Monthly ratios of PAR to global solar radiation measured at northern Tibetan Plateau, China

Li, Ren; Zhao, Lin; Ding, Yongjian; Wang, Sheng; Ji, Guoliang; Xiao, Yao; Liu, Guangyue; Sun, Lianfeng

doi:10.1016/j.solener.2010.03.005

Cited by 53 publications

(41 citation statements)

References 31 publications

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“…4, PAR/H is expected to also have an inverse relationship with k t , i.e. k t explains part of the variations in H. This has been shown in several studies as a logarithmic relationship (Alados et al 1996;Jacovides et al 2007) or inverse linear relationship within certain range of k t (Li et al 2010). The improvement in the accuracy of estimation of PAR with k t is also in alignment with the study by Hu and Wang (2014).…”

Section: Estimation Of Parsupporting

confidence: 72%

Photosynthetically active radiation and comparison of methods for its estimation in equatorial Singapore

Tan

Ismail

2015

Theor Appl Climatol

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Photosynthetically active radiation (PAR) is an important input variable for urban climate, crop modelling and ecosystem services studies. Despite its importance, only a few empirical studies have been conducted on PAR, its relationship to global solar radiation and sky conditions and its estimation in the tropics. We report in this study, the characterisation of PAR in Singapore through direct measurements and development of models for its estimation using input variables of global solar radiation (H), photometric radiation (L), clearness index (k t ) and sky view factor (SVF). Daily PAR showed a good correlation with daily H and had a comparatively small seasonal variation in PAR due to Singapore's equatorial position. The ratio of PAR to H (PAR/H) showed a slight depression in midyear from May to August, which correlated well with seasonal patterns in rainfall over the study period. Hourly PAR/H increased throughout the day. Three empirical models developed in this study were able to predict daily PAR satisfactorily, with the most accurate model being one which included both H and k t as independent variables. A regression model for estimation of PAR under shaded conditions using SVF produced satisfactory estimation of daily PAR but was prone to high mean percentage error at low PAR levels.

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Section: Estimation Of Parsupporting

confidence: 72%

Photosynthetically active radiation and comparison of methods for its estimation in equatorial Singapore

Tan

Ismail

2015

Theor Appl Climatol

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“…Clearness index k T is the ratio of R glb to the extraterrestrial solar radiation R 0 (W m −2 ) (Tsubo and Walker, 2005;Li et al, 2010;Aguiar et al, 2012). R 0 is calculated with the equation of Kondo (1994) as …”

Section: Calculation Of Solar Radiation (R S ) and Photosyntheticallymentioning

confidence: 99%

“…Although many authors (e.g., Aguiar et al, 2012;Jacovides et al, 2003;Li et al, 2010) reported dependence on site or season, the reasons for any dependence of P E /R S on Â have been unclear. Because this dependence is often described implicitly in diurnal variations, we first show the diurnal variations of P E /R S .…”

Section: Dependence Of P E /R S On Solar Zenith Angle (â)mentioning

confidence: 99%

“…Various values for P E /R S have been reported (e.g., Blackburn and Proctor, 1983;Jacovides et al, 2003;Li et al, 2010;McCree, 1966;Papaioannou et al, 1993;Rao, 1984;Stigter and Musabilha, 1982;Tsubo and Walker, 2005). Furthermore, various values for P P /R S have been reported (e.g., Alados et al, 1996;Britton and Dodd, 1976;Finch et al, 2004;Ge et al, 2011;Howell et al, 1983;Jacovides et al, 2007;Meek et al, 1984;Udo and Aro 1999;Weiss and Norman, 1985).…”

Section: Introductionmentioning

confidence: 99%

“…Some authors have indicated that PAR/R S increases with Â (e.g., Meek et al, 1984;Udo and Aro 1999), whereas some have also indicated the opposite (e.g., Ge et al, 2011;González and Calbó, 2002). Moreover, some authors have indicated that the relationship changes based on the site or season (e.g., Aguiar et al, 2012;Jacovides et al, 2003;Li et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On the stability of radiometric ratios of photosynthetically active radiation to global solar radiation in Tsukuba, Japan

Akitsu

Kume

Hirose

et al. 2015

Agricultural and Forest Meteorology

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Reconstruction of daily photosynthetically active radiation and its trends over China

et al. 2013

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[1] Photosynthetically active radiation (PAR) is widely required in ecological studies, but it is not routinely measured at China Meteorological Administration (CMA) stations. In this study, a PAR model is utilized to estimate daily PAR from routine meteorological parameters (air temperature, air pressure, relative humidity, and sunshine duration) at CMA stations. The estimate is evaluated against measurements at 10 Chinese Ecosystem Research Network (CERN) stations. The model can produce PAR with mean bias errors of À2.4 W m À2, root mean square errors of 14.0 W m À2, and correlation coefficient (R) of 0.92 at all CERN stations. Comparison with a locally calibrated model indicates that the estimate has a comparable or even higher accuracy than the local model calibrated with CERN data. Another evaluation at an independent site further indicates that our estimate has higher accuracy than the local model at stations independent of CERN. Finally, a 50 year data set of daily PAR at 716 CMA stations over China is reconstructed by the validated model, and its climatology and long-term variations over China are analyzed. The data set would substantially contribute to ecological studies in China.

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Monthly ratios of PAR to global solar radiation measured at northern Tibetan Plateau, China

Cited by 53 publications

References 31 publications

Photosynthetically active radiation and comparison of methods for its estimation in equatorial Singapore

Photosynthetically active radiation and comparison of methods for its estimation in equatorial Singapore

On the stability of radiometric ratios of photosynthetically active radiation to global solar radiation in Tsukuba, Japan

Reconstruction of daily photosynthetically active radiation and its trends over China

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