A New Approach for the Determination of Horizontal Wind Direction Fluctuations

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  • 1 IBERDROLA, Department of Nuclear Engineering, Madrid, Spain
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Abstract

A new method to determine horizontal wind direction fluctuations σθ is presented based on the hypothesis of a Gaussian distribution of wind direction that gradually moves to a circular, uniform distribution under near-clam conditions. A theoretical formulation for σθ, the persistence of wind and the total horizontal standard deviation σ, is provided and supported by experimental observation both in a complex terrain valley site and in an open grassland spot in Spain. Comparisons of the proposed model with observations yielded a fairly good agreement making the theoretical functions a straightforward procedure for use in atmospheric dispersion calculations. The method also provides insights on either the residual diffusivity in near-calm conditions or the maximal observable standard deviation.

Abstract

A new method to determine horizontal wind direction fluctuations σθ is presented based on the hypothesis of a Gaussian distribution of wind direction that gradually moves to a circular, uniform distribution under near-clam conditions. A theoretical formulation for σθ, the persistence of wind and the total horizontal standard deviation σ, is provided and supported by experimental observation both in a complex terrain valley site and in an open grassland spot in Spain. Comparisons of the proposed model with observations yielded a fairly good agreement making the theoretical functions a straightforward procedure for use in atmospheric dispersion calculations. The method also provides insights on either the residual diffusivity in near-calm conditions or the maximal observable standard deviation.

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