Correlations for direct normal and global horizontal irradiation on a French Mediterranean site

Louche, A.; Notton, Gilles; Poggi, Philippe; Simonnot, G.

doi:10.1016/0038-092x(91)90072-5

Cited by 157 publications

(62 citation statements)

References 15 publications

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“…These results show that the burn width gives more information about the variation of DSI high-resolution temporal data (1 h), whereas counting the time length of the burn for short periods only gives information as to whether the Sun is visible (i.e., whether DSI is higher than a certain value). It is remarkable that the correlation between DSI and burn width at hourly resolution is as good as other relationships found by other authors at lower temporal resolution (daily, monthly, seasonally, or annually) using only SD and linear and quadratic correlations (Benson et al, 1984;Louche et al, 1991;Nfaoui and Buret, 1993;Maduekwe and Chendo, 1995;Stanhill, 1998;Power, 2001). Table 2.…”

Section: Burn Width and Its Relationship With Dsisupporting

confidence: 72%

Using digital image processing to characterize the Campbell–Stokes sunshine recorder and to derive high-temporal resolution direct solar irradiance

et al. 2015

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Abstract. The Campbell-Stokes sunshine recorder (CSSR) has been one of the most commonly used instruments for measuring sunshine duration (SD) through the burn length of a given CSSR card. Many authors have used SD to obtain information about cloudiness and solar radiation (by using Ångström-Prescott type formulas), but the burn width has not been used systematically. In principle, the burn width increases for increasing direct beam irradiance. The aim of this research is to show the relationship between burn width and direct solar irradiance (DSI) and to prove whether this relationship depends on the type of CSSR and burning card. A method of analysis based on image processing of digital scanned images of burned cards is used. With this method, the temporal evolution of the burn width with 1 min resolution can be obtained. From this, SD is easily calculated and compared with the traditional (i.e., visual) determination. The method tends to slightly overestimate SD, but the thresholds that are used in the image processing could be adjusted to obtain an improved estimation. Regarding the burn width, experimental results show that there is a high correlation between two different models of CSSRs, as well as a strong relationship between burn widths and DSI at a hightemporal resolution. Thus, for example, hourly DSI may be estimated from the burn width with higher accuracy than based on burn length (for one of the CSSR, relative root mean squared error is 24 and 30 %, respectively; mean bias error is −0.6 and −30.0 W m −2 , respectively). The method offers a practical way to exploit long-term sets of CSSR cards to create long time series of DSI. Since DSI is affected by atmospheric aerosol content, CSSR records may also become a proxy measurement for turbidity and atmospheric aerosol loading.

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Section: Burn Width and Its Relationship With Dsisupporting

confidence: 72%

Using digital image processing to characterize the Campbell–Stokes sunshine recorder and to derive high-temporal resolution direct solar irradiance

et al. 2015

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“…Potential daily clear-sky beam irradiation is the beam radiation that would have been incident if the sky had been clear all day (Power, 2001a). Following McCormick (1989, 1992), Louche et al (1991), Gueymard (1993), andPower (2001c), monthly averages of the potential daily clear-sky beam irradiationH bc can be obtained confidently from…”

Section: Quantifying Turbiditymentioning

confidence: 99%

Comparison of aerosol and climate variability over Germany and South Africa

Power

Goyal

2003

Intl Journal of Climatology

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A radiation-based model is employed to evaluate seasonal, interannual, and spatial variability within monthly averaged turbidity (the total column amount of aerosol) at eight stations in South Africa and 13 stations in Germany. Germany has a strong seasonal turbidity trend of summer maxima and winter minima. In South Africa the seasonal turbidity trend is weaker, but, on average, turbidity peaks in spring and is lowest in autumn and winter. Over the last several decades, turbidity over Germany has decreased significantly at seven stations. The impacts of the El Chichón and Pinatubo volcanic eruptions are evident in the turbidity signatures over Germany. Four stations in South Africa show long-term trends in turbidity, but there is no consistent trend. Turbidity in Germany appears to be more influenced by aerosols of non-local origin than in South Africa, where the aerosol load may be of more local origin. Long-term monthly averages ofÅngström's turbidity coefficient β over Germany range between 0.019 and 0.143, and long-term annual averages range between 0.064 and 0.116. Over South Africa, turbidity is noticeably lower: long-term monthly averaged β ranges between 0.004 and 0.071, and the long-term annually averaged β ranges between 0.013 and 0.047. When averaged across all stations in each of the respective countries, turbidity is, on average, between 2.6 and 5.8 times higher in Germany than in South Africa, depending on the time of year.The climate of South Africa is clearly more humid than Germany, although both countries have strong seasonal trends in humidity. South Africa has become more humid over the last several decades. The decrease in turbidity at stations in Germany appears to be due to a reduction in aerosol emissions and/or changes in climatic factors other than humidity.

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“…Wenxian [14] established a linear model for correlating direct transmittance to clearness index while several researchers developed quadratic models using direct transmittance to clearness index [2][3], [9][10], [15]. In order to generate an appropriate model for the study stations in addition to quadratic type model (model 1), two models based on the correlation between direct transmittance to clearness index: quadratic-exponential model (model 2) and linear-logarithmic (model 3) are proposed for all sky conditions and clear sky conditions (kt) in this research in the forms:…”

Section: Model Developmentmentioning

confidence: 99%

“…In spite of the enormous significance of Hb, there is no standard weather station capable to measure this radiation component in Nigeria and often there is no data available in the location of interest except National Aeronautics and Space Administration (NASA) atmospheric science data [1] among others satellite radiometric agencies across the globe. To overcome these problems, different estimation models have been proposed in different locations across the globe [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Considering the great importance of the Hb in the design of solarenergy systems requiring solar radiation tracking, such as highintensity solar cells and high-temperature heat engines, emphasis is often put on modeling the Hb component.…”

Section: Introductionmentioning

confidence: 99%

“…Parametric models require detailed information of atmospheric parameters or conditions such as type, amount and distribution of clouds consisting of could cover, precipitation water content, atmospheric turbidity, and sunshine fraction [3], [5][6][7], [11], [16][17][18]. On the other hand, decomposition models are used to estimate Hb from H and extraterrestrial solar radiation (Ho) data [2][3], [8][9][10], [14][15], [19]. Battles et al [20] recommended decomposition models, which are based on the correlation between the clearness index and direct fraction or direct transmittance where there are no precise information or data of atmospheric turbidity coefficient, precipitable water content and cloud cover.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of direct normal irradiance under various sky condi-tions in data sparse tropical ecological zones in Nigeria

Nwokolo

Ogbulezie

2017

IJAA

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In this study, models for estimating direct normal irradiance (Hb) under various sky conditions in data sparse tropical ecological zones in Nigeria were fitted. The evaluated values of clearness index indicate that the prevailing sky condition in the southern tropical zones is heavily overcast while the northern zones experience partly overcast under all sky conditions. From the analyses of the influences of clearness index on Hb, it was observed that higher values of Hb were recorded in the far north zone of Sahel savannah (FNZSS) of Sokoto while lower values were registered in the far south zone of mangrove swamp of Port Harcourt revealing an increasing trend from FSZMS to FNZSS due to the trends in cloudiness and associated atmospheric moisture with the movement through the Hadley cell calculation system along the equatorial line. The regression correlation models developed from the model performance test indicates that the proposed models could be used to estimate Hb accurately between latitude 4 to 10 o N, that is, mangroves swamp and Guinea savannah tropical zones in Nigeria and other locations with comparable sky conditions.

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Correlations for direct normal and global horizontal irradiation on a French Mediterranean site

Cited by 157 publications

References 15 publications

Using digital image processing to characterize the Campbell–Stokes sunshine recorder and to derive high-temporal resolution direct solar irradiance

Using digital image processing to characterize the Campbell–Stokes sunshine recorder and to derive high-temporal resolution direct solar irradiance

Comparison of aerosol and climate variability over Germany and South Africa

Estimation of direct normal irradiance under various sky condi-tions in data sparse tropical ecological zones in Nigeria

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