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Advances in Science and Research The open-access proceedings of the European Meteorological Society (EMS)

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Adv. Sci. Res., 13, 1-6, 2016
https://doi.org/10.5194/asr-13-1-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
 
02 Feb 2016
On the effective solar zenith and azimuth angles to use with measurements of hourly irradiation
P. Blanc and L. Wald MINES ParisTech – PSL Research University, Sophia Antipolis, France
Abstract. Several common practices are tested for assessing the effective solar zenith angle that can be associated to each measurement in time-series of in situ or satellite-derived measurements of hourly irradiation on horizontal surface. High quality 1 min measurements of direct irradiation collected by the BSRN stations in Carpentras in France and Payerne in Switzerland, are aggregated to yield time series of hourly direct irradiation on both horizontal and normal planes. Time series of hourly direct horizontal irradiation are reconstructed from those of hourly direct normal irradiation and estimates of the effective solar zenith angle by one of the six practices. Differences between estimated and actual time series of the direct horizontal irradiation indicate the performances of six practices. Several of them yield satisfactory estimates of the effective solar angles. The most accurate results are obtained if the effective angle is computed by two time series of the direct horizontal and normal irradiations that should be observed if the sky were cloud-free. If not possible, then the most accurate results are obtained from using irradiation at the top of atmosphere. Performances show a tendency to decrease during sunrise and sunset hours. The effective solar azimuth angle is computed from the effective solar zenith angle.

Citation: Blanc, P. and Wald, L.: On the effective solar zenith and azimuth angles to use with measurements of hourly irradiation, Adv. Sci. Res., 13, 1-6, https://doi.org/10.5194/asr-13-1-2016, 2016.
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Short summary
Time series of hourly measurements or modelled values of surface solar irradiation are increasingly available. Currently, no solar zenith and azimuth angles are associated to each measurement whereas such angles are necessary for handling the measured or modelled irradiations. A method is proposed to assess such angles with a great accuracy. It makes use of two modelled time-series that can be computed using the web site www.soda-pro.com for any site in the world.
Time series of hourly measurements or modelled values of surface solar irradiation are...
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