The region of the study is the area of Andalusia, in the southern part of Iberian Peninsula (Figure 1), covering around 87.000 km2. The region is located in the transition zone from middle latitudes to subtropical climates (latitudes 35° 30′ to 38° 30′ N and longitudes 7° 30′ to 1° 30 W), with the Atlantic Ocean and the Mediterranean region in the southern bound.

2.1. Dataset

The experimental dataset used in the study includes four year (2003-2006) of daily global radiation in the horizontal surface values, measured at 166 meteorological stations along the study region.

The stations are owned and maintained by the Andalusia Regional Government, and are part of the Agricultural and Environmental monitoring network. The location of the station, displayed in Figure 2, covers almost homogeneously the region. The 166 stations were divided into two groups: two-third of the stations (112) was used to train the models (training dataset) and one-third (54) was used for the validation process (validation dataset). Both groups were selected trying to cover homogenously the study region.