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Structure de la turbulence atmosphérique à proximité de la surface

Abstract : Understanding the structure of turbulence in the surface layer of the atmosphere is crucial for improving weather prediction. In this work, we rely on turbulence measurements collected by the sonic anemometers Observatory SIRTA and numerical simulations (large eddy simulations) in 3-D using the ARPS model taking into the interactions vegetation-atmosphere, to study the structure of atmospheric turbulence for different surface types (field, forest, buildings). Turbulence is approached statistically, with the calculation of mean variables such as turbulent flow, momentum and heat, or turbulent kinetic energy, and deterministically. In the latter case, we use a method of detecting coherent structures based on wavelet transform, to determine their properties such as their frequency of occurrence or their relative contribution to turbulent flow. The results of this thesis mainly show that despite the impact of complex terrain on the mean variables that are of turbulence flows or turbulent kinetic energy, the important properties of coherent structures (frequency of occurrence, duration and separation time, contribution to flow ...) appear independent of the terrain. This is because the coherent structures detected from time series of temperature and vertical velocity are representative of the active turbulence adjusts quickly to local conditions of the surface.
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Submitted on : Wednesday, July 21, 2010 - 9:49:53 AM
Last modification on : Wednesday, October 14, 2020 - 4:11:26 AM
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  • HAL Id : pastel-00005520, version 1

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Clément Fesquet. Structure de la turbulence atmosphérique à proximité de la surface. Sciences de l'ingénieur [physics]. Ecole Polytechnique X, 2008. Français. ⟨pastel-00005520⟩

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