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Atmos. Meas. Tech., 11, 3131-3144, 2018
https://doi.org/10.5194/amt-11-3131-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
31 May 2018
Effects of temporal averaging on short-term irradiance variability under mixed sky conditions
Gerald M. Lohmann1 and Adam H. Monahan2 1Energy Meteorology Group, Institute of Physics, Oldenburg University, Oldenburg, Germany
2School of Earth and Ocean Sciences, University of Victoria, Victoria, Canada
Abstract. Characterizations of short-term variability in solar radiation are required to successfully integrate large numbers of photovoltaic power systems into the electrical grid. Previous studies have used ground-based irradiance observations with a range of different temporal resolutions and a systematic analysis of the effects of temporal averaging on the representation of variability is lacking. Using high-resolution surface irradiance data with original temporal resolutions between 0.01 and 1 s from six different locations in the Northern Hemisphere, we characterize the changes in representation of temporal variability resulting from time averaging. In this analysis, we condition all data to states of mixed skies, which are the most potentially problematic in terms of local PV power volatility. Statistics of clear-sky index k* and its increments Δk*τ (i.e., normalized surface irradiance and changes therein over specified intervals of time) are considered separately. Our results indicate that a temporal averaging time scale of around 1 s marks a transition in representing single-point irradiance variability, such that longer averages result in substantial underestimates of variability. Higher-resolution data increase the complexity of data management and quality control without appreciably improving the representation of variability. The results do not show any substantial discrepancies between locations or seasons.
Citation: Lohmann, G. M. and Monahan, A. H.: Effects of temporal averaging on short-term irradiance variability under mixed sky conditions, Atmos. Meas. Tech., 11, 3131-3144, https://doi.org/10.5194/amt-11-3131-2018, 2018.
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Short summary
Using high-resolution surface irradiance data with original temporal resolutions between 0.01 s and 1 s from six different locations in the Northern Hemisphere, we characterize the changes in representation of temporal variability resulting from time averaging. Our results indicate that a temporal averaging time scale of around 1 s marks a transition in representing single-point irradiance variability, such that longer averages result in substantial underestimates of variability.
Using high-resolution surface irradiance data with original temporal resolutions between 0.01 s...
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