The Spatial and Temporal Patterns of the Surface Solar Irradiation in Northeastern Region of Brazil
Abstract
Earlier studies have demonstrated that the Northeastern region (NEB) receives the largest surface solar irradiance of the Brazilian territory due to its location in the tropical area and its climate and environment characteristics. The work aimed at investigating the surface solar irradiation variability and trends and relates it with regional climate and environmental characteristics. The statistical analysis was based on ground data acquired in automated weather stations operated by INMET. A quality control procedure was accomplished according to WMO criteria to avoid suspicious data. The results pointed out a significant variability in seasonal and annual scales. The cluster analysis methodology was performed and provided five regional patterns concerning the incoming solar irradiation. There are quite interesting temporal complementary regimes in the region. From December to February, the surface solar irradiation average achieves simultaneously its maximum in the southeastern area and its minimum in the western area of NEB. The Mann-Kendall method and the Sen technique were used to evaluate the annual and seasonal trends of the surface solar irradiation averages. 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 Wh/m²/year in the semi-arid area along the same timeframe.