Flux decomposition into coherent structures

Mahrt, L.; Gibson, Wayne

doi:10.1007/bf00122065

Cited by 59 publications

(28 citation statements)

References 37 publications

(37 reference statements)

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“…We also note that the close agreement between the wind and surface for these roll signatures along a given flight track of 300-800 s probably indicates some measure of the eddy inactivity [see Mahrt and Gibson, 1992] in that both the spectral data and coherence suggest "quasi-stable" wind speed modulations. Mourad [1996] provides discussion of such eddies evident within SAR and advanced very high resolution radiometer (AVHRR) wind row images that support this as well.…”

Section: Wavelet Analysismentioning

confidence: 78%

Measured changes in ocean surface roughness due to atmospheric boundary layer rolls

Vandemark¹,

Pd²,

Bailey³

et al. 2001

J. Geophys. Res.

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Section: Wavelet Analysismentioning

confidence: 78%

Measured changes in ocean surface roughness due to atmospheric boundary layer rolls

Vandemark¹,

Pd²,

Bailey³

et al. 2001

J. Geophys. Res.

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“…Walker, 1997) suggested that non-orthogonal Morlet wavelets are a suitable 'mother' for turbulence. Mahrt (1991a,b) and Mahrt and Gibson (1992) used an orthogonal basis transform (Haar wavelets). Here, Morlet 'mother' wavelets were chosen, because they are suitable not only for statistical analyses (variance and covariance), but also for pattern recognition in turbulence data (see, also, the next section).…”

Section: Developing a Wavelet Transform For Aircraft-based Turbulencementioning

confidence: 99%

Applying wavelet transforms to analyse aircraft‐measured turbulence and turbulent fluxes in the atmospheric boundary layer over eastern Siberia

Strunin

Hiyama

2004

Hydrological Processes

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Abstract:The wavelet spectral method was applied to aircraft-based measurements of atmospheric turbulence obtained during joint Russian-Japanese research on the atmospheric boundary layer near Yakutsk (eastern Siberia) in April-June 2000. Practical ways to apply Fourier and wavelet methods for aircraft-based turbulence data are described. Comparisons between Fourier and wavelet transform results are shown and they demonstrate, in conjunction with theoretical and experimental restrictions, that the Fourier transform method is not useful for studying non-homogeneous turbulence. The wavelet method is free from many disadvantages of Fourier analysis and can yield more informative results. Comparison of Fourier and Morlet wavelet spectra showed good agreement at high frequencies (small scales). The quality of the wavelet transform and corresponding software was estimated by comparing the original data with restored data constructed with an inverse wavelet transform. A Haar wavelet basis was inappropriate for the turbulence data; the 'mother' wavelet function recommended in this study is the Morlet wavelet. Good agreement was also shown between variances and covariances estimated with different mathematical techniques, i.e. through non-orthogonal wavelet spectra and through eddy correlation methods.

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“…Further, it is also believed that coherent structures are the agents responsible for the production and maintenance of strong flux fields in the PBL (e.g., McWilliams et al, 1996;Gerz et al, 1993;Mahrt and Gibson, 1992 …”

Section: Implications Of Grid Nesting For Coherent Structuresmentioning

confidence: 99%

A grid nesting method for large-eddy simulation of planetary boundary-layer flows

Sullivan

McWilliams

Moeng

1996

Boundary-Layer Meteorol

178

149

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A method for performing nested grid calculations with a large-eddy simulation code is described. A common numerical method is used for all meshes, and the grid architecture consists of a single outer or coarse grid, and nested or fine grids, which overlap in some common region. Inter-grid communication matches the velocity, pressure and potential temperature fields in the overlap region. Resolved and sub-grid scale (SGS) turbulent fluxes and kinetic energy on the fine grid are averaged to the coarse grid using a conservation rule equivalent to Germano's identity used to develop dynamic SGS models.Simulations of a slightly convective, strong shear planetary boundary layer were carried out with varying surface-layer resolutions. Grid refinements in the (z, y, z) directions of up to (5, 5, 2) times were employed. Two-way interaction solutions on the coarse and fine meshes are successfully matched in the overlap region on an instantaneous basis, and the turbulent motions on the fine grid blend smoothly into the coarse grid across the grid interface. With surface-layer grid nesting, significant increases in resolved eddy fluxes and variances are found. The energy-scale content of the vertical velocity, and hence vertical turbulent fluxes, appear to be most influenced by increased grid resolution. Vertical velocity spectra show that the dominant scale shifts towards higher wavenumbers (smaller scales) and the magnitude of the peak energy is increased by more than a factor of 3 with finer resolution. Outside of the nested region the average heat and momentum fluxes and spectra are slightly influenced by the fine resolution in the surface layer. From these results we conclude that fine resolution is required to resolve the details of the turbulent motions in the surface layer. At the same time, however, increased resolution in the surface layer does not appreciably alter the ensemble statistics of the resolved and SGS motions outside of the nested region.

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Flux decomposition into coherent structures

Cited by 59 publications

References 37 publications

Measured changes in ocean surface roughness due to atmospheric boundary layer rolls

Measured changes in ocean surface roughness due to atmospheric boundary layer rolls

Applying wavelet transforms to analyse aircraft‐measured turbulence and turbulent fluxes in the atmospheric boundary layer over eastern Siberia

A grid nesting method for large-eddy simulation of planetary boundary-layer flows

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