Estimating clear-sky beam irradiation from sunshine duration

Power, Helen C.

doi:10.1016/s0038-092x(01)00049-4

Cited by 41 publications

(20 citation statements)

References 23 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%

“…For example, many authors relate SD for a period of time with direct and global (the sum of the solar direct and diffuse contributions) irradiance with the use of the so-called Ångström-Prescott type formulas (e.g., Sears et al, 1981;Benson et al, 1984;Martínez-Lozano et al, 1984;Stanhill, 1998;Power, 2001;Suehrcke, 2000;Bakirci, 2009), which were first proposed by Ångström (1924) and further A. Sanchez-Romero et al: Using digital image processing to characterize the CSSR 185 modified by Prescott (1940). In addition, R. Jaenicke and L. Helmes developed a series of pioneering studies presenting a method to determine atmospheric turbidity from SD records and cloud cover data (Jaenicke and Kasten, 1978;Helmes and Jaenicke, 1984, 1985, 1986) that has recently aroused interest (for a review, see Sanchez-Romero et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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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%

Section: Introductionmentioning

confidence: 99%

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%

“…EstimatingH bc from Equation (3) will propagate the errors associated withs,H , andH d . However, Power (2001c) demonstrated that Equation (3) provides reliable estimates of monthly averaged potential daily clear-sky beam irradiation. Gueymard's algorithm for estimating precipitable water has been shown to provide monthly estimates of w that are in close agreement with w derived from radiosonde observations (Gueymard, 1994).…”

Section: Error and Sensitivity Analysesmentioning

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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“…A maioria dos estudos realizados com essa metodologia no Brasil enfocou apenas na estimativa da radiação global na horizontal (Blanco & Sentelhas, 2002;Tiba et al, 2005;Dornellas et al, 2006;Escobedo et al, 2007;Carvalho et al, 2011, entre outros). Existem alguns trabalhos desenvolvidos com avaliações para as componentes da radiação (Maduekwe & Chendo, 1995;Gopinathan & Soler, 1996;Alnaser & Al-Attar, 1999;Vartiainen, 2000;Power, 2001;Robledo & Soler, 2002;Bashahu, 2003;Mediavilla et al, 2005;Boland et al, 2008;Noorian et al, 2008;Koussa et al, 2009); todavia, em sua grande maioria não contemplam estimativas para superfícies inclinadas e ainda no Brasil são mais escassas (Drechmer & Ricieri, 2006;Escobedo et al, 2007).…”

Section: Introductionunclassified

Estimativas das radiações direta e difusa em superfícies inclinadas com base na razão de insolação

Souza

Escobedo

2013

Agraria

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RESUMOForam obtidas e avaliadas equações estatísticas com agrupamentos de dados anuais, sazonais e mensais, para estimativa das componentes direta e difusa da radiação solar com base na razão de insolação (razão entre brilho solar e fotoperíodo) incidente na horizontal e em superfícies inclinadas a 12,85, 22,85 e 32,85° voltadas para o Norte, em Botucatu, SP. Empregaram-se as razões entre as duas componentes e a radiação no topo da atmosfera, em uma base de dados cujas medidas nas três inclinações ocorreram em diferentes períodos (22,85°: 04/1998 a 07/2001; 12,85°: 08/2011 a 02/2003 e 32,85°: 03/2003 a 12/2007) e concomitantes com as medidas na horizontal e com a insolação. As correlações apresentaram comportamentos linear e polinomial de segundo grau para a direta e a difusa, com maiores coeficientes de determinação em períodos com baixa variação da nebulosidade. Os maiores valores da radiação direta e difusa foram encontrados no inverno e no verão, respectivamente. O aumento do ângulo de inclinação diminuiu o desempenho das equações de estimativa em todos os agrupamentos de dados com aumento do espalhamento e diminuição do ajustamento. As equações mensais apresentaram desempenhos superiores para as duas componentes.Palavras-chave: energia solar, indicativos estatísticos, modelo Angströn-Prescott, transmissividade atmosférica Estimates of direct and diffuse radiation incident on inclined surfaces based on ratio of sunshine duration ABSTRACTStatistical equations were obtained and evaluated with annual, seasonal and monthly data groupings for estimates of direct and diffuse components of solar radiation based on the sunshine duration (ratio of sunshine and photoperiod) incident on horizontal and inclined surfaces to 12.85, 22.85 and 32.85° with facing to North, in Botucatu, SP. The ratios between the two components and radiation at the top of the atmosphere were used, in a database whose inclinations were measured in three different periods (22.85°: 04/1998 to 07/2001; 12.85°: 08/2011 to 02/2003; and 32.85°: 03/2003 to 12/2007) and concomitant with horizontal measures and sunshine duration. The correlations showed a linear and second degree polynomial behavior for the direct and diffuse radiation, with higher coefficients of determination in periods of low variation in the coverage of the sky (cloudiness). The highest values of the direct and diffuse radiation were found in winter and summer, respectively for all surfaces evaluated. The increase in the inclination angle decreased the performance of equations in all groups of data with increase in scattering and decrease in index of the adjustment, however, the monthly equations allowed better performance for the two components.

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Estimating clear-sky beam irradiation from sunshine duration

Cited by 41 publications

References 23 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

Estimativas das radiações direta e difusa em superfícies inclinadas com base na razão de insolação

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