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Série Boundary-Layer Meteorology
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Boundary-Layer Meteorology, Vol.77 No.1. E-epsilon modelling of turbulent air flow downwind of a model forest edge / J. Liu
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.77 No.1 Titre : E-epsilon modelling of turbulent air flow downwind of a model forest edge Type de document : articles et extraits Auteurs : J. Liu, Auteur ; T.A. Black, Auteur ; J. M. Chen, Auteur ; M.D. Novak, Auteur Année de publication : 1996 Importance : p.21-44 ISBN/ISSN/EAN : 0006-8314 Langues : Français (fre) Résumé : A two-dimensional E- model, which included the effects of plant-atmosphere interaction, was used to simulate air flow downwind of forest edges for the purpose of predicting the microclimate in forest openings. A suitable set of wall functions was selected to consider the aerodynamic effects of the ground in the opening. The model with discretization and parameter schemes was validated using a set of data from a wind-tunnel experiment. The simulated wind speed and turbulence kinetic energy closely agreed with the measured values. After validation, the model was used to predict eddy diffusivity in the lee of the forest edge. The modelled spatial distribution of the eddy diffusivity agreed in general with that calculated using wind-tunnel measurements. The usefulness and limitations of the E- model are discussed.
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.77 No.1. E-epsilon modelling of turbulent air flow downwind of a model forest edge [articles et extraits] / J. Liu, Auteur ; T.A. Black, Auteur ; J. M. Chen, Auteur ; M.D. Novak, Auteur . - 1996 . - p.21-44.
ISSN : 0006-8314
Langues : Français (fre)
Résumé : A two-dimensional E- model, which included the effects of plant-atmosphere interaction, was used to simulate air flow downwind of forest edges for the purpose of predicting the microclimate in forest openings. A suitable set of wall functions was selected to consider the aerodynamic effects of the ground in the opening. The model with discretization and parameter schemes was validated using a set of data from a wind-tunnel experiment. The simulated wind speed and turbulence kinetic energy closely agreed with the measured values. After validation, the model was used to predict eddy diffusivity in the lee of the forest edge. The modelled spatial distribution of the eddy diffusivity agreed in general with that calculated using wind-tunnel measurements. The usefulness and limitations of the E- model are discussed.
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Code-barres Cote Support Localisation Section Disponibilité ART-6791-0 ART Document imprimé Bureau chercheur Bureau de ANSELMET, Fabien Disponible Boundary-Layer Meteorology, Vol.78 No.3-4. Coherent eddies and turbulence in vegetation canopies : the mixing layer analogy / M.R. Raupach
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.78 No.3-4 Titre : Coherent eddies and turbulence in vegetation canopies : the mixing layer analogy Type de document : articles et extraits Auteurs : M.R. Raupach, Auteur ; Y. Brunet, Auteur ; J. J. Finnigan, Auteur Année de publication : 1996 Importance : p.351-382 ISBN/ISSN/EAN : 0006-8314 Langues : Français (fre) Résumé : This paper argues that the active turbulence and coherent motions near the top of a vegetation canopy are patterned on a plane mixing layer, because of instabilities associated with the characteristic strong inflection in the mean velocity profile. Mixing-layer turbulence, formed around the inflectional mean velocity profile which develops between two coflowing streams of different velocities, differs in several ways from turbulence in a surface layer. Through these differences, the mixing-layer analogy provides an explanation for many of the observed distinctive features of canopy turbulence. These include: (a) ratios between components of the Reynolds stress tensor; (b) the ratio K K of the eddy diffusivities for heat and momentum; (c) the relative roles of ejections and sweeps; (d) the behaviour of the turbulent energy balance, particularly the major role of turbulent transport; and (e) the behaviour of the turbulent length scales of the active coherent motions (the dominant eddies responsible for vertical transfer near the top of the canopy).It is predicted that these length scales are controlled by the shear length scale L = U(h) U'(h) (where h is canopy height, U (z) is mean velocity as a function of height z, and U' = dU dz). In particular, the streamwise spacing of the dominant canopy eddies is = mLs, with m = 8.1. These predictions are tested against many sets of field and wind-tunnel data. We propose a picture of canopy turbulence in which eddies associated with inflectional instabilities are modulated by larger-scale, inactive turbulence, which is quasi-horizontal on the scale of the canopy.
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.78 No.3-4. Coherent eddies and turbulence in vegetation canopies : the mixing layer analogy [articles et extraits] / M.R. Raupach, Auteur ; Y. Brunet, Auteur ; J. J. Finnigan, Auteur . - 1996 . - p.351-382.
ISSN : 0006-8314
Langues : Français (fre)
Résumé : This paper argues that the active turbulence and coherent motions near the top of a vegetation canopy are patterned on a plane mixing layer, because of instabilities associated with the characteristic strong inflection in the mean velocity profile. Mixing-layer turbulence, formed around the inflectional mean velocity profile which develops between two coflowing streams of different velocities, differs in several ways from turbulence in a surface layer. Through these differences, the mixing-layer analogy provides an explanation for many of the observed distinctive features of canopy turbulence. These include: (a) ratios between components of the Reynolds stress tensor; (b) the ratio K K of the eddy diffusivities for heat and momentum; (c) the relative roles of ejections and sweeps; (d) the behaviour of the turbulent energy balance, particularly the major role of turbulent transport; and (e) the behaviour of the turbulent length scales of the active coherent motions (the dominant eddies responsible for vertical transfer near the top of the canopy).It is predicted that these length scales are controlled by the shear length scale L = U(h) U'(h) (where h is canopy height, U (z) is mean velocity as a function of height z, and U' = dU dz). In particular, the streamwise spacing of the dominant canopy eddies is = mLs, with m = 8.1. These predictions are tested against many sets of field and wind-tunnel data. We propose a picture of canopy turbulence in which eddies associated with inflectional instabilities are modulated by larger-scale, inactive turbulence, which is quasi-horizontal on the scale of the canopy.
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Code-barres Cote Support Localisation Section Disponibilité ART-6793-0 ART Document imprimé Bureau chercheur Bureau de ANSELMET, Fabien Disponible Boundary-Layer Meteorology, Vol.22 No.1. Averaging procedures for flow within vegetation canopies / M.R. Raupach
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.22 No.1 Titre : Averaging procedures for flow within vegetation canopies Type de document : articles et extraits Auteurs : M.R. Raupach, Auteur ; Roger H. Shaw, Auteur Année de publication : 1982 Importance : p.79-90 ISBN/ISSN/EAN : 0006-8314 Langues : Français (fre) Résumé : Two averaging schemes are considered: pure horizontal averaging at a single instant, and time averaging followed by horizontal averaging. These schemes produce different forms for the mean and turbulent kinetic energy balances, and especially for the `wake production' term describing the transfer of energy from large-scale motion to wake turbulence by form drag. The differences are primarily due to the appearance, in the covariances produced by the second scheme, of dispersive components arising from the spatial correlation of time-averaged flow variables. The two schemes are shown to coincide if these dispersive fluxes vanish.
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.22 No.1. Averaging procedures for flow within vegetation canopies [articles et extraits] / M.R. Raupach, Auteur ; Roger H. Shaw, Auteur . - 1982 . - p.79-90.
ISSN : 0006-8314
Langues : Français (fre)
Résumé : Two averaging schemes are considered: pure horizontal averaging at a single instant, and time averaging followed by horizontal averaging. These schemes produce different forms for the mean and turbulent kinetic energy balances, and especially for the `wake production' term describing the transfer of energy from large-scale motion to wake turbulence by form drag. The differences are primarily due to the appearance, in the covariances produced by the second scheme, of dispersive components arising from the spatial correlation of time-averaged flow variables. The two schemes are shown to coincide if these dispersive fluxes vanish.
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Code-barres Cote Support Localisation Section Disponibilité ART-7297-0 ART Document imprimé Bureau chercheur Bureau de PIETRI Laurence Disponible Boundary-Layer Meteorology, Vol.5. Measurements of internal waves and turbulence in two-dimensional stratified shear flows / Y. H. Pao
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.5 Titre : Measurements of internal waves and turbulence in two-dimensional stratified shear flows Type de document : articles et extraits Auteurs : Y. H. Pao, Auteur Année de publication : 1973 Importance : p.177-193 Langues : Français (fre)
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.5. Measurements of internal waves and turbulence in two-dimensional stratified shear flows [articles et extraits] / Y. H. Pao, Auteur . - 1973 . - p.177-193.
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Code-barres Cote Support Localisation Section Disponibilité ART-7663-0 ART Document imprimé Bureau chercheur Bureau de MEUNIER Patrice Disponible Boundary-Layer Meteorology, Vol.66 No.1-2. Detection of turbulent coherent motions in a forest canopy. 2, Time-scales and conditional averages / S. Collineau
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.66 No.1-2 Titre : Detection of turbulent coherent motions in a forest canopy. 2, Time-scales and conditional averages Type de document : articles et extraits Auteurs : S. Collineau, Auteur ; Y. Brunet, Auteur Année de publication : 1993 Importance : p.49-73 Langues : Français (fre) Résumé : Turbulent exchanges between plant canopies and the atmosphere are known to be strongly affected by intermittent coherent motions, which appear on time traces of turbulent variables as periodic, large-amplitude excursions from the mean. Detecting these features requires objective and powerful signal analysis techniques. We investigate here the possibilities offered by the recently developed wavelet transform, presented in a companion paper. For this purpose, a set of data acquired in a 13.5 m high pine forest in southwestern France was used, which provided time series of wind velocities and air temperature recorded at two levels simultaneously, under moderately unstable conditions. Firstly, a duration scale of the active part of coherent motions was estimated from the wavelet variance
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.66 No.1-2. Detection of turbulent coherent motions in a forest canopy. 2, Time-scales and conditional averages [articles et extraits] / S. Collineau, Auteur ; Y. Brunet, Auteur . - 1993 . - p.49-73.
Langues : Français (fre)
Résumé : Turbulent exchanges between plant canopies and the atmosphere are known to be strongly affected by intermittent coherent motions, which appear on time traces of turbulent variables as periodic, large-amplitude excursions from the mean. Detecting these features requires objective and powerful signal analysis techniques. We investigate here the possibilities offered by the recently developed wavelet transform, presented in a companion paper. For this purpose, a set of data acquired in a 13.5 m high pine forest in southwestern France was used, which provided time series of wind velocities and air temperature recorded at two levels simultaneously, under moderately unstable conditions. Firstly, a duration scale of the active part of coherent motions was estimated from the wavelet variance
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Code-barres Cote Support Localisation Section Disponibilité ART-7694-0 ART Document imprimé Bureau chercheur Bureau de PIETRI Laurence Disponible Boundary-Layer Meteorology, Vol.65 No.4. Detection of turbulent coherent motions in a forest canopy. 1, Wavelet analysis / S. Collineau
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.65 No.4 Titre : Detection of turbulent coherent motions in a forest canopy. 1, Wavelet analysis Type de document : articles et extraits Auteurs : S. Collineau, Auteur ; Y. Brunet, Auteur Année de publication : 1993 Importance : p.357-379 Langues : Français (fre) Résumé : Turbulence measurements performed at high frequencies yield data revealing intermittent and multi-scale processes. Analysing time series of turbulent variables thus requires extensive numerical treatment capable, for instance, of performing pattern recognition. This is particularly important in the case of the atmospheric surface layer and specifically in the vicinity of plant canopies, where large-scale coherent motions play a major role in the dynamics of turbulent transport processes. In this paper, we examine the ability of the recently developed wavelet transform to extract information on turbulence structure from time series of wind velocities and scalars
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.65 No.4. Detection of turbulent coherent motions in a forest canopy. 1, Wavelet analysis [articles et extraits] / S. Collineau, Auteur ; Y. Brunet, Auteur . - 1993 . - p.357-379.
Langues : Français (fre)
Résumé : Turbulence measurements performed at high frequencies yield data revealing intermittent and multi-scale processes. Analysing time series of turbulent variables thus requires extensive numerical treatment capable, for instance, of performing pattern recognition. This is particularly important in the case of the atmospheric surface layer and specifically in the vicinity of plant canopies, where large-scale coherent motions play a major role in the dynamics of turbulent transport processes. In this paper, we examine the ability of the recently developed wavelet transform to extract information on turbulence structure from time series of wind velocities and scalars
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Code-barres Cote Support Localisation Section Disponibilité ART-7695-0 ART Document imprimé Bureau chercheur Bureau de PIETRI Laurence Disponible Boundary-Layer Meteorology, Vol.52 No.3. Drag coefficients and turbulence spectra within three boreal forest canopies / B. D. Amiro
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.52 No.3 Titre : Drag coefficients and turbulence spectra within three boreal forest canopies Type de document : articles et extraits Auteurs : B. D. Amiro, Auteur Année de publication : 1990 Importance : p.227-246 ISBN/ISSN/EAN : 0006-8314 Langues : Français (fre)
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.52 No.3. Drag coefficients and turbulence spectra within three boreal forest canopies [articles et extraits] / B. D. Amiro, Auteur . - 1990 . - p.227-246.
ISSN : 0006-8314
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Code-barres Cote Support Localisation Section Disponibilité ART-8096-0 ART Document imprimé Bureau chercheur Bureau de PETROFF Alexandre Disponible Boundary-Layer Meteorology, Vol.51 No.1-2. Comparison of turbulence statistics within three boreal forest canopies / B. D. Amiro
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.51 No.1-2 Titre : Comparison of turbulence statistics within three boreal forest canopies Type de document : articles et extraits Auteurs : B. D. Amiro, Auteur Année de publication : 1990 Importance : p.99-121 ISBN/ISSN/EAN : 0006-8314 Langues : Français (fre)
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.51 No.1-2. Comparison of turbulence statistics within three boreal forest canopies [articles et extraits] / B. D. Amiro, Auteur . - 1990 . - p.99-121.
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Code-barres Cote Support Localisation Section Disponibilité ART-8097-0 ART Document imprimé Bureau chercheur Bureau de PETROFF Alexandre Disponible Boundary-Layer Meteorology, Vol.83 No.3. An analytical one-dimensional model of momentum transfer by vegetation with arbitrary structure / W. J. Massman
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.83 No.3 Titre : An analytical one-dimensional model of momentum transfer by vegetation with arbitrary structure Type de document : articles et extraits Auteurs : W. J. Massman, Auteur Année de publication : 1997 Importance : p.407-421 Langues : Français (fre) Résumé : An analytical one-dimensional model of momentum transfer by vegetation with variable foliage distribution, sheltering and drag coefficient is developed. The model relies on a simple parameterization of the ratio of the above-canopy friction velocity, u*, to the wind speed at the top of the canopy, u(h), to predict vegetation roughness length (z0) and displacement height (d) as functions of canopy height (h) and drag area index. Model predictions of d/h and z/h compare very favorably with observed values. A model sensitivity analysis suggests that sheltering effects for momentum transfer tend to make canopies with non-uniform foliage distribution resemble canopies with more uniform foliage distribution and that any influence wind speed has on d/h and z0/h is more likely to be related to the influence that wind speed may have on u*/u(h) rather than the influence wind speed may have on the foliage drag coefficient. Model results indicate that z0/h and d/h are sensitive to uncertainties in the numerical values of the model parameters, foliage density and distribution, sheltering effects and variations in drag coefficient within the canopy. In addition z0/h is also shown to be sensitive to the presence or absence of the roughness sublayer. Given the simplicity of the model it is suggested that it may be of use for land surface parameterizations in large scale models.
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.83 No.3. An analytical one-dimensional model of momentum transfer by vegetation with arbitrary structure [articles et extraits] / W. J. Massman, Auteur . - 1997 . - p.407-421.
Langues : Français (fre)
Résumé : An analytical one-dimensional model of momentum transfer by vegetation with variable foliage distribution, sheltering and drag coefficient is developed. The model relies on a simple parameterization of the ratio of the above-canopy friction velocity, u*, to the wind speed at the top of the canopy, u(h), to predict vegetation roughness length (z0) and displacement height (d) as functions of canopy height (h) and drag area index. Model predictions of d/h and z/h compare very favorably with observed values. A model sensitivity analysis suggests that sheltering effects for momentum transfer tend to make canopies with non-uniform foliage distribution resemble canopies with more uniform foliage distribution and that any influence wind speed has on d/h and z0/h is more likely to be related to the influence that wind speed may have on u*/u(h) rather than the influence wind speed may have on the foliage drag coefficient. Model results indicate that z0/h and d/h are sensitive to uncertainties in the numerical values of the model parameters, foliage density and distribution, sheltering effects and variations in drag coefficient within the canopy. In addition z0/h is also shown to be sensitive to the presence or absence of the roughness sublayer. Given the simplicity of the model it is suggested that it may be of use for land surface parameterizations in large scale models.
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Code-barres Cote Support Localisation Section Disponibilité ART-8388-0 ART Document imprimé Bureau chercheur Bureau de PIETRI Laurence Disponible Boundary-Layer Meteorology, Vol.71 No.1-2. Simplified expressions for vegetation roughness length and zero-plane displacement as functions of canopy height and area index / M.R. Raupach
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.71 No.1-2 Titre : Simplified expressions for vegetation roughness length and zero-plane displacement as functions of canopy height and area index Type de document : articles et extraits Auteurs : M.R. Raupach, Auteur Année de publication : 1994 Importance : p.211-216 Langues : Français (fre)
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.71 No.1-2. Simplified expressions for vegetation roughness length and zero-plane displacement as functions of canopy height and area index [articles et extraits] / M.R. Raupach, Auteur . - 1994 . - p.211-216.
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Code-barres Cote Support Localisation Section Disponibilité ART-8852-0 ART Document imprimé Bureau chercheur Bureau de PIETRI Laurence Disponible Boundary-Layer Meteorology, Vol.50 No.1-4. The internal boundary layer : a review / J. R. Garratt
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.50 No.1-4 Titre : The internal boundary layer : a review Type de document : articles et extraits Auteurs : J. R. Garratt, Auteur Année de publication : 1990 Importance : p.171-203 Langues : Français (fre)
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.50 No.1-4. The internal boundary layer : a review [articles et extraits] / J. R. Garratt, Auteur . - 1990 . - p.171-203.
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Code-barres Cote Support Localisation Section Disponibilité ART-9316-0 ART Document imprimé Bureau chercheur Bureau de PIETRI Laurence Disponible Boundary-Layer Meteorology, Vol.63 No.1-2. The effect of orchard crop structure on the integral length-scale of turbulence / P. J. Walklate
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.63 No.1-2 Titre : The effect of orchard crop structure on the integral length-scale of turbulence Type de document : articles et extraits Auteurs : P. J. Walklate, Auteur Année de publication : 1993 Importance : p.1-22 Langues : Français (fre)
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.63 No.1-2. The effect of orchard crop structure on the integral length-scale of turbulence [articles et extraits] / P. J. Walklate, Auteur . - 1993 . - p.1-22.
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Code-barres Cote Support Localisation Section Disponibilité ART-9524-0 ART Document imprimé Bureau chercheur Bureau de PIETRI Laurence Disponible Boundary-Layer Meteorology, Vol.69 No.3. Wind flows and forces in a model spruce forest / G. R. Stacey
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.69 No.3 Titre : Wind flows and forces in a model spruce forest Type de document : articles et extraits Auteurs : G. R. Stacey, Auteur ; R. E. Belcher, Auteur ; Barry A. Gardiner, Auteur ; C. J. Wood, Auteur Année de publication : 1994 Importance : p.311-334 ISBN/ISSN/EAN : 0006-8314 Langues : Français (fre) Résumé : Wind tunnel tests have been conducted on a 1:75 scale model of a Sitka spruce forest in a correctly scaled turbulent boundary-layer flow. 12000 tree models were manufactured with mass, flexibility and aerodynamic drag characteristics chosen to give dynamical similarity with typical 15 m trees in a 30ms–1 gale. To measure the dynamic response of a sample tree, set within this model forest, a miniature, fast response strain-gauge balance was designed and built. Linked to a computer for on-line data sampling, this balance provided measurements of the fluctuating along-wind and acrosswind components of the overturning moment at ground level, leading to values of mean and extreme moments and the frequency spectrum of the sway motion. Associated measurements of local wind flow characteristics were made with hot-wire anemometers and a laser anemometer. The response of the tree has the characteristics of classical lightly damped vibration and there is evidence that resonant sway motion increases the extreme overturning moments significantly above the values produced by wind gust forces alone.
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.69 No.3. Wind flows and forces in a model spruce forest [articles et extraits] / G. R. Stacey, Auteur ; R. E. Belcher, Auteur ; Barry A. Gardiner, Auteur ; C. J. Wood, Auteur . - 1994 . - p.311-334.
ISSN : 0006-8314
Langues : Français (fre)
Résumé : Wind tunnel tests have been conducted on a 1:75 scale model of a Sitka spruce forest in a correctly scaled turbulent boundary-layer flow. 12000 tree models were manufactured with mass, flexibility and aerodynamic drag characteristics chosen to give dynamical similarity with typical 15 m trees in a 30ms–1 gale. To measure the dynamic response of a sample tree, set within this model forest, a miniature, fast response strain-gauge balance was designed and built. Linked to a computer for on-line data sampling, this balance provided measurements of the fluctuating along-wind and acrosswind components of the overturning moment at ground level, leading to values of mean and extreme moments and the frequency spectrum of the sway motion. Associated measurements of local wind flow characteristics were made with hot-wire anemometers and a laser anemometer. The response of the tree has the characteristics of classical lightly damped vibration and there is evidence that resonant sway motion increases the extreme overturning moments significantly above the values produced by wind gust forces alone.
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Code-barres Cote Support Localisation Section Disponibilité ART-9546-0 ART Document imprimé Bureau chercheur Bureau de PIETRI Laurence Disponible Boundary-Layer Meteorology, Vol.54, No.1-2. The roughness of wind waves / N. Maat
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.54, No.1-2 Titre : The roughness of wind waves Type de document : articles et extraits Auteurs : N. Maat, Auteur ; C. Kraan, Auteur ; W. A. Oost Année de publication : 1991 Importance : p. 89-103 Langues : Anglais (eng) Résumé : In this paper, a new dynamic roughness equation for airflow over wind waves is proposed, based on relationships of dimensionless parameters and the 1986 HEXMAX field data. The equation can be considered as a modification of the Charnock formula. The data are also compared with the parameterizations of Toba and Koga, and of Hsu, and the consequences of the new equation for aerodynamic drag are discussed. In the new equation, the drag coefficient is expressed as a function of both wind speed and wave age c p/u*. This testifies to the strong wave-age dependence of the drag, found in several experimental studies. It is also in good agreement with results of a theoretical model of the airflow-seawave interaction, proposed by Janssen (1989).
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.54, No.1-2. The roughness of wind waves [articles et extraits] / N. Maat, Auteur ; C. Kraan, Auteur ; W. A. Oost . - 1991 . - p. 89-103.
Langues : Anglais (eng)
Résumé : In this paper, a new dynamic roughness equation for airflow over wind waves is proposed, based on relationships of dimensionless parameters and the 1986 HEXMAX field data. The equation can be considered as a modification of the Charnock formula. The data are also compared with the parameterizations of Toba and Koga, and of Hsu, and the consequences of the new equation for aerodynamic drag are discussed. In the new equation, the drag coefficient is expressed as a function of both wind speed and wave age c p/u*. This testifies to the strong wave-age dependence of the drag, found in several experimental studies. It is also in good agreement with results of a theoretical model of the airflow-seawave interaction, proposed by Janssen (1989). Réservation
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Code-barres Cote Support Localisation Section Disponibilité ART-199189 MAA Document imprimé Bureau chercheur Bureau de CAULLIEZ Guillemette Disponible Boundary-Layer Meteorology, Vol.39. Calculation of velocity skewness in real and artificial plant canopies / Roger H. Shaw
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.39 Titre : Calculation of velocity skewness in real and artificial plant canopies Type de document : articles et extraits Auteurs : Roger H. Shaw, Auteur ; Ido Seginer, Auteur Année de publication : 1987 Importance : p. 315-332 Langues : Anglais (eng)
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.39. Calculation of velocity skewness in real and artificial plant canopies [articles et extraits] / Roger H. Shaw, Auteur ; Ido Seginer, Auteur . - 1987 . - p. 315-332.
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Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire Boundary-Layer Meteorology, Vol.24, No.4. Statistics of atmospheric turbulence within and above a corn canopy / J. D. Wilson
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.24, No.4 Titre : Statistics of atmospheric turbulence within and above a corn canopy Type de document : articles et extraits Auteurs : J. D. Wilson, Auteur ; D. P. Ward, Auteur ; G. W. Thurtell, Auteur ; G. E. Kidd, Auteur Année de publication : 1982 Importance : p. 495-519 Langues : Anglais (eng) Résumé : Two three-dimensional split-film anemometers were used to measure turbulence statistics within and above a corn canopy. Normalised profiles of mean windspeed, root-mean-square velocity, momentum flux, and heat flux were constructed from half-hourly averages by dividing within-canopy measurements by the simultaneous canopy-top measurement. With the exception of the heat flux, these profiles showed consistent shape from day to day. Time series of the three velocity components were recorded on magnetic tape and subsequently analysed to obtain Eulerian time and length scales and the power spectrum of each component at several heights. The timescale was found to have a local minimum value at the top of the canopy. However the length scale L wformed from the timescale and the root-mean-square vertical velocity varied with height as L wsime 0.1 z. The power-spectra were non-dimensionalised to facilitate comparison of spectra at different heights and times. All spectra had -5/3 regions spanning at least two decades in frequency.
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.24, No.4. Statistics of atmospheric turbulence within and above a corn canopy [articles et extraits] / J. D. Wilson, Auteur ; D. P. Ward, Auteur ; G. W. Thurtell, Auteur ; G. E. Kidd, Auteur . - 1982 . - p. 495-519.
Langues : Anglais (eng)
Résumé : Two three-dimensional split-film anemometers were used to measure turbulence statistics within and above a corn canopy. Normalised profiles of mean windspeed, root-mean-square velocity, momentum flux, and heat flux were constructed from half-hourly averages by dividing within-canopy measurements by the simultaneous canopy-top measurement. With the exception of the heat flux, these profiles showed consistent shape from day to day. Time series of the three velocity components were recorded on magnetic tape and subsequently analysed to obtain Eulerian time and length scales and the power spectrum of each component at several heights. The timescale was found to have a local minimum value at the top of the canopy. However the length scale L wformed from the timescale and the root-mean-square vertical velocity varied with height as L wsime 0.1 z. The power-spectra were non-dimensionalised to facilitate comparison of spectra at different heights and times. All spectra had -5/3 regions spanning at least two decades in frequency. Réservation
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Code-barres Cote Support Localisation Section Disponibilité ART-1982495 WIL Document imprimé Bureau chercheur Bureau de Laurence Pietri Disponible Boundary-Layer Meteorology, Vol.44. Statistics of atmospheric turbulence within a natural black spruce forest canopy / B. D. Amiro
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.44 Titre : Statistics of atmospheric turbulence within a natural black spruce forest canopy Type de document : articles et extraits Auteurs : B. D. Amiro, Auteur ; P. A. Davis, Auteur Année de publication : 1988 Importance : p. 267-283 Langues : Anglais (eng)
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.44. Statistics of atmospheric turbulence within a natural black spruce forest canopy [articles et extraits] / B. D. Amiro, Auteur ; P. A. Davis, Auteur . - 1988 . - p. 267-283.
Langues : Anglais (eng)Exemplaires
Code-barres Cote Support Localisation Section Disponibilité aucun exemplaire Boundary-Layer Meteorology, Vol. 14. Modelling waving crops in a wind tunnel / J. J. Finnigan
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol. 14 Titre : Modelling waving crops in a wind tunnel Type de document : articles et extraits Auteurs : J. J. Finnigan, Auteur ; P. J. Mulhearn, Auteur Année de publication : 1978 Importance : p. 253-277 Langues : Anglais (eng)
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol. 14. Modelling waving crops in a wind tunnel [articles et extraits] / J. J. Finnigan, Auteur ; P. J. Mulhearn, Auteur . - 1978 . - p. 253-277.
Langues : Anglais (eng)Réservation
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Code-barres Cote Support Localisation Section Disponibilité ART-1978253 FIN Document imprimé Bureau chercheur Bureau de Laurence Pietri Disponible Boundary-Layer Meteorology, Vol. 2, No.4. Intensity of turbulence within canopies with simple and complex roughness elements / Ronald M. Cionco
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol. 2, No.4 Titre : Intensity of turbulence within canopies with simple and complex roughness elements Type de document : articles et extraits Auteurs : Ronald M. Cionco, Auteur Année de publication : 1972 Importance : p.453-465 Langues : Anglais (eng) Résumé : From a large group of both simple and complex canopies, the following properties have been identified. (1) For simple canopies (rice paddy, wheat field, larch tree plantation, and wind-tunnel wooden pegs), the intensity of turbulence was constant with height and decreased slowly above the vegetation. (2) For forests, wind-tunnel model trees and immature corn plants, the intensity of turbulence had a maximum in the main crown layer, a minimum in the trunk space and decreased gradually above the vegetation. (3) Seasonal variations of the turbulence intensities occurred in deciduous vegetation where the turbulence levels increased from the bare branch case to the leafy crown case. (4) In regard to thermal stability, the intensity of turbulence increased as the stability ratio decreased in a forest canopy. (5) Passage of larger-scale eddies and disturbances over or through the roughness elements produced high intensity levels both immediately above and below the canopy-air interface. (6) The intensity of turbulence increased as the density and structural complexity of the vegetation increased.
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol. 2, No.4. Intensity of turbulence within canopies with simple and complex roughness elements [articles et extraits] / Ronald M. Cionco, Auteur . - 1972 . - p.453-465.
Langues : Anglais (eng)
Résumé : From a large group of both simple and complex canopies, the following properties have been identified. (1) For simple canopies (rice paddy, wheat field, larch tree plantation, and wind-tunnel wooden pegs), the intensity of turbulence was constant with height and decreased slowly above the vegetation. (2) For forests, wind-tunnel model trees and immature corn plants, the intensity of turbulence had a maximum in the main crown layer, a minimum in the trunk space and decreased gradually above the vegetation. (3) Seasonal variations of the turbulence intensities occurred in deciduous vegetation where the turbulence levels increased from the bare branch case to the leafy crown case. (4) In regard to thermal stability, the intensity of turbulence increased as the stability ratio decreased in a forest canopy. (5) Passage of larger-scale eddies and disturbances over or through the roughness elements produced high intensity levels both immediately above and below the canopy-air interface. (6) The intensity of turbulence increased as the density and structural complexity of the vegetation increased. Réservation
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Code-barres Cote Support Localisation Section Disponibilité ART-1972453 CIO Document imprimé Bureau chercheur Bureau de Laurence Pietri Disponible Boundary-Layer Meteorology, Vol.40, No.4. A numerical study of the air flow within and around a single tree / G. Gross
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.40, No.4 Titre : A numerical study of the air flow within and around a single tree Type de document : articles et extraits Auteurs : G. Gross, Auteur Année de publication : 1987 Importance : p. 311-327 Langues : Anglais (eng) Résumé : A three-dimensional non-hydrostatic numerical model has been used to investigate the air flow and turbulence around a single tree.
The results for velocity and turbulence distributions have been compared with available data from windtunnel experiments; the agreement is satisfactory.
Simulations have been carried out for different meteorological conditions (wind speed, thermal stratification) as well as for different canopy characteristics (stem height, crown diameter, crown height, porosity).
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.40, No.4. A numerical study of the air flow within and around a single tree [articles et extraits] / G. Gross, Auteur . - 1987 . - p. 311-327.
Langues : Anglais (eng)
Résumé : A three-dimensional non-hydrostatic numerical model has been used to investigate the air flow and turbulence around a single tree.
The results for velocity and turbulence distributions have been compared with available data from windtunnel experiments; the agreement is satisfactory.
Simulations have been carried out for different meteorological conditions (wind speed, thermal stratification) as well as for different canopy characteristics (stem height, crown diameter, crown height, porosity).Réservation
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Code-barres Cote Support Localisation Section Disponibilité ART-1987311 GRO Document imprimé Bureau chercheur Bureau de Laurence Pietri Disponible Boundary-Layer Meteorology, Vol.15, No.1. Analysis of canopy index values for various canopy densities / Ronald M. Cionco
in Boundary layer meteorology
Titre de série : Boundary-Layer Meteorology, Vol.15, No.1 Titre : Analysis of canopy index values for various canopy densities Type de document : articles et extraits Auteurs : Ronald M. Cionco, Auteur Année de publication : 1978 Importance : p. 81-93 Langues : Anglais (eng) Résumé : Windspeed profile data of two quite different canopy density experiments-field and wind tunnel-have been analyzed based on least-square fittings. The results indicate that the two sets of index values of canopy flow behave in a similar manner with maxima occurring for optimum densities of one-third the potential full array of roughness elements. These index values also differ by some 0.2, but are still compatible when one accounts for the respective levels of turbulence within these dissimilar canopies
in Boundary layer meteorology
Boundary-Layer Meteorology, Vol.15, No.1. Analysis of canopy index values for various canopy densities [articles et extraits] / Ronald M. Cionco, Auteur . - 1978 . - p. 81-93.
Langues : Anglais (eng)
Résumé : Windspeed profile data of two quite different canopy density experiments-field and wind tunnel-have been analyzed based on least-square fittings. The results indicate that the two sets of index values of canopy flow behave in a similar manner with maxima occurring for optimum densities of one-third the potential full array of roughness elements. These index values also differ by some 0.2, but are still compatible when one accounts for the respective levels of turbulence within these dissimilar canopies Réservation
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Code-barres Cote Support Localisation Section Disponibilité ART-197881 CIO Document imprimé Bureau chercheur Bureau de Laurence Pietri Disponible