An attempt at estimating solar radiation at South African sites which measure air temperature only

Clemence, B. S.E.

doi:10.1080/02571862.1992.10634601

Cited by 7 publications

(3 citation statements)

References 7 publications

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“…The DR is generally higher on clear days and lower under clouded sky (e.g., Cengiz et al, 1981). Therefore, in this method, DR surrogates as an index of cloudiness and humidity (Cengiz et al, 1981; Clemence, 1992).…”

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Effect of Time of Temperature Observation and Estimation of Daily Solar Radiation for the Northern Great Plains, USA

Mahmood

Hubbard

2002

Agronomy Journal

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Daily incident solar radiation is an important input for numerous crop growth simulation models. However, lack of recorded solar radiation is a significant impediment for most crop–climate studies. The present study aimed to overcome the problem of sparse historical data of solar radiation over the northern Great Plains. The approach was to develop a physically based solar radiation model wherein estimates were possible with minimum input data. In addition, this study investigates impacts of time of observation bias on the model formulation. The proposed model (M‐H) requires measured daily range of air temperature (maximum minus minimum) and estimated daily clear‐sky solar radiation. Daily weather data (including solar radiation measurements) for nine stations with observations from 1990 through 1998 were used for formulation of the final model. To determine potential bias associated with the reporting time, three times—0800, 1600, and 2400 h—were tested. Based on superior performance, the solar radiation model formulated with 2400‐h reporting time data from Akron, CO, was selected for the whole region. The model underestimated high values. Local‐scale advection and frontal passage were apparently responsible for this bias. This proposed model was also compared with two forms of the Bristow–Campbell (B‐C) model. Both of these forms show significant improvement for 2400‐h observation time. One particular form of the B‐C model performs slightly better than the model proposed here. However, it also underestimates high values like the M‐H model and shows slight regional bias. This study finds that, overall, the M‐H model is more stable than the B‐C model.

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Effect of Time of Temperature Observation and Estimation of Daily Solar Radiation for the Northern Great Plains, USA

Mahmood

Hubbard

2002

Agronomy Journal

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“…At least 20 years of rainfall and 10 years of historic temperature data are required in order to get a reliable simulation. The CLIMGEN weather data generator was assessed at South African sites by Clemence (1997), who showed the estimations to be satisfactory. The SWB model requires weather, soil, vegetation, irrigation water quality and management input data.…”

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confidence: 99%

Soil Water Retention Properties as the Key Driver for Rehabilitation

Hattingh¹,

Viljoen²

2006

Proceedings of the International Conference on Mine Closure

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“…Sources of solar radiation data typically report solar radiation values in terms of monthly averages, rather than short timestep values, and tend to provide generalized maps of the region, rather than data for discrete locations. Schulze et al, (1992) provide detailed maps of monthly solar radiation, using a temperature-based algorithm from Clemence (1992). It is important to note that monthly data, while useful for some applications, are not suitable for accurate modelling of solar-driven energy processes.…”

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confidence: 99%

SASRAD: An hourly-timestep solar radiation database for South Africa

Ciolkosz

2009

J. energy South. Afr.

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A methodology is presented for the correction and filling of solar radiation data at sites within South Africa, with the aim of creating a continuous, hourly-timestep dataset for multiple locations. Data from twenty sites, collected by the Agricultural Research Council, are analysed with regard to the amount of data requiring offset or multiplier adjustment, as well as the amount of bad data. A range correction algorithm is implemented based on the 90th percentile (10% exceedance) hourly irradiance, as a function of site latitude and elevation. The resulting, corrected data set is given the title: South African Solar Radiation Database (SAS-RAD). Comparisons are made with two other solar radiation datasets, the South African Atlas of Agrohydrology and Climatology, and a limited set of older historical data from the South African Weather Service (SAWS).Results indicate that the SASRAD dataset matches well with other datasets, with major discrepancies apparently due to problems with the other data sets, rather than the SASRAD data. The Coefficient of Multiple Determination (R 2 ) between the Atlas and SASRAD for monthly radiation is 0.927, and the mean error between three of the SASRAD sites and the corresponding SAWS data is 1.1 MJ m -2 d -1 . The fraction of data requiring correction varied from 11% to 100%, depending on the site. The range correction algorithm was successful at correcting data that had been subject to incorrect calibration, and did not remove annual trends in mean radiation levels.

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An attempt at estimating solar radiation at South African sites which measure air temperature only

Cited by 7 publications

References 7 publications

Effect of Time of Temperature Observation and Estimation of Daily Solar Radiation for the Northern Great Plains, USA

Effect of Time of Temperature Observation and Estimation of Daily Solar Radiation for the Northern Great Plains, USA

Soil Water Retention Properties as the Key Driver for Rehabilitation

SASRAD: An hourly-timestep solar radiation database for South Africa

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