Exploring a Lower‐Resolution Physics Grid in CAM‐SE‐CSLAM

Herrington, Adam; Lauritzen, P. H.; Reed, Kevin A.; Goldhaber, Steve; Eaton, Brian

doi:10.1029/2019ms001684

Cited by 23 publications

(33 citation statements)

References 42 publications

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“…The preferred way to address the grid imprinting is to completely remove or mask the inhomogeneity that is inherent between the nodes of the GLL grid. Herrington, Lauritzen, Reed, et al () and Herrington, Lauritzen, Taylor, et al () did this by moving the physics calculations to a quasi‐equal‐area finite volume grid. We have implemented a scheme inspired by their work that uses a 2

\times

2 grid of finite volume cells for each spectral element and an interpolation method that does not require information from neighboring elements.…”

Section: Discussionmentioning

confidence: 99%

Initial Results From the Super‐Parameterized E3SM

Hannah

Jones

Hillman

et al. 2020

J Adv Model Earth Syst

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Results from the new Department of Energy super-parameterized (SP) Energy ExascaleEarth System Model (SP-E3SM) are analyzed and compared to the traditionally parameterized E3SMv1 and previous studies using SP models. SP-E3SM is unique in that it utilizes Graphics Processing Unit hardware acceleration, cloud resolving model mean-state acceleration, and reduced radiation to dramatically increase the model throughput and allow decadal experiments at 100-km external resolution. It also differs from other SP models by using a spectral element dynamical core on a cubed-sphere grid and a finer vertical grid with a higher model top. Despite these differences, SP-E3SM generally reproduces the behavior of other SP models. Tropical wave variability is improved relative to E3SM, including the emergence of a Madden-Julian Oscillation and a realistic slowdown of Moist Kelvin Waves. However, the distribution of precipitation exhibits indicates an overly frequent occurrence of rain rates less than 1 mm day −1 , and while the timing of diurnal rainfall shows modest improvements the signal is not as coherent as observations. A notable grid imprinting bias is identified in the precipitation field and attributed to a unique feedback associated with the interactions between the explicit cloud resolving model convection and the spectral element grid structure. Spurious zonal mean column water tendencies due to grid imprinting are quantified-while negligible for the conventionally parameterized E3SM, they become large with super-parameterization, approaching 10% of the physical tendencies. The implication is that finding a remedy to grid imprinting will become especially important as spectral element dynamical cores begin to be combined with explicitly resolved convection.

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\times

2 grid of finite volume cells for each spectral element and an interpolation method that does not require information from neighboring elements.…”

Section: Discussionmentioning

confidence: 99%

Initial Results From the Super‐Parameterized E3SM

Hannah

Jones

Hillman

et al. 2020

J Adv Model Earth Syst

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show abstract

“…However, it is suggested that the overwhelming support for the h = 1/3 exponent in the second‐order structure function is only relevant for horizontal scales of the order of 100 km and less (Lindborg, 1999; Cho and Lindborg, 2001). This mesoscale regime is only marginally resolved in the highest resolution simulation,

Δ x = 27.8

km ( ne 120), since CAM‐SE‐CSLAM has an effective resolution in the range of 5–

10 Δ x

(Herrington et al ., 2019). The nonexistence of h = 1/3 in the

Δ x = 27.8

km simulation is verified through analyzing the slope of the kinetic energy spectrum

- β

, which is in duality with the second‐order structure function through the Weiner–Khinchine theorem.…”

Section: Discussionmentioning

confidence: 99%

“…The coupled system, referred to as CAM‐SE‐CSLAM, conserves energy and mass and preserves linear correlations between two reactive species to within machine precision (Herrington et al ., 2018). A coarser physics grid, containing 5/9 fewer degrees of freedom than the dynamical core grid, is also available as part of the CAM‐SE‐CSLAM package (Herrington et al ., 2019). This lower‐resolution physics grid is used in this study, but only as a member of a perturbed parameter ensemble and not in the control convergence experiment.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

On resolution sensitivity in the Community Atmosphere Model

Herrington

Reed

2020

Quart J Royal Meteoro Soc

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Advances in high-performance computing make it possible to run atmospheric general circulation models (AGCMs) over an increasingly wider range of grid resolutions, using either globally uniform or variable-resolution grids. In principle, this is an exciting opportunity to resolve atmospheric process and scales in a global model and in unprecedented detail, but in practice this grid flexibility is incompatible with the non-or weakly converging solutions with increasing horizontal resolution that have long characterized AGCMs. In the the Community Atmosphere Model (CAM), there are robust sensitivities to horizontal resolution that have persisted since the model was first introduced over thirty years ago; the atmosphere progressively dries and becomes less cloudy with resolution, and parametrized deep convective precipitation decreases at the expense of stratiform precipitation. This study documents a convergence experiment using CAM, version 6, and argues that a unifying cause, the sensitivity of resolved dynamical modes to native grid resolution, feeds back into other model components and explains these robust sensitivities to resolution. The increasing magnitudes of resolved vertical velocities with resolution are shown to fit an analytic scaling derived for the equations of motion at hydrostatic scales. This trend in vertical velocities results in an increase in resolved upward moisture fluxes at cloud base, balanced by an increase in stratiform precipitation rates with resolution. Compensating, greater magnitude subsiding motion with resolution has previously been shown to dry out the atmosphere and reduce cloud cover. Here, it is shown that both the increase in condensational heating from stratiform cloud formation and greater subsidence drying contribute to an increase in atmospheric stability with resolution, reducing the activity of parametrized convection. The impact of changing the vertical velocity field with native grid resolution cannot be ignored in any effort to recover convergent solutions in AGCMs, and, in particular, the development of scale-aware physical parametrizations.

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“…It is not uncommon to apply different resolutions for different components of a numerical model. For example, Herrington et al (2019) showed that a high-resolution dynamical core using low-resolution parameterizations generates satisfactory results.…”

Section: Introductionmentioning

confidence: 99%

Extending Legacy Climate Models by Adaptive Mesh Refinement for Single Component Tracer Transport: A Case Study with ECHAM6-HAMMOZ (ECHAM30-HAM23-MOZ10)

Chen¹,

Simon²,

Behrens³

2020

Preprint

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Abstract. Model error in climate models depends on mesh resolution among other factors. While global refinement of the computational mesh is often not feasible computationally, Adaptive Mesh Refinement (AMR) can be an option for spatially localized features. Creating a climate model with AMR has been prohibitive so far. We use AMR in one single model component, namely the tracer transport scheme.M Particularly, we integrate AMR into the tracer transport module of the atmospheric model ECHAM6 and test our implementation in several idealized scenarios and in a realistic application scenario (dust transport). To achieve this goal, we modify the Flux-Form Semi-Lagrangian (FFSL) transport scheme in ECHAM6 such that we can use it on adaptive meshes while retaining all important properties such as mass conservation of the original FFSL implementation. Our proposed AMR scheme is dimensionally split and ensures that high-resolution information is always propagated on (locally) highly resolved meshes. We also introduce a data structure that can accommodate an adaptive Gaussian grid. We demonstrate that our AMR scheme improves both accuracy and efficiency compared to the original FFSL scheme. More importantly, our approach improves the representation of transport processes in ECHAM6 for coarse resolution simulations. Hence, this paper suggests that we can overcome the overhead of developing a fully adaptive earth system model by integrating AMR into single components while leaving data structures of the dynamical core untouched. This enables studies to retain well-tested and complex legacy code of existing models while still improving the accuracy of specific components, without sacrificing efficiency.

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Exploring a Lower‐Resolution Physics Grid in CAM‐SE‐CSLAM

Cited by 23 publications

References 42 publications

Initial Results From the Super‐Parameterized E3SM

Initial Results From the Super‐Parameterized E3SM

On resolution sensitivity in the Community Atmosphere Model

Extending Legacy Climate Models by Adaptive Mesh Refinement for Single Component Tracer Transport: A Case Study with ECHAM6-HAMMOZ (ECHAM30-HAM23-MOZ10)

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