Abstract
A simple temporal and spatial analysisis done on wind speed and direction data from a number ofmeteorological towers separated by distances between roughly 1 and 100 kilometres. The analysis is done in the context of expected model error in wind energy calculations. The study first uses single point statistics to show the evolution of mean values with time. It is shown that strong seasonal signals are present and that stable means are achieved only after averaging periods of a year or more. The study then uses discrete Fourier transforms to show that significant amounts of spectral energy reside in modes with periods of a few days to less than a day. Frequency dependent cross correlation values are then derived and used to show how correlation between towers diminishes with increasing frequency. The mechanism responsible for this diminished correlation is shown through the comparison of cross-correlation phase as a function of frequency and its relationship to distance between towers. Error in wind energy estimates are shown to be strongly related to correlation and therefore distance over which the prediction is made. In summary, much of the inaccuracy in modelling flow in the context of wind energy calculations is due to a lack of scale separation between the deterministic part of the flow, which is well modelled, and that part of the flow that is stochastic at the length and time scales modelled.
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References
Ayotte, K. W. and Taylor, P. A.: 1995, ‘A Mixed Spectral Finite Difference 3D Model of Neutral Planetary Boundary Layer Flow over Topography’, J. Atmos. Sci. 52, 3523–3537.
Ayotte, K. W., Xu, D., and Taylor, P. A.: 1994, ‘The Impact of Different Turbulence Closures on Predictions of the Mixed-Spectral Finite-Difference Model for Flow over Topography’, Boundary-Layer Meteorol. 68, 1–33.
Beljaars, A. C. M., Walmsley, J. L., and Taylor, P. A.: 1987, ‘A Mixed-Spectral Finite-Difference Model for Neutrally Stratified Boundary Layer Flow over Roughness Changes and Topography’, Boundary-Layer Meteorol. 38, 273–303.
Bowen, A. J. and Mortensen, N. G.: 1996, ‘Exploring the Limits ofWASP: TheWind Atlas Analysis and Application Program’, in Proceedings of 1996 European Union Wind Energy Conference, 20–24 May, 1996, Goteborg, Sweden.
Hewer, F. E.: 1998, ‘Non-Linear Numerical Predictions of Flow over an Isolated Hill of Moderate Slope’, Boundary-Layer Meteorol. 87, 381–408.
Hunt, J. C. R, Leibovich, S., and Richards, K. J.: 1988, ‘Turbulent Shear Flow over Low Hills’, Quart. J. Roy. Meteorol. Soc. 114, 1435–1471.
Mason, P. J. and King, J. C.: 1985, ‘Measurements and Predictions of Flow and Turbulence over an Isolated Hill of Moderate Slope’, Quart. J. Roy. Meteorol. Soc. 111, 617–640.
Petersen, E. L., Mortensen, N. G., and Landberg, L.: 1996, ‘Measurement and Modelling in Complex Terrain’, in Proceedings of 1996 European Union Wind Energy Conference, 20–24 May, 1996, Goteborg, Sweden.
Press, W. H., Flannery, B. P., Teukolsky, S. A., and Vetterling, W. T.: 1988, Numerical Recipes in C The Art of Scientific Computing, Cambridge University Press, New York, 735 pp.
Salmon, J. R., Teunissen, H. W., Mickle, R. E., and Taylor, P. A.: 1988, ‘The Kettles Hill Project: Field Observations. Wind-Tunnel Simulations and Numerical Model Predictions for Flow over a Low Hill’, Boundary-Layer Meteorol. 43, 309–343.
Stull, R. B.: 1993, ‘Review of Non-Local Mixing in Turbulent Atmospheres: Transilient Turbulence Theory’, Boundary-Layer Meteorol. 62, 21–96.
Taylor, P. A. and Teunissen, H. W.: 1987, ‘The Askervein Hill Project: Overview and Background Data’, Boundary-Layer Meteorol. 39, 15–39.
Taylor, P. A., Mason, P. J., and Bradley, E. F.: 1987, ‘Boundary Layer Flow over Lower Hills’, Boundary-Layer Meteorol. 39, 107–132.
Troen, I. and Mahrt, L.: 1986, ‘A Simple Model of the Atmospheric Boundary Layer: Sensitivity to Evaporation’, Boundary-Layer Meteorol. 37, 129–148.
Troen, I. and Petersen, E. L.: 1989, European Wind Atlas, Risø National Laboratory, Rø skilde, Denmark, ISBN 87-550-1482-8, 656 pp.
Walmsley, J. L. and Bagg, D. L.: 1978, ‘A Method of Correlating Wind Data between Stations with Application to the Alberta Oil Sands’, Atmos. Ocean 16, 333–347.
Wood, N.: 2000, ‘Wind Flow over Complex Terrain: A Historical Perspective and the Prospect for Large-Eddy Modelling’, Boundary-Layer Meteorol. 96, 11–32.
Wood, N. and Mason, P. J.: 1993, ‘The Pressure Force Induced by Neutral, Turbulent Flow over Hills’, Quart. J. Roy. Meteorol. Soc. 119, 1233–1267.
Xu, D. and Taylor, P. A.: 1992, ‘A Non-Linear Extension of the Mixed-Spectral Finite-Difference Model for Neutrally Stratified Turbulent Flow over Topography’, Boundary-Layer Meteorol. 59, 177–186.
Xu, D., Ayotte, K.W., and Taylor, P. A.: 1994, ‘Development of a Non-Linear Mixed Spectral Finite-Difference Model for Turbulent Boundary-Layer Flow over Topography’, Boundary-Layer Meteorol. 70, 341–367.
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Ayotte, K.W., Davy, R.J. & Coppin, P.A. A Simple Temporal and Spatial Analysis of Flow in Complex Terrain in the Context of Wind Energy Modelling. Boundary-Layer Meteorology 98, 275–295 (2001). https://doi.org/10.1023/A:1026583021740
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DOI: https://doi.org/10.1023/A:1026583021740