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Remote Sens. 2015, 7(7), 9269-9291;

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

Masdar Institute, Research Center for Renewable Energy Mapping and Assessment, P.O. Box 54224 Abu Dhabi, UAE
MINES ParisTech, PSL Research University, O.I.E. – Centre Observation, Impacts, Energy, CS 10207 – 06904 Sophia Antipolis cedex, France
Egyptian Meteorological Authority, Cairo 11599, Egypt
Physics and Mathematical Engineering Department, Faculty of Engineering, Port Said University, Port Said 42526, Egypt
Astronomy and Meteorology Department, Faculty of Science, Cairo University, Giza 12613, Egypt
Laboratoire Inter-universitaire des Systèmes Atmosphériques, Universités de Paris-Est Créteil et Paris-Diderot, Paris 94010, France
Physics Department, Faculty of Science, Port Said University, Port Said 42526, Egypt
Deutscher Wetterdienst, Offenbach 63067, Germany
Author to whom correspondence should be addressed.
Academic Editors: Richard Müller and Prasad S. Thenkabail
Received: 29 April 2015 / Revised: 4 July 2015 / Accepted: 10 July 2015 / Published: 21 July 2015
(This article belongs to the Special Issue Remote Sensing of Solar Surface Radiation)
Full-Text   |   PDF [749 KB, uploaded 21 July 2015]   |  


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

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Eissa, Y.; Korany, M.; Aoun, Y.; Boraiy, M.; Abdel Wahab, M.M.; Alfaro, S.C.; Blanc, P.; El-Metwally, M.; Ghedira, H.; Hungershoefer, K.; Wald, L. Validation of the Surface Downwelling Solar Irradiance Estimates of the HelioClim-3 Database in Egypt. Remote Sens. 2015, 7, 9269-9291.

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