Estimation of clearness index from different meteorological parameters in IRAQ

Abstract

The aim of this paper is to estimate the mean monthly values of clearness index in five meteorological stations in Iraq (Mosul , Kirkuk , Rutba , Baghdad , Nasiriya) for the period (1970-2000) using different meteorological parameters. Five different models (Linear , Quadratic , Logarithmic , Linear logarithmic , Power) were used to estimate clearness index. The performance of this regression models were evaluated by comparing the calculated clearness index and the measured clearness index. Several statistical tests were used to control the validation and goodness of the regression models in terms of correlation coefficient, coefficient of determination , Mean absolute error and root mean square error. Results showed that Linear model between (KT & n/N) and between (KT & Rainfall) were the best fit in all stations. Quadratic model were the best fit between (KT & cloudiness) , and power model were the best fit between (KT &Evaporation). Linear model and Quadratic model were the best fit between (KT & RH) , while power model , Quadratic model , and Linear model were the best fit between (KT & Tmean).