Calibration of earth surface received radiation in north east of Iran

The solar radiation reached the earth surface (RS) has wide applications in many areas of agriculture engineering, irrigation and hydrology and that’s why various methods have been represented for its estimation, which Angstrom – Prescott equation is one of the most important equation in this field. This equation has experimental coefficients that are different for any situation. Because of the importance of Rs, various methods have developed for its estimation. The radiation reached to earth surface is evaluated by using average daily sunny hours data of synoptic affiliated to the general state metrological office in the north of Khorasan, Khorasan Razavi and southern Khorasan 1988- 2016. The Angstrom – prescient method has been used for estimating solar radiation of earth surface in the studied area. In this research, the a & b coefficients were calculated by using Ferrer's method fastly and then have been placed in Angstrom equation. Finally, the radiation equivalent map of the studied area has been drawn and analyzed by using kriging interpolation model. The research outcome indicated that southern, south-east regions and at the next level, the center of the studied area especially Nehbndan station have more potential for receiving solar radiation. The minimum monthly received radiation of area during January and December month in the north and northwest of this region, which are 7.98 and 7.36 megajoules per square meter respectively. The maximum received radiation of area occurs in July about 30.24 megajoules. South and south-east regions up to the center of the of the area Nehbandan station have more potential for receiving in terms of radiation during summer & spring seasons respectively.