Assessing the scales in numerical weather and climate predictions: will exascale be the rescue?

Neumann, Philipp; Dueben, Peter; Adamidis, Panagiotis; Bauer, Péter; Brück, Matthias; Kornblueh, Luis; Klocke, Daniel; Stevens, Björn; Wedi, Nils; Biercamp, Joachim

doi:10.1098/rsta.2018.0148

Cited by 72 publications

(72 citation statements)

References 30 publications

(45 reference statements)

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“…Table 1 of Schulthess et al 2019) and a horizontal grid spacing of 1 km on the currently largest supercomputer available would fall short of the 1 SYPD target by approximately a factor of 20 . A recent study by Neumann et al (2019) reports a shortfall of a factor of 30, extrapolating results from the ICON model at 5 km grid spacing and assuming perfect weak scaling.…”

Section: E579mentioning

confidence: 79%

“…However, what resolution will actually be needed for the later purpose is not yet fully understood. On the one hand, convective cloud processes (dynamics, turbulence, and microphysics) occur on scales that are not fully resolved at kilometer resolution (Skamarock 2004;Neumann et al 2019;Panosetti et al 2019b). On the other hand, studies have indicated that there is some bulk convergence at grid resolutions around 2 km, that is, the feedbacks between convective clouds and the larger-scale flow are partly captured at resolutions at which the structural details of the cloud field are not yet fully resolved (Langhans et al 2012;Harvey et al 2017;Ito et al 2017;Panosetti et al 2019Panosetti et al , 2020.…”

mentioning

confidence: 99%

“…On the other hand, studies have indicated that there is some bulk convergence at grid resolutions around 2 km, that is, the feedbacks between convective clouds and the larger-scale flow are partly captured at resolutions at which the structural details of the cloud field are not yet fully resolved (Langhans et al 2012;Harvey et al 2017;Ito et al 2017;Panosetti et al 2019Panosetti et al , 2020. Following Schulthess et al (2019) and Neumann et al (2019), we thus assume that a global resolution of 1 km is a suitable near-term target. Thus, further improvements in the parameterizations of the turbulence and microphysical processes appear essential, as these processes will remain poorly resolved.…”

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confidence: 99%

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Kilometer-Scale Climate Models: Prospects and Challenges

Schär

Fuhrer

Arteaga

et al. 2020

Bulletin of the American Meteorological Society

134

122

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Currently major efforts are underway toward refining the horizontal resolution (or grid spacing) of climate models to about 1 km, using both global and regional climate models (GCMs and RCMs). Several groups have succeeded in conducting kilometer-scale multiweek GCM simulations and decadelong continental-scale RCM simulations. There is the well-founded hope that this increase in resolution represents a quantum jump in climate modeling, as it enables replacing the parameterization of moist convection by an explicit treatment. It is expected that this will improve the simulation of the water cycle and extreme events and reduce uncertainties in climate change projections. While kilometer-scale resolution is commonly employed in limitedarea numerical weather prediction, enabling it on global scales for extended climate simulations requires a concerted effort. In this paper, we exploit an RCM that runs entirely on graphics processing units (GPUs) and show examples that highlight the prospects of this approach. A particular challenge addressed in this paper relates to the growth in output volumes. It is argued that the data avalanche of high-resolution simulations will make it impractical or impossible to store the data. Rather, repeating the simulation and conducting online analysis will become more efficient. A prototype of this methodology is presented. It makes use of a bit-reproducible model version that ensures reproducible simulations across hardware architectures, in conjunction with a data virtualization layer as a common interface for output analyses. An assessment of the potential of these novel approaches will be provided.

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Section: E579mentioning

confidence: 79%

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confidence: 99%

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confidence: 99%

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Kilometer-Scale Climate Models: Prospects and Challenges

Schär

Fuhrer

Arteaga

et al. 2020

Bulletin of the American Meteorological Society

134

122

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“…It is well known from earlier studies that SST features on these scales are important to simulate the structure and movement of cyclones (e.g., [76,77]), their deepening rate (e.g., [78,79]), and maybe even the frequency of lightning [80,81]. Nevertheless, the computational challenge of scaling up these results (weather) to long global simulations (climate), or ensemble of these, is very significant [82,83] and only begins to be addressed in atmosphere-only set-ups (e.g., [84]).…”

Section: Small-scale Oceanic Forcingmentioning

confidence: 99%

Simulating the Midlatitude Atmospheric Circulation: What Might We Gain From High-Resolution Modeling of Air-Sea Interactions?

Czaja

Frankignoul

Minobe

et al. 2019

Curr Clim Change Rep

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Purpose of Review To provide a snapshot of the current research on the oceanic forcing of the atmospheric circulation in midlatitudes and a concise update on previous review papers. Recent Findings Atmospheric models used for seasonal and longer timescales predictions are starting to resolve motions so far only studied in conjunction with weather forecasts. These phenomena have horizontal scales of~10-100 km which coincide with energetic scales in the ocean circulation. Evidence has been presented that, as a result of this matching of scale, oceanic forcing of the atmosphere was enhanced in models with 10-100 km grid size, especially at upper tropospheric levels. The robustness of these results and their underlying mechanisms are however unclear. Summary Despite indications that higher resolution atmospheric models respond more strongly to sea surface temperature anomalies, their responses are still generally weaker than those estimated empirically from observations. Coarse atmospheric models (grid size greater than 100 km) will miss important signals arising from future changes in ocean circulation unless new parameterizations are developed. Keywords Ocean-atmosphere interactions. High-resolution climate modeling. Midlatitude climate dynamics. Sea surface temperature anomalies. This article is part of the Topical Collection on Mid-latitude Processes and Climate Change * A. Czaja

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“…In recent years, studies have demonstrated the added value of explicitly resolved convection also for the simulation of precipitation in climate simulations (e.g., Hohenegger et al 2008;Kendon et al 2014;Ban et al 2014;Leutwyler et al 2017). Recent advances in computing power and architecture made it possible to increase the domain size and integration time allowing for decade-long continentalscale climate simulations at convection-resolving resolution (e.g., Leutwyler et al 2016;Prein et al 2017;Hentgen et al 2019) and even global-scale convection-resolving simulations have been conducted over week-long periods (e.g., Miyamoto et al 2013;Bretherton and Khairoutdinov 2015;Fuhrer et al 2018;Neumann et al 2019).…”

Section: Introductionmentioning

confidence: 99%

The Influence of the Resolution of Orography on the Simulation of Orographic Moist Convection

Heim

Panosetti

Schlemmer

et al. 2020

Monthly Weather Review

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Currently, major efforts are under way to refine the horizontal resolution of weather and climate models to kilometer-scale grid spacing (Δx). Besides refining the representation of the atmospheric dynamics and enabling the use of explicit convection, this will also provide higher resolution in the representation of orography. This study investigates the influence of these resolution increments on the simulation of orographic moist convection. Nine days of fair-weather thermally driven flow over the Alps are analyzed. Two sets of simulations with the COSMO model are compared, each consisting of three runs at Δx of 4.4, 2.2, and 1.1 km: one set using a fixed representation of orography at a resolution of 8.8 km, and one with varying representation at the resolution of the computational mesh. The spatial distribution of precipitation during daytime is only marginally affected by the orographic details, but nighttime convection to the south of the Alps—triggered by cold-air outflow from the valleys—is very sensitive to orography and precipitation is enhanced if more detailed orography is provided. During daytime, the onset of precipitation is delayed. The amplitude of the diurnal cycle of precipitation is reduced, even though more moisture converges toward the Alpine region during the afternoon. The hereby accumulated moisture sustains precipitation during the evening and nighttime over the surrounding plains. For these differences, the effects of changes in orographic detail are more important than changes in grid spacing. In addition, the individual convective cells are weaker, but their number increases with higher resolved orography.

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Assessing the scales in numerical weather and climate predictions: will exascale be the rescue?

Cited by 72 publications

References 30 publications

Kilometer-Scale Climate Models: Prospects and Challenges

Kilometer-Scale Climate Models: Prospects and Challenges

Simulating the Midlatitude Atmospheric Circulation: What Might We Gain From High-Resolution Modeling of Air-Sea Interactions?

The Influence of the Resolution of Orography on the Simulation of Orographic Moist Convection

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