Seasonal Variability of the Surface Solar Irradiation in Northeastern Region of Brazil
Abstract
This work aimed at investigating the surface solar irradiation variability and trends in the Northeastern Brazilian region (NEB), relating it with regional climate and environmental characteristics. The statistical analysis used ground data acquired in automated weather stations (AWS) operated by the Brazilian Institute of Meteorology. The results pointed out a remarkable variability in seasonal and annual scales. The cluster analysis provided five regional patterns presenting remarkable temporal complementary regimes for the incoming solar irradiation. The surface solar irradiation achieves the highest average in the Southeastern area of NEB and the lowest average in the Western area in the austral summer. The annual and seasonal trends of the surface solar irradiation were investigated using the Mann-Kendall method and the Sen technique. The surface solar irradiation in the Southeastern area of NEB is decreasing by 50 Wh/m2/year since 2008. On the other hand, it is increasing around 40/m2/year in the semi-arid area along the same timeframe.