Alternative Anisotropic Formulations for Eddy-Viscosity Models in the Weather Research and Forecasting Model

Simon, Jason; Chow, Fotini Katopodes

doi:10.1007/s10546-021-00642-0

Cited by 6 publications

(14 citation statements)

References 33 publications

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“…Also the fields of potential temperature and specific humidity become dominated by much larger structures as compared to what is found for smaller values of Δ x hor . These results corroborate the results of similar LES runs with anisotropic diffusion and a large value Δ x hor = 1.2 km presented by Simon and Chow (2021) (see their Figures 4f and 4g).…”

Section: Resultssupporting

confidence: 91%

“…As a potential remedy to the problems found for the anisotropic diffusion approach at Gray Zone resolutions its formulation might be modified. According to Simon and Chow (2021) such a step could perhaps be taken by applying an enhanced value for the vertical eddy diffusivity for a coarsening horizontal grid. Their parameterization is inspired by a diagnosis of the scale-dependent horizontal and vertical eddy diffusivities from three-dimensional LES fields by Kitamura (2015).…”

Section: Discussionmentioning

confidence: 99%

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Dependency of Mesoscale Organization on Grid Anisotropy in Large‐Eddy Simulations of Convective Boundary Layers at Gray Zone Resolutions

Roode

Siebesma

Jansson

et al. 2022

J Adv Model Earth Syst

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A new generation of operational atmospheric models operating at horizontal resolutions in the range 200 m ∼ 2 km is becoming increasingly popular for operational use in numerical weather prediction and climate applications. Such grid spacings are becoming sufficiently fine to resolve a fraction of the turbulent transports. Here we analyze Large‐eddy simulation results of a convective boundary layer obtained by coarsening horizontal grid spacings up to 800 m. The aim is to explore the dependency of the mean state and turbulent fluxes on the grid resolution. Both isotropic and anisotropic eddy diffusion approaches are evaluated, where in the latter case the horizontal and vertical eddy diffusivities differ in accord with their horizontal and vertical grid spacings. For coarsening horizontal grid sizes entrainment at the top of the boundary layer tends to get slightly enhanced for isotropic diffusion, whereas for the anisotropic diffusion approach the vertically well‐mixed boundary‐layer structure becomes severely degraded. An analysis of the energy spectrum shows that anisotropic diffusion causes relatively more dissipation of variance at smaller length scales. This leads, in turn, to a shift of spectral energy toward larger length scales that also becomes apparent from a rather different kind of spatial organization of convection. The present study therefore suggests that details with regards to the representation of processes at small scales might impact the organization at length scales much larger than the smallest scales that can be resolved by the model.

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Section: Resultssupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Dependency of Mesoscale Organization on Grid Anisotropy in Large‐Eddy Simulations of Convective Boundary Layers at Gray Zone Resolutions

Roode

Siebesma

Jansson

et al. 2022

J Adv Model Earth Syst

View full text Add to dashboard Cite

show abstract

“…Also the fields of potential temperature and specific humidity become dominated by much larger structures as compared to what is found for smaller values of Δx hor . These results corroborate the results of similar LES runs with anisotropic diffusion and a large value Δx hor = 1.2 km presented by Simon and Chow (2021) (see their Figures 4f and 4g).…”

Section: Figuresupporting

confidence: 91%

“…The current DALES code applies the isotropic diffusion approach following Deardorff (1980) and is identical to the scheme studied earlier by Van Zanten (2000). However, for the present study DALES has been elaborated with an anisotropic diffusion approach following the System for Atmospheric Modeling (SAM) LES model (Stevens, Vali, et al, 2005) and similar to the Weather Research and Forecasting (WRF) LES model (Simon & Chow, 2021).…”

Section: De Roode Et Almentioning

confidence: 99%

Dependency of mesoscale organization on grid anisotropy in large-eddy simulations of convective boundary layers at Gray Zone resolutions.

Roode

Siebesma

Jansson

et al. 2022

Preprint

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“…In the recent years, the emphasis in problems of simulation (and prediction) of the state of the atmospheric boundary layer with high spatial and time resolution is at consideration of the processes characterized by the meso-gamma scale (from hundreds of meters to several kilometers), which are included in the so-called gray zone in the international literature [1][2][3][4][5][6][7][8][9][10][11]. The experimental studies of processes with these scales usually involve both laboratory and field experiments [12][13][14][15][16].…”

mentioning

confidence: 99%

Comparison of the contributions of turbulent and mesoscale processes to the wind field of the atmospheric surface layer

Gladkikh

Mamysheva

Nevzorova

et al. 2022

28th International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics

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The mixed moments of the wind vector components are compared when these components are decomposed into deterministic, meso-gamma-scale, and turbulent parts. The results of wind measurements at heights of 5 and 10 m in August 2021 at a site with natural landscape (large grassy meadow) are used. It is shown that meso-gamma-scale variations of the wind field should necessarily be taken into account in problems of modeling (predicting) the state of the atmospheric surface layer.

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Alternative Anisotropic Formulations for Eddy-Viscosity Models in the Weather Research and Forecasting Model

Cited by 6 publications

References 33 publications

Dependency of Mesoscale Organization on Grid Anisotropy in Large‐Eddy Simulations of Convective Boundary Layers at Gray Zone Resolutions

Dependency of Mesoscale Organization on Grid Anisotropy in Large‐Eddy Simulations of Convective Boundary Layers at Gray Zone Resolutions

Dependency of mesoscale organization on grid anisotropy in large-eddy simulations of convective boundary layers at Gray Zone resolutions.

Comparison of the contributions of turbulent and mesoscale processes to the wind field of the atmospheric surface layer

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