Global solar irradiance in Cordoba: Clearness index distributions conditioned to the optical air mass

The biological and photochemical effects of solar radiation and solar energy applications make it really important to characterize the variability of this component. In view of the fact that the clearness index indicates not only the level of availability of solar radiation but also the changes in atmospheric conditions in a given location, since the classic Liu and Jordan study, many papers have dealt with its statistical distribution. Specifically, Tovar et al. [Tovar J, Olmo FJ, Alados-Arboledas L. Solar Energy 1998;62(6):387–393] proposed a model to represent the probability density distributions of the instantaneous clearness index conditioned to the optical air mass from measurements recorded in Granada (Spain). In this work, we have proved the applicability of this model in a different location, Cordoba (Spain), finding that the parameters for fitting the model depend on both the optical air mass and the geographic and climatic conditions.