Increasing the accuracy of solar radiation interpolation by combining data in the cokriging method

Accurate calculation of the amount of solar radiation in an area has an effective role in the climatology and agriculture of the region. Point measurements at ground stations using pyranometers are the most accurate method of estimating solar radiation, in which measurements are extended to a continuous surface using spatial interpolation methods. The main purpose of this study is to increase the accuracy of solar radiation zoning in Iran using Cokriging method. For this purpose, the amount of solar radiation was first calculated using the Digital Elevation Model (DEM) and the Solar Radiation spatial toolbox in ArcGIS software. Then the correlation coefficient(R) between the obtained values from the software with the values of solar radiation measured at ground stations was calculated. According to R = 0.713 between these two data, by Cokriging method, these two data were combined and the continuous surface of solar radiation for the whole of the country was calculated. The results showed that the calculation of solar radiation using Area Solar GIS tool is not accurate enough compared to ground data, but the combination of the two data, while affecting the topography in the calculation of solar radiation, increases the interpolation accuracy by 11%. Therefore, although existing models may not be accurate enough to estimate solar radiation on a national scale compared to terrestrial data, they can be used to improve the accuracy of terrestrial data zoning. According to the final map, most regions of the country receive solar radiation above the global average (340 w/m2).