Combining the satellite imagery with bright sunshine hours: A review

Present article is a review of recent researches on linking the satellite image data to surface measured bright sunshine hours. It first gives some basics on estimation procedures of the daily global solar irradiation on horizontal surface with the daily bright sunshine hours. Second, a satellite based model is presented briefly. Then, two recent combined models are reviewed and compared with the conventional models. The results on using one of the presented methods are discussed and recommended, for a couple of various cases which are classified by available data of the site of interest. It is concluded that the use of one of the combined model gives one of the best estimation performance for the daily global solar irradiation at the Earth's surface, whenever both of the data of bright sunshine and cloud index are available. However, satellite based model HELIOSAT also performs with high accuracy except for a number of days of one of the data sets. Hence, another conclusion is that, for the daily estimations, the use of HELIOSAT type satellite based models should be preferred, instead of using an Angström-Prescott type correlation of a location at a far point and/or having a different climate. Finally, a quadratic correlation which was tested for too many locations all over the world also performs quite accurately. Therefore, if only the bright sunshine hour data is available for a site, use of this quadratic correlation should be preferred.