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Khalil S.A.,National Institute for Space Research | Shaffie A.M.,Egyptian Meteorological Authority EMA | Shaffie A.M.,Al Baha University
Renewable and Sustainable Energy Reviews | Year: 2016

Solar irradiance is attenuated spectrally when passing through the earth's atmosphere and it is strongly dependent on sky under cloudless conditions. The prevailing winds, which may transport moisture or aerosol particles from distant sources, play a major role in the seasonal variation of turbidity. A direct measurement of the aerosol transmittance is not possible due to the strong influence of the other atmospheric components. During the last century, a number of atmospheric turbidity indices were introduced and several methods were developed to determine their values. This paper provides a review of the effect of aerosols on solar radiation budget by considering two common turbidity parameters including the Linke turbidity factor (TL) and Angstrom turbidity coefficients (β) and (α). Furthermore, an investigation of atmospheric turbidity has been undertaken in Egypt (Cairo, Aswan and Marsa-Matruh), from 1990 to 2013: turbidity indexes, namely, Linke factor (TL) and Ångström coefficient (β). The Angstrom turbidity coefficients (β) have been determined at fixed air masses during the first and second halves of the day at different spectroscopic solar energy bands, the maximum values of turbidity in the summer due to dust storms and vertical convection. And low values of turbidity index in the winter, due to precipitation removal as well as relative humidity-impacted deposition, but the middle values of turbidity were observed in the spring and autumn seasons. The maximum values of the Angstrom turbidity coefficient occur around the noon time. Annual variations show lowest values in winter months and highest values in both spring months, due to the khamsin continental wind lead to more polluting effects on the prevailing air masses and summer months due to hot air mass and large water vapor contents. The Angstrom turbidity coefficient decreases with increase in both wavelengths and optical air masses. © 2015 Elsevier Ltd. Source


Sharobiem W.M.,Egyptian Meteorological Authority EMA
International Journal of Remote Sensing | Year: 2010

Direct Sun observations made by a Brewer spectrophotometer II were used to measure the ozone column (in DU), the ultraviolet radiation in the B region (UVB) (mW m-2 nm-1) and the aerosol optical depth (AOD) (320.1 nm) at Matrouh (31° 20′ N, 27° 13′ E) during the period January 1999 to December 2006. The mean monthly data are used to calculate the seasonal variation and trend in column ozone, UVB and AOD. The study shows that the seasonal variations in the ozone column and damage ultraviolet (DUV) radiation take maximum values in spring (320DU) and summer (105.42mW m-2 nm-1) respectively, while the maximum value of AOD (0.14) was found at hot season. The analysis of the mean annual data from 1999-2006 for column ozone, UVB radiation and AOD show positive trends, with values of 0.059, 0.120 and 0.001, respectively. © 2010 Taylor & Francis. Source


Khalil S.A.,National Institute for Space Research | Khalil S.A.,Al Baha University | Shaffie A.M.,Egyptian Meteorological Authority EMA | Shaffie A.M.,Al Baha University
Renewable and Sustainable Energy Reviews | Year: 2013

The measured hourly daily data of total, direct and diffuse solar irradiation incident on a horizontal and an inclined surface for Cairo, Egypt (Lat. 30 05′N and Long. 31 15′E), during the period (1990-2010) are analyzed. The regression equations between (G/Go) and meteorological variables along with the values of MBE, RMSE, MPE, R2 and the t-test statistics are summarized in this research. The values of correlation coefficients (R2) are higher than 0.95 and the values of the RMSE are found in the range 3.13-6.34, thus indicating a good agreement between measured and calculated values of the total solar radiation (G). The models of Eqs. (10), (11) and (14) have well estimated the total solar irradiation in the selected location during the time period in the present study. For all models, the absolute values of the MPE indicate very good agreement between measured and calculated values of the diffuse solar fraction (Gd/G) or the diffuse solar transmittance (Gd/Go) and clearness index Kt, relative number of sunshine hours (S/So) and their combination. The models of Hay (Ha), Skartveit and Olseth (SO) and Perez et al. (P9) give the most accurate predictions for the south-facing surface, and Hay (Ha) and Perez et al. (P9) models performs better as estimated for the west-facing surface. © 2013 Elsevier Ltd. Source


Saleh A.M.M.,Egyptian Petroleum Research Institute | Trad M.A.,Egyptian Meteorological Authority EMA
Construction and Building Materials | Year: 2011

This work aims to generate an asphalt performance grading map for Egypt based on the SUPERPAVE and LTTP programs. To achieve this aim, 60 weather stations data and air temperatures (maximum and minimum) recorded by Egyptian Meteorological Authority (EMA) collected covered of minimum 30 years of continuous temperature recording. The collected data and the calculated standard deviation were used to obtain surface and pavement temperatures for 21 representative stations for various climatic regions of Egypt. It revealed that four types of asphalt binder performance grades (at 98% reliability) are recommended for use in Egypt. The grades are PG 70-10, 76-10, 76-16 & 76-28. © 2010 Elsevier Ltd. All rights reserved. Source


Khalil S.A.,National Institute for Space Research | Khalil S.A.,Al Baha University | Shaffie A.M.,Egyptian Meteorological Authority EMA | Shaffie A.M.,Al Baha University
Advances in Space Research | Year: 2013

The hourly and daily measured clear-sky global solar radiation (G) and biologically important effective erythematic radiation (EER) incident on a horizontal surface at Cairo, Egypt (latitude 30° 05′ N & Longitude 31° 15′ E), during the period from January 1995 to December 2005 are used in this paper. The relationship between daily integrated totals of EER and the daily totals of broadband global solar radiation (250-2800 nm) is established. The temporal variability of the percentage ratio of the total daily erythema to total daily broadband solar global irradiation (EER/G) is determined. The monthly and the seasonal averages of the extraterrestrial UVB solar radiation, Mesurad and estímated UVB solar radiation and clearness index KtUVB of UVB radiation are discussed. The average monthly mean variation of slant ozone (Z) and UVB transmission (KtUVB) at the present work are found. The two variables show an opposite seasonal behavior, and the average monthly of slant ozone column and UVB transmission values shows the relationship between them in a clearer way than those of daily values. The estimated values of UVB solar radiation a good agreement with the measured values of the UVB solar radiation, the difference between the estimated and measured values of UVB solar radiation varies from 1.2% to 2.8%. The effect of the annual cycles of solar zenith angle (SZA) and total column ozone (TCO) on the ratios (EER/G) are presented and the correction factors are determined for removal of the ozone cycle. The seasonal variability of EER/G is also discussed. The effect of the annual cycles of solar zenith angle (SZA) and total column ozone (TCO) on the ratios (EER/G) is presented and the correction factors are determined for removal of the ozone cycle. © 2012 COSPAR. Published by Elsevier Ltd. All rights reserved. Source

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