Calibration of Angstrom Equation for Estimating Solar Radiation using Meta-Heuristic Harmony Search Algorithm (Case study: Mashhad-East of Iran)

The solar radiation received by earth surface is one of the most applicable parameter that is usable in hydrology, agriculture, climatology and meteorological modeling. Many different experimental equations had been suggested by researchers to estimate this parameter in different climates. In this paper, Meta-Heuristic Harmony Search Algorithm (HS) has been developed for determining the Angstrom equation coefficients, by using the daily solar radiation and daily sunshine duration data of Mashhad Synoptic station from 1993 to 2007 (4765 daily data). Also the Angstrom equation coefficients have been estimated for all the of them for test.Three statistical parameters Root Mean Square Error (RMSE), Index of % of data used for train and 30%month. 70 agreement (d) and Mean Bias Error (MBE) have been used to estimate error and model validation. The results showed that, the value of RMSE, d and MBE for HS algorithm were 0.1265, 0.8323 and -0.0280, respectively. The value of Angstrom coefficients for Mashhad station in HS method is 0.4743 (for b coefficient) and 0.2657 (for a coefficient). The value of correlation in this method is obtained (R= 0.9047).