Implications of the Hydrostatic Assumption on Atmospheric Gravity Waves

Keller, Teddie L.

doi:10.1175/1520-0469(1994)051<1915:iothao>2.0.co;2

Cited by 58 publications

(63 citation statements)

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“…The upper limit of the IFS is formally always at p = 0, whereas a rigid lid upper boundary at 25 km was chosen in EULAG for computational efficiency. While in the non-hydrostatic IFS no absorbers are used, in EULAG the damping profile α = τ −1 max{0, (Z − Z thres )/(Z top − Z thres )} is applied with Z thres = 20 km and τ = 300 s. non-hydrostatic solutions may be compared with the solution obtained with the hydrostatic IFS (Figure 2), which is consistent with the analytic solution (maximum contours 0.6 m s −1 ) of the same case presented in Keller (1994). The hydrostatic model fails to represent the trapping and the horizontal propagation of lee waves.…”

Section: Quasi-two-dimensional Orographic Flow With Linear Vertical Ssupporting

confidence: 75%

“…This classical problem -studied in Wurtele et al (1987) and Keller (1994) -constitutes a particularly discriminating test, because in the presence of shear the non-hydrostatic and hydrostatic equations predict a fundamentally different propagation of orographically forced gravity waves. While hydrostatic models produce a vertically propagating mountain gravity wave, the correct solution is that of a trapped, horizontally propagating gravity wave.…”

Section: Quasi-two-dimensional Orographic Flow With Linear Vertical Smentioning

confidence: 99%

“…While hydrostatic models produce a vertically propagating mountain gravity wave, the correct solution is that of a trapped, horizontally propagating gravity wave. For a direct comparison with the published analytical results, the same parameter space as in Keller (1994) is explored but with a suitably modified mountain to accommodate the global spherical geometry of the models.…”

Section: Quasi-two-dimensional Orographic Flow With Linear Vertical Smentioning

confidence: 99%

“…For the hydrostatic IFS, the solution is characterized by an entirely vertical response to the mountain forcing; cf. Keller (1994). Here vertical absorbers are important to avoid reflection at the model top and to obtain the analytic solution for an unbounded atmosphere.…”

Section: Quasi-two-dimensional Orographic Flow With Linear Vertical Smentioning

confidence: 99%

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A framework for testing global non‐hydrostatic models

Wedi

Smolarkiewicz

2009

Quart J Royal Meteoro Soc

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ABSTRACT:With the emergence of non-hydrostatic global dynamical cores, an alternative testing strategy is proposed, where the planetary radius is suitably reduced to capture non-hydrostatic phenomena without incurring the computational cost of actual simulations of weather and climate at non-hydrostatic resolution. The procedure is simple and tests various aspects of the discretized hydrostatic and non-hydrostatic equations in the same setting on a sphere. Furthermore, it facilitates verification against Cartesian-domain analytic solutions and against large-eddy simulation (LES) benchmarks available for limited-area models. The proposed framework is illustrated with examples of inertia-gravity wave dynamics in linear and nonlinear regimes, including flows past idealized mountains, stratified shear flows and critical layers. Finally, an intercomparison of the Held-Suarez climate variability for reduced-size planets is presented, which provides a path for future investigations on the dynamics of convective boundary layers on a sphere. This assesses the ability to adequately capture interactions of large-scale dynamics with intermittent turbulent structures, an important aspect of future weather and climate predictions.

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Section: Quasi-two-dimensional Orographic Flow With Linear Vertical Ssupporting

confidence: 75%

Section: Quasi-two-dimensional Orographic Flow With Linear Vertical Smentioning

confidence: 99%

Section: Quasi-two-dimensional Orographic Flow With Linear Vertical Smentioning

confidence: 99%

Section: Quasi-two-dimensional Orographic Flow With Linear Vertical Smentioning

confidence: 99%

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A framework for testing global non‐hydrostatic models

Wedi

Smolarkiewicz

2009

Quart J Royal Meteoro Soc

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“…The model successfully passed a large variety of idealized test cases, such as vertical-plane 2D simulations of orographic flows, including trapped lee waves (Keller, 1994), bubble convection cases at decametric scales (Robert, 1993) and 3D flows with and without Earth rotation over idealized and real orography, at various scales. During these tests, the model constantly showed its ability to perform stable integrations with typical CFL numbers up to 10 at kilometric resolutions, thus indicating a reasonable appropriateness for further NWP use.…”

Section: Introductionmentioning

confidence: 99%

Dynamical kernel of the Aladin–NH spectral limited‐area model: Revised formulation and sensitivity experiments

Bénard

Vivoda

Mašek

et al. 2010

Quart J Royal Meteoro Soc

129

154

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† The contribution of C. Smith was written in the course of his employment at the Met Office, UK and is published with the permission of the controller of HMSO and the Queen's Printer for Scottland.Drawing from the results of theoretical studies about the behaviour of constantcoefficients semi-implicit schemes, the dynamical kernel of the Aladin-NH spectral limited-area numerical weather prediction (NWP) model has been modified in order to allow for a stable and efficient integration of the fully elastic Euler equations. The resulting dynamical kernel offers the possibility to use semi-Lagrangian transport schemes together with two-time-level discretizations at kilometric scales for NWP purposes. The main characteristics of the adiabatic part of the model formulation and the space and time discretization are described in this article. In order to illustrate the dependence of the results on adjustable parameters of the dynamical kernel, some real-case dynamical-adaptation forecasts performed with a basic physical parameterization package are presented. The results obtained with this model in real-case experiments fully confirm the conclusions drawn in previous numerical analysis studies. The good quality of the results is found to be compatible with a routine exploitation in a NWP framework. The Aladin-NH dynamical kernel has been used in the operational NWP 'AROME' model since December 2008 at the kilometric scale, with an appropriate physical parameterization package and data assimilation system.

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MPDATA and grid adaptivity in geophysical fluid flow models

Prusa

Gutowski

2005

Numerical Methods in Fluids

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SUMMARYGeophysical ows can profoundly a ect human activities. Often characterized by an astonishing range of signiÿcant scales and a rich assortment of physical processes, the complexity of such ows generally precludes all but numerical simulation for prediction and understanding-yet even state of the art computational models may be severely challenged by problems such as hurricane intensiÿcation. Although a number of signiÿcant issues are involved, a major factor is often grid resolution, for which grid adaptivity (GA) can be useful. Our experience has been that MPDATA is particularly well suited for GA. This paper sketches general details of a model that blends MPDATA with continuous GA; highlights a tensor viewpoint of the geometric conservation law; and presents results for both global and regional atmospheric applications. Together, the examples demonstrate the advantages of using GA with MPDATA to resolve ÿne-scale features-explicit gravity waves generated by ow over orography. Resolution of these waves (or lack thereof) are shown to a ect global climate; furthermore, wave resolution is shown to depend upon the regional atmospheric environment. Finally the regional simulations show a surprising increase in the complexity of the waveÿelds as resolution is increased to the point of resolving nonhydrostatic e ects.

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Implications of the Hydrostatic Assumption on Atmospheric Gravity Waves

Cited by 58 publications

References 0 publications

A framework for testing global non‐hydrostatic models

A framework for testing global non‐hydrostatic models

Dynamical kernel of the Aladin–NH spectral limited‐area model: Revised formulation and sensitivity experiments

MPDATA and grid adaptivity in geophysical fluid flow models

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