The Finite-volumE Sea ice–Ocean Model (FESOM2)

Danilov, Sergey; Sidorenko, Dmitry; Wang, Qiang; Jung, Thomas

doi:10.5194/gmd-10-765-2017

Cited by 143 publications

(192 citation statements)

References 51 publications

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“…Surface water 14 C paleorecords typically originate from continental margins, marginal seas, or tropical lagoons which are not properly resolved by coarse‐resolution ocean models and may result in regional model biases. The resolution problem could be overcome by the next generation of 14 C‐equipped ocean circulation models, either through nesting approaches or by means of global multiresolution models with unstructured meshes [e.g., Danilov et al ., ].…”

Section: Discussionmentioning

confidence: 99%

Marine radiocarbon reservoir age simulations for the past 50,000 years

Butzin

Köhler

Lohmann

2017

Geophysical Research Letters

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Radiocarbon (14C) dating calibration for the last glacial period largely relies on cross‐dated marine 14C records. However, marine reservoirs are isotopically depleted with respect to the atmosphere and therefore have to be corrected by the Marine Radiocarbon Ages of surface waters (MRAs), whose temporal variabilities are largely unknown. Here we present simulations of the spatial and temporal variability in MRAs using a three‐dimensional ocean circulation model covering the past 50,000 years. Our simulations are compared to reconstructions of past surface ocean Δ14C. Running the model with different climatic boundary conditions, we find that low‐latitude to midlatitude MRAs have varied between 400 and 1200 14C years, with values of about 780 14C years at the Last Glacial Maximum. Reservoir ages exceeding 2000 14C years are simulated in the polar oceans. Our simulation results can be used as first‐order approximation of the MRA variability in future radiocarbon calibration efforts.

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Section: Discussionmentioning

confidence: 99%

Marine radiocarbon reservoir age simulations for the past 50,000 years

Butzin

Köhler

Lohmann

2017

Geophysical Research Letters

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“…While Northern Hemisphere sea ice is within the range of observed thicknesses and covers an area which is just slightly too large in the North Atlantic (cf. to Figure 7 of Danilov et al, 2017), Southern Ocean sea ice is generally underestimated by FESOM2, especially in the summer months (see Figure 7 of Danilov et al, 2017). A further reduction of Antarctic sea ice through backscatter is therefore not a desirable outcome.…”

Section: Impact On Sea Icementioning

confidence: 98%

Ocean Kinetic Energy Backscatter Parametrization on Unstructured Grids: Impact on Global Eddy‐Permitting Simulations

Juricke

Danilov

Koldunov

et al. 2020

J Adv Model Earth Syst

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In this study we demonstrate the potential of a kinetic energy backscatter scheme for use in global ocean simulations. Ocean models commonly employ (bi)harmonic eddy viscosities causing excessive dissipation of kinetic energy in eddy-permitting simulations. Overdissipation not only affects the smallest resolved scales but also the generation of eddies through baroclinic instabilities, impacting the entire wave number spectrum. The backscatter scheme returns part of this overdissipated energy back into the resolved flow. We employ backscatter in the FESOM2 multiresolution ocean model with a quasi-uniform 1/4 • mesh. In multidecadal ocean simulations, backscatter increases eddy activity by a factor 2 or more, moving the simulation closer to observational estimates of sea surface height variability. Moreover, mean sea surface height, temperature, and salinity biases are reduced. This amounts to a globally averaged bias reduction of around 10% for each field, which is even larger in the Antarctic Circumpolar Current. However, in some regions such as the coastal Kuroshio, backscatter leads to a slight overenergizing of the flow and, in the Antarctic, to an unrealistic reduction of sea ice. Some of the bias increases can be reduced by a retuning of the model, and we suggest related adjustments to the backscatter scheme. The backscatter simulation is about 2.5 times as expensive as a simulation without backscatter. Most of the increased cost is due to a halving of the time step to accommodate higher simulated velocities. Plain Language SummaryThe weather of the oceans is determined by so-called mesoscale eddies, which carry a large portion of the kinetic energy of ocean currents. They are responsible for the transport of heat and dissolved substances; they can affect the large and fast mean currents of the ocean and interact strongly with the atmosphere above. However, these eddies are not well represented in current ocean and climate models. With this study, we apply a new method to better represent the effect of ocean weather in ocean models. We show that this leads to improvements of the simulation of ocean currents and their variability and reduces biases in ocean temperatures and salinity. While increasing the resolution of ocean models also helps to improve the representation of mesoscale eddies, such a resolution increase is computationally expensive. The new backscatter parametrization can help to save computational costs by allowing improved eddy simulations comparable to much higher resolution.

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“…The present manuscript considers the computational performance and parallel scalability of the unstructured-mesh Finite-volumE Sea ice-Ocean circulation Model (FESOM2.0, Danilov et al (2017)). FESOM2 is based on FESOM1.4 (Wang et al (2014))-the first mature general-circulation model on unstructured mesh developed for climate research applications-but using a faster dynamical core.…”

Section: Introductionmentioning

confidence: 99%

Scalability and some optimization of the Finite-volumE Sea ice-Ocean Model, Version 2.0 (FESOM2)

Koldunov¹,

Aizinger²,

Rakowsky³

et al. 2019

Preprint

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Abstract. A study of the scalability of the Finite-volumE Sea ice-Ocean circulation Model, Version 2.0 (FESOM2), the first mature global model of its kind formulated on unstructured meshes, is presented. This study includes an analysis of main computational kernels with a special focus on bottlenecks in parallel scalability. Several model enhancements, improving this scalability for large numbers of processes, are described and tested. Model grids at different resolutions are used on four HPC systems with differing computation and communication hardware to demonstrate model's scalability and throughput. Furthermore, strategies for improvements in parallel performance are presented and assessed. We show that in terms of throughput FESOM2.0 is on par with the state-of-the-art structured ocean models and in realistic eddy resolving configuration (1/10° resolution) can produce about 16 years per day on 14 000 cores. This suggests that unstructured-mesh models are becoming extremely competitive tools in high-resolution climate modelling. It is shown that main bottlenecks of FESOM parallel scalability are the two-dimensional components of the model, namely the computations of external (barotropic) mode and the sea-ice model. It is argued that these bottlenecks are shared with other general ocean circulation models.

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The Finite-volumE Sea ice–Ocean Model (FESOM2)

Cited by 143 publications

References 51 publications

Marine radiocarbon reservoir age simulations for the past 50,000 years

Marine radiocarbon reservoir age simulations for the past 50,000 years

Ocean Kinetic Energy Backscatter Parametrization on Unstructured Grids: Impact on Global Eddy‐Permitting Simulations

Scalability and some optimization of the Finite-volumE Sea ice-Ocean Model, Version 2.0 (FESOM2)

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