Sky luminance distribution in the North of Iberian Peninsula during winter

Torres, José Luis; Blas, M. De; Garcı́a, A.; Gracia, Álvaro de; Francisco, A. de

doi:10.1016/j.jastp.2010.07.001

Cited by 21 publications

(9 citation statements)

References 13 publications

(24 reference statements)

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“…The Tregenza method appears to be more stable and effective, as it takes these potential issues into consideration. The method has been applied successfully by many researchers (Ng et al 2007;Torres et al 2010aTorres et al , 2010bSuárez-García et al 2018). As shown in Figure 5 (Zi 2020), the sky hemisphere was divided into 145 sky elements.…”

Section: Sky Classification With Tregenza Methodsmentioning

confidence: 99%

“…), Singapore (1.5°N, 103.78°E), and China (Hong Kong 22.31°N, 114.21°E; Beijing 39.97°N, 116.4°E),etc. (Bartzokas et al 2003(Bartzokas et al , 2005Markou et al 2005;Ferraro, Mele, and Marinelli 2011;Torres et al 2010aTorres et al , 2010bSuárez-García et al 2018;Janjai and Palon 2011;Mettanant, Chaiwiwatworakul, and Chirarattananon 2017;Wittkopf and Soon 2007;Li, Lau, and Lam 2004;Ng et al 2007;Luo et al 2015). However, sky luminance research has been carried out in very few areas in Asia.…”

Section: Introductionmentioning

confidence: 99%

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Sky type classification in Harbin during winter

Sun

Han

2020

Journal of Asian Architecture and Building Engineering

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Sky type classification is a significant element in daylight simulation. As a "winter city", the daylight climate of Harbin is distinctive, and there is therefore a particular need to determine the most appropriate sky models to establish sky luminance distribution in the city and thereby improve the accuracy of daylight simulations. To determine the closest sky type to that of Harbin during winter, sky luminance data consisting of 145 sky elements were collected by a sky scanner at 10 min intervals from June 2018 to February 2019. The sky luminance data were compared with the 15 standard sky definitions, varying from overcast sky to clear sky, proposed by the Commission International de l' Eclairage (CIE). The sky with the lowest root-meansquare-error was selected as the most appropriate sky type. The results show that clear skies prevail in Harbin during winter, with an occurrence of 70.56%. The dominant sky type is type 12, with an occurrence of 48.57%, followed by types 11, 10, and 8 with occurrences of 17.67%, 5.81%, and 5.36% respectively. The sum of the occurrences of these four sky types exceeds 77%, which means that they can be regarded as generally representative of Harbin's skies during winter.

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Section: Sky Classification With Tregenza Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sky type classification in Harbin during winter

Sun

Han

2020

Journal of Asian Architecture and Building Engineering

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“…In 2003, the International Commission on Illumination (Commission Internationale de L'Éclairage or CIE) defined 15 standard sky types, five categorized as clear, five as partial cloudy, and five as overcast skies. In several works, it was concluded that the CIE standard sky classification adequately represented empirical sky conditions [34][35][36][37][38][39][40]. Sky types of the same category have the same well-defined sky luminance patterns that easily yield the solar irradiance and daylight illuminance on the surfaces of interest through simple mathematical expressions [41].…”

Section: Introductionmentioning

confidence: 99%

Photosynthetic Active Radiation, Solar Irradiance and the CIE Standard Sky Classification

et al. 2020

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Plant growth is directly related to levels of photosynthetic photon flux density, Qp. The improvement of plant-growth models therefore requires accurate estimations of the Qp parameter that is often indirectly calculated on the basis of its relationship with solar irradiation, RS, due to the scarcity of ground measurements of photosynthetic photon flux density. In this experimental campaign in Burgos, Spain, between April 2019 and January 2020, an average value of the Qp/Rs ratio is determined on the basis of measurements at ten-minute intervals. The most influential factor in the Qp/Rs ratio, over and above any daily or seasonal pattern, is the existence of overcast sky conditions. The CIE standard sky classification can be used to establish an unequivocal characterization of the cloudiness conditions of homogeneous skies. In this study, the relation between the CIE standard sky type and Qp/Rs is investigated. Its conclusions were that the Qp/Rs values, the average of which was 1.93±0.15 μmol·J−1, presented statistically significant differences for each CIE standard sky type. The overcast sky types presented the highest values of the ratio, while the clear sky categories presented the lowest and most dispersed values. During the experimental campaign, only two exceptions were noted for covered and partial covered sky-type categories, respectively, sky types 5 and 9. Their values were closer to those of categories classified as clear sky according to the CIE standard. Both categories presented high uniformity in terms of illumination.

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“…Sky luminance can be measured by using a sky scanner. Ideally, information on sky luminance should be obtained from a dense network of sky scanners, but due to costs, only a few instruments are routinely deployed in most parts of the world, and limited works on sky luminance measurements have been reported [5][6][7][8]. As a result, sky luminance has to be obtained from model calculations.…”

Section: Introductionmentioning

confidence: 99%

A Satellite-Based Sky Luminance Model for the Tropics

Janjai

2013

International Journal of Photoenergy

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This paper presents a sky luminance model for the tropics. The model is mathematically expressed as a multiplication of two functions. These areφ, which is a function of the zenith angle of a sky element and solar zenith angle, andf, which is a function of the angle between the sky element and the sun. To obtain the analytical forms of these functions, the sky luminance data collected at Nakhon Pathom (13.82°N, 100.04°E), Thailand, during a four-year period were analyzed. Additionally, satellite-derived cloud index at the position of the sky luminance measurements during the same period was estimated. Based on values of the cloud index, the skies were classified into 10 types, from clear to overcast skies. By using appropriate grouping and mathematical operation of the sky luminance data, the values of the two functions were obtained and then fitted with empirical equations. The multiplication of these equations gives the final form of the sky luminance model. To validate the model, it was used to calculate the relative sky luminance at other three sites in the tropics. It was found that values of relative sky luminance calculated from the model and those obtained from the measurements were in reasonable agreement.

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Sky luminance distribution in the North of Iberian Peninsula during winter

Cited by 21 publications

References 13 publications

Sky type classification in Harbin during winter

Sky type classification in Harbin during winter

Photosynthetic Active Radiation, Solar Irradiance and the CIE Standard Sky Classification

A Satellite-Based Sky Luminance Model for the Tropics

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