The Cloud cover index (Ceff) obtained from satellite images contains information on cloud amount and their optical thickness. It is the chief climate data for the assessment of solar energy resources in most radiative transfer models, particularly for the model BRASIL-SR. The wide range of climate environments in Brazil turns Ceff determination into a challenging activity and great effort has been directed to develop new methods and procedures to improve the accuracy of these estimations from satellite images. This paper evaluates three tested methodologies for improving the model output BRAZIL-SR. A comparison of methods was done by comparing the measured and estimated solar irradiation by BRAZIL-SR model for the town of Petrolina in the semi-arid area of northeastern Brazil. The ground truth data was provided by the solar radiation station located at Petrolina-PE, in Brazilian Northeast region, which is part of the project SONDA. Results have shown that the new methodologies, generated coefficients of cloud effective with lower values, thus it has achieved the goal of having an image of cloud cover with values closer to the values observed in cold clouds . However, the global solar irradiation estimated by BRAZIL-SR model now provides for a systematic overestimation indicating that improvements are still necessary methods in order to identify the most reliable values of effective cloud cover from satellite images.
Redes Sociais