Daily global solar radiation mapping of Turkey using Meteosat satellite data

Many studies have indicated that the estimation of solar irradiation at ground level using meteorological satellite data has been an alternative and easy method compared to classical methods. In the present work, the incident of solar radiation over Turkey has been estimated at ground level between July 1997 and December 1998. Statistical regressions between ground data and digital satellite data, measured in the visible band (0.4-1.1 mum) by Meteosat radiometer, have been determined and these regression parameters have been used to estimate solar radiation at ground level. This is the so-called statistical method, which uses a simple model because satellites measure only a few parameters among the many that govern radiative transfers. The visible image (C3D) data used in the present work was Meteosat Wefax type. While pursuing our studies the mean daily sum of global solar radiation over Turkey has been determined to be 18.44 MJ m(-2) d(-1) with a correlation coefficient of 0.96. The rms error for the mean daily sum has been evaluated as 1.92 MJ m(-2) d(-1). The monthly mean daily sum of solar radiation has been determined with an rms error of 1.82 MJ m(-2) d(-1) in two years. During this period the maximum value of the daily sum has been found to occur in June 1998 as 28.47 MJ m(-2) d(-1), whereas the minimum has been found to occur in December 1998 as 7.35 MJ m(-2) d(-1). The evaluation procedure, results and possible sources of error are suggested and possible ways of improving the method are described and discussed.