Diffuse solar radiation in Cairo, Egypt

Ibrahim, Said M.A.

doi:10.1016/0196-8904(85)90072-x

Cited by 28 publications

(12 citation statements)

References 11 publications

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“…This implies that the predictive models adequately estimated the observed values of DHI as a result of high positive correlation between the observed and predicted values of DHI under all sky conditions. This is comparable to the report in literature [9][10][14][15]. However, the correlation coefficient was greatly lowered under clear sky conditions in the six tropical zones.…”

Section: Correlation Analysissupporting

confidence: 81%

“…This implies that 93.7 -99.7% of the clearness index can be accounted using diffuse fraction under all sky conditions. This values are within the range of the report of numerous researchers [9][10][14][15]. However, the value was lowered under clear sky conditions because BHI was highly enhanced than DHI in the solar spectrum.…”

Section: Correlation Analysissupporting

confidence: 71%

“…The intercept bo ranged from 0.907 -2.132; slope, b2, between -0.721 --4.750 and b2 ranged of 0.195 -2.852 were obtained from the correlations under all sky conditions. These values are within the range observed by several researchers [9][10][14][15]. However, the values obtained for clear sky conditions were higher than all sky conditions.…”

Section: Correlation Analysissupporting

confidence: 71%

“…To overcome these shortcomings, different estimation models have been proposed in different locations across the world [5][6][7][8][9][10][11][12][13][14][15][16]. It is therefore imperative to analyse DHI using GHI and clearness index obtained from NASA data.…”

Section: Introductionmentioning

confidence: 99%

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Modeling the influence of cloudiness on diffuse horizon-tal irradiation under various sky conditions in Nigeria

Nwokolo

Ogbulezie

2017

IJPR

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In this study, modeling the influence of cloudiness on diffuse horizontal irradiation (DHI) in six tropical ecological zones in Nigeria (Latitude 4. 75-13.067 o N and Longitude 3.333-13.16 o E) using 22-year data (July 1983-June 2005 was analysed for all sky and clear sky conditions. The result revealed that the absorption of DHI in the global horizontal irradiation (GHI) portion of the solar spectrum is greatly enhanced in the Southern tropical zones as a result of heavy presence of smog, cloudiness, and high water vapour parameters such as relative humidity, dew point temperature and precipitable water thereby increasing the diffuse fraction in the zone. However, in the Northern tropical zones, the absorption of DHI in the GHI portion of the solar spectrum lowered due to presence of low smog, cloudiness and low water vapour parameters thereby reducing the diffuse fraction in the region. The quadratic regression correlation model developed deeming from the model performance test indicates that the proposed model could be used to estimate DHI accurately over the six tropical ecological zones in Nigeria and other locations with comparable sky condition to Nigeria.

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Section: Correlation Analysissupporting

confidence: 81%

Section: Correlation Analysissupporting

confidence: 71%

Section: Correlation Analysissupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Modeling the influence of cloudiness on diffuse horizon-tal irradiation under various sky conditions in Nigeria

Nwokolo

Ogbulezie

2017

IJPR

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“…Hence, simple correlations have been developed to predict the diffuse radiation from other measured climatic data at different locations (Tasdemiroglu and Sever, 1991). In this topic, studies have been made by many researchers and the empirical formula related to different parameters are obtained (Iqbal, 1978;Orgill and Hollands, 1977;Collares-Pereira and Rabl, 1979;Modi and Sukhatme, 1979;Lewis, 1983;Khogali et al, 1983;Vignola and McDaniels, 1984;Rao et al, 1984;Ibrahim, 1985;Alnaser, 1989;Gopinathan and Soler, 1995;Aras et al, 2006;Ulgen and Hepbasli, 2009;Kaygusuz, 1999;Tiris et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

The Calculation of Diffuse Radiation on a Horizontal Surface for Solar Energy Applications

Bakırcı

2012

Energy Sources, Part A: Recovery, Utilization, and Environmenta

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To analyze the systems working with solar energy, it is required that values of the solar radiation belonging to the region have been known. The global solar radiation on a horizontal surface has been measured by the Turkish State Meteorological Service over all of the country, while the diffuse solar radiation has not been measured. In this study, empirical correlations are developed to establish a relationship between the monthly average daily diffuse fraction (H d /H) and monthly average daily diffuse coefficient (H d /H o ) with the monthly average daily clearness index (K T D H /H o ) for the province of Erzurum, Turkey. The six new models for estimating the monthly average daily diffuse solar radiation on a horizontal surface for Erzurum are validated, and the new models are then compared with the 10 models available in the literature. In order to indicate the performance of the models, the statistical test methods of relative percentage error, mean bias error, mean absolute bias error, mean relative error, root mean square error, and correlation coefficient are used. The results indicated that the correlations developed in the study predict diffuse solar radiation reasonably well for future projections.

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Deterministic and probabilistic analysis of different empirical models to estimate monthly mean diffuse solar radiation for composite climatic region of India

Singh

Akella

Manna

2022

Env Prog and Sustain Energy

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This research compares the performance of the models to estimate monthly mean diffuse solar radiation (DSR) on a horizontal surface for composite climatic region of India. The goal is to identify the most accurate model using deterministic and probabilistic analysis through two levels of uncertainty in daily sunshine period to examine the accuracy of the model that will be used to estimate DSR in the region under consideration. The meteorological data were collected from Indian Meteorological Department for the city of New Delhi (28 34 0 N, 77 12 0 E) which comes under composite climatic region prescribed by the Energy Conservation Building Code for India.From the literature, 150 typical models were chosen and categorized into three categories correlating diffuse fraction to sky-clearness index and relative sunshine period.The models are statistically evaluated using well-known statistical indicators in a unique way. In addition, the global performance indicator (GPI) is calculated using scaled values of indicators. The GPI of the chosen models ranged from À2.2912 to 0.2584, with the greatest value indicating the best model. Following that, the models are then ranked in decreasing order of GPI. Finally, the performances of the models are also checked for different locations having similar climatic conditions. Thus, results of this work are useful for impoverished countries as well as remote areas having similar environment conditions.

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Diffuse solar radiation in Cairo, Egypt

Cited by 28 publications

References 11 publications

Modeling the influence of cloudiness on diffuse horizon-tal irradiation under various sky conditions in Nigeria

Modeling the influence of cloudiness on diffuse horizon-tal irradiation under various sky conditions in Nigeria

The Calculation of Diffuse Radiation on a Horizontal Surface for Solar Energy Applications

Deterministic and probabilistic analysis of different empirical models to estimate monthly mean diffuse solar radiation for composite climatic region of India

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