Evaluation of the Efficiency of Solar Radiation Estimation Models Using Satellite Imagery

In addition to use in climate models, solar radiation plays a decisive role in development of solar systems programs in different areas. With significant advances in telecommunication and communication sector, the use of satellite imageries for land-based observations has found a wider role than traditional observations. Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products are available to the public free of charge and have a reasonable resolution of 1km × 1km. In this research, it was tried to calculate the amount of total solar radiation in 4 stations in Iran, using the Earth's surface and atmospheric MODIS data as an input of the parametric and the Angström-Prescott (AP) models and to compare the results with ground-level observations. The AP model output obtained from the MODIS data (APRS) was compared with the AP model output obtained from ground level observation data (APGS). By comparing the results, it was found that the APRS model is more accuracy than the APGS model on cloudy days. So that the amount of RMSE and MBE indices for the APRS model on cloudy days were 41.74 W/m2 and 19.70 W/m2, respectively, and for APGS model were 43.6 W/m2 and 34.25 W/m2, respectively. However, the accuracy of the APGS model on sunny days was higher than that of the APRS model. Although the limitations of ground data (point observations) could be an effective factor in choosing one of both models. Results also indicate a high accuracy of the parametric model (RMSE = 16.56 W/m2 and R2 =0.93), especially on cloudy days. On the other hand, despite of high accuracy of the parametric model, the application of APRS model is easy. However, long period sunshine hour’s data are needed for calibration of AP coefficients in different regions.