Held-Suarez simulations with the Community Atmosphere Model Spectral Element (CAM-SE) dynamical core: A global axial angular momentum analysis using Eulerian and floating Lagrangian vertical coordinates

Abstract In today’s atmospheric numerical modeling, scalable and highly accurate numerical schemes are of particular interest. To address these issues Galerkin schemes, such as the spectral element method, have received more attention in the last decade. They also provide other state-of-the-art capabilities such as improved conservation. However, the tracer transport of hundreds of tracers, e.g., in the chemistry version of the Community Atmosphere Model, is still a performance bottleneck. Therefore, we consider two conservative semi-Lagrangian schemes. Both are designed to be multi-tracer efficient, third order accurate, and allow significantly longer time steps than explicit Eulerian formulations. We address the difficulties arising on the cubed-sphere projection and on parallel computers and show the high scalability of our approach. Additionally, we use the two schemes for the transport of passive tracers in a dynamical core and compare our results with a current spectral element tracer transport advection used by the High-Order Method Modeling Environment.

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Effects of Localized Grid Refinement on the General Circulation and Climatology in the Community Atmosphere Model

Journal of Climate ◽

10.1175/jcli-d-14-00599.1 ◽

2015 ◽

Vol 28 (7) ◽

pp. 2777-2803 ◽

Cited By ~ 31

Author(s):

Colin M. Zarzycki ◽

Christiane Jablonowski ◽

Diana R. Thatcher ◽

Mark A. Taylor

Keyword(s):

General Circulation ◽

Large Scale ◽

Precipitable Water ◽

Atmospheric Model ◽

Spectral Element ◽

Horizontal Resolution ◽

Department Of Energy ◽

Extreme Precipitation Events ◽

Community Atmosphere Model ◽

Atmosphere Model

Abstract Using the spectral element (SE) dynamical core within the National Center for Atmospheric Research–Department of Energy Community Atmosphere Model (CAM), a regionally refined nest at 0.25° (~28 km) horizontal resolution located over the North Atlantic is embedded within a global 1° (~111 km) grid. A 23-yr simulation using Atmospheric Model Intercomparison Project (AMIP) protocols and default CAM, version 5, physics is compared to an identically forced run using the global 1° (~111 km) grid without refinement. The addition of a refined patch over the Atlantic basin does not noticeably affect the global circulation. In the area where the refinement is located, large-scale precipitation increases with the higher resolution. This increase is partly offset by a decrease in precipitation resulting from convective parameterizations, although total precipitation is also slightly higher at finer resolutions. Equatorial waves are not significantly impacted when traversing multiple grid spacings. Despite the grid transition region bisecting northern Africa, local zonal jets and African easterly wave activity are highly similar in both simulations. The frequency of extreme precipitation events increases with resolution, although this increase is restricted to the refined patch. Topography is better resolved in the nest as a result of finer grid spacing. The spatial patterns of variables with strong orographic forcing (such as precipitation, cloud, and precipitable water) are improved with local refinement. Additionally, dynamical features, such as wind patterns, associated with steep terrain are improved in the variable-resolution simulation when compared to the uniform coarser run.

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The implementation of the finite-volume dynamical core in the community atmosphere model

Journal of Computational and Applied Mathematics ◽

10.1016/j.cam.2006.04.015 ◽

2007 ◽

Vol 203 (2) ◽

pp. 387-396 ◽

Cited By ~ 1

Author(s):

William B. Sawyer ◽

Arthur A. Mirin

Keyword(s):

Finite Volume ◽

Dynamical Core ◽

Community Atmosphere Model ◽

Atmosphere Model

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CAM-SE–CSLAM: Consistent Coupling of a Conservative Semi-Lagrangian Finite-Volume Method with Spectral Element Dynamics

Monthly Weather Review ◽

10.1175/mwr-d-16-0258.1 ◽

2017 ◽

Vol 145 (3) ◽

pp. 833-855 ◽

Cited By ~ 10

Author(s):

Peter Hjort Lauritzen ◽

Mark A. Taylor ◽

James Overfelt ◽

Paul A. Ullrich ◽

Ramachandran D. Nair ◽

...

Keyword(s):

Finite Volume ◽

Search Algorithm ◽

Control Volume ◽

Spectral Element ◽

Volume Transport ◽

Finite Volume Scheme ◽

Tracer Transport ◽

Courant Number ◽

Dynamical Core ◽

Community Atmosphere Model

An algorithm to consistently couple a conservative semi-Lagrangian finite-volume transport scheme with a spectral element (SE) dynamical core is presented. The semi-Lagrangian finite-volume scheme is the Conservative Semi-Lagrangian Multitracer (CSLAM), and the SE dynamical core is the National Center for Atmospheric Research (NCAR)’s Community Atmosphere Model–Spectral Elements (CAM-SE). The primary motivation for coupling CSLAM with CAM-SE is to accelerate tracer transport for multitracer applications. The coupling algorithm result is an inherently mass-conservative, shape-preserving, and consistent (for a constant mixing ratio, the CSLAM solution reduces to the SE solution for air mass) transport that is efficient and accurate. This is achieved by first deriving formulas for diagnosing SE airmass flux through the CSLAM control volume faces. Thereafter, the upstream Lagrangian CSLAM areas are iteratively perturbed to match the diagnosed SE airmass flux, resulting in an equivalent upstream Lagrangian grid that spans the sphere without gaps or overlaps (without using an expensive search algorithm). This new CSLAM algorithm is not specific to airmass fluxes provided by CAM-SE but applies to any airmass fluxes that satisfy the Lipshitz criterion and for which the Courant number is less than one.

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Performance analysis of fully explicit and fully implicit solvers within a spectral element shallow-water atmosphere model

The International Journal of High Performance Computing Applications ◽

10.1177/1094342017736373 ◽

2017 ◽

Vol 33 (2) ◽

pp. 268-284 ◽

Cited By ~ 2

Author(s):

Katherine J Evans ◽

Richard K Archibald ◽

David J Gardner ◽

Matthew R Norman ◽

Mark A Taylor ◽

...

Keyword(s):

Shallow Water ◽

Message Passing Interface ◽

Spectral Element ◽

Processing Unit ◽

Spectral Order ◽

Dynamical Core ◽

Computational Performance ◽

Implicit Solvers ◽

Trade Offs ◽

Atmosphere Model

Explicit Runge–Kutta methods and implicit multistep methods utilizing a Newton–Krylov nonlinear solver are evaluated for a range of configurations of the shallow-water dynamical core of the spectral element community atmosphere model to evaluate their computational performance. These configurations are designed to explore the attributes of each method under different but relevant model usage scenarios including varied spectral order within an element, static regional refinement, and scaling to the largest problem sizes. This analysis is performed within the shallow-water dynamical core option of a full climate model code base to enable a wealth of simulations for study, with the aim of informing solver development within the more complete hydrostatic dynamical core used for climate research. The limitations and benefits to using explicit versus implicit methods, with different parameters and settings, are discussed in light of the trade-offs with Message Passing Interface (MPI) communication and memory and their inherent efficiency bottlenecks. Given the performance behavior across the configurations analyzed here, the recommendation for future work using the implicit solvers is conditional based on scale separation and the stiffness of the problem. For the regionally refined configurations, the implicit method has about the same efficiency as the explicit method, without considering efficiency gains from a preconditioner. The potential for improvement using a preconditioner is greatest for higher spectral order configurations, where more work is shifted to the linear solver. Initial simulations with OpenACC directives to utilize a Graphics Processing Unit (GPU) when performing function evaluations show improvements locally, and that overall gains are possible with adjustments to data exchanges.

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Review of “Altered sub-seasonal predictability of Community Atmosphere Model 5 (CAM5) in CESM 1.2.1 by the choices of dynamical core” by Kim et al.

10.5194/gmd-2020-22-rc1 ◽

2020 ◽

Author(s):

Anonymous

Keyword(s):

Seasonal Predictability ◽

Dynamical Core ◽

Community Atmosphere Model ◽

Atmosphere Model

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The Mean Climate of the Community Atmosphere Model (CAM4) in Forced SST and Fully Coupled Experiments

Journal of Climate ◽

10.1175/jcli-d-12-00236.1 ◽

2013 ◽

Vol 26 (14) ◽

pp. 5150-5168 ◽

Cited By ~ 418

Author(s):

Richard B. Neale ◽

Jadwiga Richter ◽

Sungsu Park ◽

Peter H. Lauritzen ◽

Stephen J. Vavrus ◽

...

Keyword(s):

Freeze Drying ◽

Regional Climate ◽

Cloud Fraction ◽

Trade Wind ◽

Dynamical Core ◽

Model Version ◽

Community Atmosphere Model ◽

Atmosphere Model ◽

Mean Climate ◽

Fully Coupled

Abstract The Community Atmosphere Model, version 4 (CAM4), was released as part of the Community Climate System Model, version 4 (CCSM4). The finite volume (FV) dynamical core is now the default because of its superior transport and conservation properties. Deep convection parameterization changes include a dilute plume calculation of convective available potential energy (CAPE) and the introduction of convective momentum transport (CMT). An additional cloud fraction calculation is now performed following macrophysical state updates to provide improved thermodynamic consistency. A freeze-drying modification is further made to the cloud fraction calculation in very dry environments (e.g., the Arctic), where cloud fraction and cloud water values were often inconsistent in CAM3. In CAM4 the FV dynamical core further degrades the excessive trade-wind simulation, but reduces zonal stress errors at higher latitudes. Plume dilution alleviates much of the midtropospheric tropical dry biases and reduces the persistent monsoon precipitation biases over the Arabian Peninsula and the southern Indian Ocean. CMT reduces much of the excessive trade-wind biases in eastern ocean basins. CAM4 shows a global reduction in cloud fraction compared to CAM3, primarily as a result of the freeze-drying and improved cloud fraction equilibrium modifications. Regional climate feature improvements include the propagation of stationary waves from the Pacific into midlatitudes and the seasonal frequency of Northern Hemisphere blocking events. A 1° versus 2° horizontal resolution of the FV dynamical core exhibits superior improvements in regional climate features of precipitation and surface stress. Improvements in the fully coupled mean climate between CAM3 and CAM4 are also more substantial than in forced sea surface temperature (SST) simulations.

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