A Global Nonhydrostatic Semi-Lagrangian Atmospheric Model with Orography

Qian, Jian‐Hua; Semazzi, Fredrick H. M.; Scroggs, Jeffrey S.

doi:10.1175/1520-0493(1998)126<0747:agnsla>2.0.co;2

Cited by 43 publications

(33 citation statements)

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“…However, for gravity waves the domain size on the sphere has typically restricted the test cases to linear and nonlinear hydrostatic waves in a uniform flow, e.g. Qian et al (1998), Tomita and Satoh (2004). Notwithstanding the usefulness of such tests, the framework proposed in this article opens up the possibility to compare global non-hydrostatic models quantitatively and qualitatively with large-eddy simulation (LES) benchmarks of limitedarea models and Cartesian-domain analytic solutions published in the literature.…”

Section: Introductionmentioning

confidence: 99%

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: Introductionmentioning

confidence: 99%

A framework for testing global non‐hydrostatic models

Wedi

Smolarkiewicz

2009

Quart J Royal Meteoro Soc

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“…IFS, UM, GSM, GFS. SISL-based schemes guarantee boundedness of the solution and unconditional stability [96], which have the advantagecompared to explicit schemes-that they permit a relatively large time-step and a very competitive time-to-solution performance [24,73,105,111,114].…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

Current and Emerging Time-Integration Strategies in Global Numerical Weather and Climate Prediction

Mengaldo

Wyszogrodzki

Diamantakis

et al. 2018

Arch Computat Methods Eng

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The continuous partial differential equations governing a given physical phenomenon, such as the Navier-Stokes equations describing the fluid motion, must be numerically discretized in space and time in order to obtain a solution otherwise not readily available in closed (i.e., analytic) form. While the overall numerical discretization plays an essential role in the algorithmic efficiency and physically-faithful representation of the solution, the time-integration strategy commonly is one of the main drivers in terms of cost-to-solution (e.g., time-or energy-to-solution), accuracy and numerical stability, thus constituting one of the key building blocks of the computational model. This is especially true in time-critical applications, including numerical weather prediction (NWP), climate simulations and engineering. This review provides a comprehensive overview of the existing and emerging time-integration (also referred to as time-stepping) practices used in the operational global NWP and climate industry, where global refers to weather and climate simulations performed on the entire globe. While there are many flavors of time-integration strategies, in this review we focus on the most widely adopted in NWP and climate centers and we emphasize the reasons why such numerical solutions were adopted. This allows us to make some considerations on future trends in the field such as the need to balance accuracy in time with substantially enhanced time-to-solution and associated implications on energy consumption and running costs. In addition, the potential for the co-design of time-stepping algorithms and underlying high performance computing hardware, a keystone to accelerate the computational performance of future NWP and climate services, is also discussed in the context of the demanding operational requirements of the weather and climate industry.

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“…The retention of all mean and perturbation terms and the description involving the semi-Lagrangian method makes the presentation of the technique complicated. The description of the semi-implicit, semi-Lagrangian (SISL) algorithm employed by Qian et al (1998) is also very complicated and we conjecture that the semi-implicit solution of the fully compressible equations has not been taken up so widely because these descriptions are so complex.…”

Section: Introductionmentioning

confidence: 99%

Curl-Free Pressure Gradients over Orography in a Solution of the Fully Compressible Euler Equations with Implicit Treatment of Acoustic and Gravity Waves

Weller

Shahrokhi

2014

Monthly Weather Review

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Steep orography can cause noisy solutions and instability in models of the atmosphere. A new technique for modeling flow over orography is introduced that guarantees curl-free gradients on arbitrary grids, implying that the pressure gradient term is not a spurious source of vorticity. This mimetic property leads to better hydrostatic balance and better energy conservation on test cases using terrain-following grids. Curl-free gradients are achieved by using the covariant components of velocity over orography rather than the usual horizontal and vertical components.In addition, gravity and acoustic waves are treated implicitly without the need for mean and perturbation variables or a hydrostatic reference profile. This enables a straightforward description of the implicit treatment of gravity waves.Results are presented of a resting atmosphere over orography and the curl-free pressure gradient formulation is advantageous. Results of gravity waves over orography are insensitive to the placement of terrain-following layers. The model with implicit gravity waves is stable in strongly stratified conditions, with NDt up to at least 10 (where N is the Brunt-Väisälä frequency). A warm bubble rising over orography is simulated and the curl-free pressure gradient formulation gives much more accurate results for this test case than a model without this mimetic property.

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A Global Nonhydrostatic Semi-Lagrangian Atmospheric Model with Orography

Cited by 43 publications

References 0 publications

A framework for testing global non‐hydrostatic models

A framework for testing global non‐hydrostatic models

Current and Emerging Time-Integration Strategies in Global Numerical Weather and Climate Prediction

Curl-Free Pressure Gradients over Orography in a Solution of the Fully Compressible Euler Equations with Implicit Treatment of Acoustic and Gravity Waves

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