Monthly means of daily solar irradiation over Egypt estimated from satellite database and various empirical formulae

Mossad El-Metwally (1) , Lucien Wald (2)

1 Department of Physics
2 O.I.E. - Centre Observation, Impacts, Énergie

Monthly means of daily solar irradiation retrieved from the HelioClim-3 version 3 database (HC3v3), elaborated from Meteosat satellite images, were tested at 14 Egyptian stations along with the model of Yang, Koike and Ye (YKY) and 10 empirical models (EMs) for the period 2004 to 2009. YKY and EMs were fitted to measurements from the period 1980 to 1989. Overall, HC3v3 exhibits a bias of 0.4 MJ m 2 (i.e. 2% of the mean of the observations similar to the best EMs). The root mean square error (RMSE) was 1.8 MJ m 2 (9%) for HC3v3 which is lower than for most EMs. Coefficients of determination (R2) were greater than 0.9 for most models. The regression line between estimates and observations exhibits a slope of 1.01 and an intercept of 0.09 MJ m 2 for HC3v3, reflecting a better performance than other models. HC3v3 shows remarkable constant performance as a function of irradiation or cloudiness compared with EMs and YKY. In general, HC3v3 is preferred to EMs when estimating monthly means of daily solar irradiation in Egypt. It is suggested that more effort is needed towards the validation and promotion of HC3v3 before researchers and practitioners use it rather than EMs.

Mots clés: agro-meteorology; remote sensing; Meteosat; HelioClim; Heliosat-2; Africa; solar radiation; solar energy; validation

Domaines: Océan, Atmosphère; Traitement du signal et de l'image [eess.SP]; Traitement du signal et de l'image [eess.SP]

Mossad El-Metwally, Lucien Wald. Monthly means of daily solar irradiation over Egypt estimated from satellite database and various empirical formulae. International Journal of Remote Sensing, 2013, 34, pp.8182-8198. ⟨10.1080/01431161.2013.834393⟩. ⟨hal-00865173⟩