Characterization of Wind Meandering in Low-Wind-Speed Conditions

Mortarini, Luca; Stefanello, Michel; Degrazia, Gervásio Annes; Roberti, Débora Regina; Castelli, Silvia; Anfossi, D.

doi:10.1007/s10546-016-0165-6

Cited by 54 publications

(66 citation statements)

References 40 publications

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“…The ratio between

q

and

p

represents the looping parameter

m

m = \frac{q}{p} .

Values of

m < 1

indicate that the turbulent exponential decay prevails on the oscillating part of the EAF, whereas values of

m > 1

indicate boundary‐layer dynamics in which non‐turbulent wave‐like motions play an important role. Mortarini et al ., (, ) classified as “meandering” episodes those hours when

m_{u}

m_{v}

and

m_{T}

are simultaneously larger than 1, and as “non‐meandering” episodes those hours when the theoretical formulation (Equation ) is not able to fit the observed EAF. (Cava et al ., give a detailed description of the fitting method.)…”

Section: Identification Of Meandering and Gravity Wavesmentioning

confidence: 99%

“…Since meandering motions are generally related to large variations of the wind direction, they may significantly influence the scalar horizontal dispersion, in particular in low wind speed and in very stable conditions or, in general, in the presence of weak vertical turbulent mixing (Anfossi et al ., ; Mahrt and Mills, ; Mortarini et al ., ). Though meandering modes are more common in stable atmospheric stratification at night‐time, they have also been observed during daytime in calm conditions (Anfossi et al ., ; Oettl et al ., ; Vickers et al ., ; Mortarini et al ., ). Nonetheless, the physical causes responsible for horizontal meandering are not yet well understood in both stable and unstable atmospheric stratifications.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of submeso motions on scalar oscillations and surface energy balance

Stefanello

Cava

Giostra

et al. 2020

Quart J Royal Meteoro Soc

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The presence of wave‐like structures in the planetary boundary layer and their influence on the scalar fluxes and on the surface energy balance were investigated analyzing one year of continuous measurements collected in southern Brazil. Submeso oscillating patterns in the wind velocity components, temperature and scalar (CO2, H2O) concentrations were isolated using their auto‐correlation functions. The analysis showed that low wind speeds are necessary to trigger wavy motions. During night‐time, in the presence of large vertical temperature gradients, horizontal meandering and internal gravity waves are dominant features of the stable boundary layer. Furthermore, a significant number of meandering cases were identified also during daytime in neutral conditions associated with low values of net radiation. One case‐study showed how, during daytime, the wave‐like patterns may be triggered by variations in the net radiation. Spectral analysis on the whole dataset showed that oscillations in the wind velocity and temperature field are frequently associated with CO2 and H2O wavy patterns with similar time‐scales. These non‐turbulent oscillations produce unpredictable large‐scale contributions to vertical fluxes of temperature and scalar concentrations. The energy budget analysis showed how the choice of a proper averaging time filters out these contributions and improves the energy budget closure, as well as the estimation of the net ecosystem exchange. The results confirm the influence of submeso motions in scalar dispersion, flux patterns and surface energy balance during low wind speed conditions and stable stratification.

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“…The ratio between

q

and

p

represents the looping parameter

m

m = \frac{q}{p} .

Values of

m < 1

indicate that the turbulent exponential decay prevails on the oscillating part of the EAF, whereas values of

m > 1

indicate boundary‐layer dynamics in which non‐turbulent wave‐like motions play an important role. Mortarini et al ., (, ) classified as “meandering” episodes those hours when

m_{u}

m_{v}

and

m_{T}

Section: Identification Of Meandering and Gravity Wavesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of submeso motions on scalar oscillations and surface energy balance

Stefanello

Cava

Giostra

et al. 2020

Quart J Royal Meteoro Soc

Self Cite

View full text Add to dashboard Cite

show abstract

“…These values are presented in Table 1. [4]. The characteristic values of the meandering phenomenon are exhibited in Table 1, which can be used in Eqs.…”

Section: Reproducing Observed Meandering Autocorrelation Functionsmentioning

confidence: 99%

“…This looping pattern with the presence of negative lobes in autocorrelation functions, which characterize the meandering observed phenomenon, can be well reproduced by particular mathematical formulations. With this good fit, it is possible to estimate the principal physical variables that specify the meandering flow [4,5].…”

Section: Introductionmentioning

confidence: 99%

Testing Physical and Mathematical Criteria in a New Meandering Autocorrelation Function

Szinvelski¹,

Buligon²,

BaptistellaStefanello³

et al. 2017

Turbulence Modelling Approaches - Current State, Development Prospects, Applications

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An alternative formulation for the low wind speed-meandering autocorrelation function is presented. Employing distinct theoretical criteria, this mathematical formulation, from a physical point of view, is validated. This expression for the meandering autocorrelation function reproduces well-observed wind-meandering data measured in a micrometeorological site located in a pampa ecosystem area (South Brazil). The comparison shows that the alternative relation for the meandering autocorrelation function is suitable to provide meandering characteristic parameters. Employing MacLaurin's series expansion of a lateral dispersion parameter that represents cases in which turbulence and oscillatory movements associated to the meandering events coexist, a new formulation for the turbulence/meandering dissipation rate has been presented.

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“…The meandering enhanced dispersion occurring in low wind conditions (U < 1.5 m/s) [1], characterized by low frequency horizontal wind oscillations, is a relevant mechanism to describe the diffusion of atmospheric contaminants [2]. Thus, the horizontal wind meandering phenomenon is an important physical component that must be incorporated in air pollution models.…”

Section: Introductionmentioning

confidence: 99%

Physical and Mechanical Characterization of Copaifera sp. Wood Specie

Aquino¹,

Silveira²,

Degrazia³

et al. 2018

ajee

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The aim of this work is evaluating the behaviour of the pollutant plume in the region where the INEL (USA) experiment was released. The INEL diffusion experiment consists of a test series that was accomplished in a flat and uniform terrain under stable low wind atmospheric conditions. Thusly, accounting for the current understanding of the stable planetary boundary layer (PBL) turbulence pattern and characteristics (stable eddy diffusivities), a modelling system consisting of the WRF (Weather Research and Forecasting) and LES-PALM (Large-Eddy Simulation-Parallelized) model is employed to describe the dispersive effects associated with the wind meandering movements. The potential temperature profiles and heat fluxes generated by the WRF model will be used as initial conditions to the LES-PALM model. PALM is referred as a model to Large Eddy Simulation (LES) to atmospheric and oceanic fluxes that is destined to parallel computer architectures. The horizontal wind meandering generated by LES-PALM model will be used as initial conditions to the dispersion model based in the 3D-GILTT (3D Generalized Integral Laplace Transform Technique) technique that analytically solves the advection-diffusion equation. This technique of the integral transform combines a series expansion with an integration. In the expansion a trigonometric base, determined from the Sturm-Liouville auxiliary problem, is employed. The integration is made in all range of the transformed variable, making use of the orthogonality property of the base used in the expansion. The resultant ordinary differential equations system is analytically solved using the Laplace transform and diagonalization. The simulation results, generated from this modelling system are show to agree with the observed ground-level centreline concentrations of INEL experiments and also with those of other atmospheric dispersion models. The present study shows that the horizontal wind field provided by the coupling of two meteorological models (WRF and LES-PALM) can be used in a Eulerian diffusion model to properly simulate meandering enhanced dispersion of contaminants in a low wind speed stable PBL.

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Characterization of Wind Meandering in Low-Wind-Speed Conditions

Cited by 54 publications

References 40 publications

Influence of submeso motions on scalar oscillations and surface energy balance

Influence of submeso motions on scalar oscillations and surface energy balance

Testing Physical and Mathematical Criteria in a New Meandering Autocorrelation Function

Physical and Mechanical Characterization of Copaifera sp. Wood Specie

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