Explicit global simulation of the mesoscale spectrum of atmospheric motions

Takahashi, Yoshiyuki O.; Hamilton, Kevin; Ohfuchi, Wataru

doi:10.1029/2006gl026429

Cited by 66 publications

(81 citation statements)

References 21 publications

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“…The energy spectrum drops down in the region of spectral tail. However, the behavior of the spectral tail depends on the numerical diffusion , although the k 3 and k 5/3 power laws are produced by the atmospheric dynamics (Takahashi et al 2006). Figure 3 shows the energy spectra in the zonal wavenumber domain for glevel-11 at the different 4 levels in the troposphere (1000, 850, 500, and 200 hPa).…”

Section: Resultsmentioning

confidence: 99%

Characteristics of the Kinetic Energy Spectrum of NICAM Model Atmosphere

Terasaki

Tanaka

Satoh

2009

SOLA

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In this study, characteristics of the energy spectrum in the zonal wavenumber domain are examined for the cloud resolving global model NICAM. A series of numerical experiments are conducted for NICAM with various horizontal resolutions from 224 km (glevel-5) to 7.0 km (glevel-10) using the T2K-Tsukuba System and 3.5 km (glevel-11) using the Earth Simulator (ES). The energy spectra of most of horizontal resolutions obey k 3 power law in synoptic and sub-synoptic scales (wavenumbers k = 5 to 30). However, the energy slope for glevel-5 becomes much steeper around zonal wavenumber k = 10. Nastrom et al. (1985) explained that the energy spectrum near the tropopause at wavelengths below 400 km appears to follow the k 5/3 power. This scale corresponds to about k = 70 near 45°N. It is found that the energy spectra for k > 30 for glevel-10 and 11 follow the k 5/3 power law. These results agree quite well with the observational studies. It is also found that the kinetic energy of the vertical wind is white noise spectrum.

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Section: Resultsmentioning

confidence: 99%

Characteristics of the Kinetic Energy Spectrum of NICAM Model Atmosphere

Terasaki

Tanaka

Satoh

2009

SOLA

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“…They pointed out that the CAM finite volume dynamical core with second-order divergence damping has a clearly weaker divergent component of the simulated flow, and expect the version with fourth-order damping to behave similarly to the spectral element core. Takahashi et al (2006) carried out a series of simulations with the spectral model AFES to empirically determine the appropriate relationship between the magnitude of hyper-diffusion and model resolution, aiming at correctly capturing the shape of the KE in both the inertial regime and the mesoscale regime. Their results suggest a scaling of n −3.22 0 (or x 3.22 , where n 0 is the truncation wavenumber, and x the grid spacing) for the diffusion coefficient.…”

Section: First Results From the Aqua-planet Experimentsmentioning

confidence: 99%

The ICON-1.2 hydrostatic atmospheric dynamical core on triangular grids – Part 1: Formulation and performance of the baseline version

et al. 2013

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Abstract. As part of a broader effort to develop nextgeneration models for numerical weather prediction and climate applications, a hydrostatic atmospheric dynamical core is developed as an intermediate step to evaluate a finitedifference discretization of the primitive equations on spherical icosahedral grids. Based on the need for mass-conserving discretizations for multi-resolution modelling as well as scalability and efficiency on massively parallel computing architectures, the dynamical core is built on triangular C-grids using relatively small discretization stencils. This paper presents the formulation and performance of the baseline version of the new dynamical core, focusing on properties of the numerical solutions in the setting of globally uniform resolution. Theoretical analysis reveals that the discrete divergence operator defined on a single triangular cell using the Gauss theorem is only first-order accurate, and introduces grid-scale noise to the discrete model. The noise can be suppressed by fourth-order hyper-diffusion of the horizontal wind field using a time-step and grid-size-dependent diffusion coefficient, at the expense of stronger damping than in the reference spectral model.A series of idealized tests of different complexity are performed. In the deterministic baroclinic wave test, solutions from the new dynamical core show the expected sensitivity to horizontal resolution, and converge to the reference solution at R2B6 (35 km grid spacing). In a dry climate test, the dynamical core correctly reproduces key features of the meridional heat and momentum transport by baroclinic eddies. In the aqua-planet simulations at 140 km resolution, the new model is able to reproduce the same equatorial wave propagation characteristics as in the reference spectral model, including the sensitivity of such characteristics to the meridional sea surface temperature profile.These results suggest that the triangular-C discretization provides a reasonable basis for further development. The main issues that need to be addressed are the grid-scale noise from the divergence operator which requires strong damping, and a phase error of the baroclinic wave at medium and low resolutions.

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“…For uniform resolutions with an average grid spacing of x, often ν = c 0 ( x) 3.2 , for some constant c 0 > 0. This scaling is obtained by experimentation and is found to be effective for several different dynamical cores over a wide range of resolutions (Boville, 1991;Takahashi et al, 2006; Dennis , 2012). We take a slightly more general form and allow ν = c 0 ( x) s for a scaling parameter s. The constantcoefficient hyperviscosity is used for quasi-uniform grids, where we follow the convention of defining x by the average number of degrees of freedom on the equator.…”

Section: Constant-coefficient Hyperviscositymentioning

confidence: 99%

The spectral element method (SEM) on variable-resolution grids: evaluating grid sensitivity and resolution-aware numerical viscosity

et al. 2014

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Abstract. We evaluate the performance of the Community Atmosphere Model's (CAM) spectral element method on variable-resolution grids using the shallow-water equations in spherical geometry. We configure the method as it is used in CAM, with dissipation of grid scale variance, implemented using hyperviscosity. Hyperviscosity is highly scale selective and grid independent, but does require a resolutiondependent coefficient. For the spectral element method with variable-resolution grids and highly distorted elements, we obtain the best results if we introduce a tensor-based hyperviscosity with tensor coefficients tied to the eigenvalues of the local element metric tensor. The tensor hyperviscosity is constructed so that, for regions of uniform resolution, it matches the traditional constant-coefficient hyperviscosity. With the tensor hyperviscosity, the large-scale solution is almost completely unaffected by the presence of grid refinement. This later point is important for climate applications in which long term climatological averages can be imprinted by stationary inhomogeneities in the truncation error. We also evaluate the robustness of the approach with respect to grid quality by considering unstructured conforming quadrilateral grids generated with a well-known grid-generating toolkit and grids generated by SQuadGen, a new open source alternative which produces lower valence nodes.

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Explicit global simulation of the mesoscale spectrum of atmospheric motions

Cited by 66 publications

References 21 publications

Characteristics of the Kinetic Energy Spectrum of NICAM Model Atmosphere

Characteristics of the Kinetic Energy Spectrum of NICAM Model Atmosphere

The ICON-1.2 hydrostatic atmospheric dynamical core on triangular grids – Part 1: Formulation and performance of the baseline version

The spectral element method (SEM) on variable-resolution grids: evaluating grid sensitivity and resolution-aware numerical viscosity

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