this parameter in different climate. In this research, seven models of estimate of short wave solar radiation including 1- the model of Angstrom-Prescott suggested by FAO, 2- the calibrated model of Angstrom-Prescott by Khalili & Rezaei Sadr, 3- the calibrated model of Angstrom-Prescott by Khalili & Rezaei Sadr by using Absorption spectrum of water vapor, 4- calibrated model of Angstrom-Prescott by Alizadeh & Khalili, 5- Linear Regression Model of Alizadeh & Khalili, 6- Sabbagh model and 7- Glover & McCuloch model, were investigated to recommend the suitable model for this area. Results of comparing calculated amounts of these models whit amounts of measured by piranometr shows that by using coefficient of determination, the models of 1, 2 and 4 (equal 0.8505, 0.8507 and 0.8507 respectively) have higher correlation with actual amounts. But because of a little different of R2 between these models and less amounts of RMSE, MBE and t indexes (equal 2.68, 0.16 and 0.59 respectively) in model 1, can recommend this model as the suitable model of estimate of solar radiation in this climate. Keywords: Short wave solar radiation, Piranometr, Absorption spectrum of water vapor, Coefficient of determination, Semi-arid climate