Quantifying Organization of Atmospheric Turbulent Eddy Motion Using Nonlinear Time Series Analysis |
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| Authors: | Karen H Wesson Gabriel G Katul Mario Siqueira |
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| Institution: | (1) School of the Environment, Duke University, Box 90328, Durham, NC, 27708-0328;(2) The Cadmus Group, Inc., 6330 Quadrangle Drive, Suite 180, Chapel Hill, NC;(3) Department of Civil and Environmental Engineering, Duke University, Durham, NC, 27708, U.S.A |
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| Abstract: | Using three methods from nonlinear dynamics, we contrast the level of organization inthe vertical wind velocity (w) time series collected in the atmospheric surface layer(ASL) and the canopy sublayer (CSL) for a wide range of atmospheric stability ( )conditions. The nonlinear methods applied include a modified Shannon entropy, waveletthresholding, and mutual information content. Time series measurements collected overa pine forest, a hardwood forest, a grass-covered forest clearing, and a bare soil, desertsurface were used for this purpose. The results from applying all three nonlinear timeseries measures suggest that w in the CSL is more organized than that in the ASL, and that as the flows in both layers evolve from near-neutral to near-convective conditions, the level of organization increases. Furthermore, we found that the degree of organization in w associated with changes in is more significant than the transition from CSL to ASL. |
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| Keywords: | Canopy turbulence Mutual information content Nonlinear time series analysis Organized motion Shannon entropy Wavelet thresholding |
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