Validation of the Surface Downwelling Solar Irradiance Estimates of the HelioClim-3 Database in Egypt

摘要: HelioClim-3 (HC3) is a database providing time series of the surface downwelling solar irradiance that are computed from images Meteosat satellites. This paper presents validation results hourly global horizontal (GHI) and direct normal (DNI), i.e., beam at incidence, versions four five HC3 seven Egyptian sites. The performed for all-sky conditions, as well cloud-free conditions. Both provide similar performances whatever Another comparison made with estimates provided by McClear restricted to All databases capture temporal variability GHI in all being superior cases. In conditions GHI, relative root mean square error (RMSE) fairly similar, ranging 6% 15%; both exhibit smaller bias than McClear. offers an overall better performance DNI estimates. For RMSE ranges 10% 22%, except one station, while, DNI, not so good two stations measurements.