Influence of parallel computational uncertainty on simulations of the Coupled General Climate Model

Song, Zhenya; Lei, Xiaoyan; Wang, Chunzai

doi:10.5194/gmd-5-313-2012

Cited by 15 publications

(14 citation statements)

References 5 publications

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“…Song et al, 2012) and can be problematic: Fig. 21 shows results from two "identical" integrations applying the default (but rather aggressive) Intel fp-model compiler option.…”

Section: Computational Uncertaintymentioning

confidence: 99%

MOMBA 1.1 – a high-resolution Baltic Sea configuration of GFDL's Modular Ocean Model

2014

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Abstract. We present a new coupled ocean-circulation-ice model configuration of the Baltic Sea. The model features, contrary to most existing configurations, a high horizontal resolution of ≈ 1 nautical mile (≈ 1.85 km), which is eddyresolving over much of the domain. The vertical discretisation comprises a total of 47 vertical levels. Results from a 1987 to 1999 hindcast simulation show that the model's fidelity is competitive. As suggested by a comparison with sea surface temperatures observed from space, this applies especially to near-surface processes. Hence, the configuration is well suited to serve as a nucleus of a fully fledged coupled ocean-circulation-biogeochemical model (which is yet to be developed). A caveat is that the model fails to reproduce major inflow events. We trace this back to spurious vertical circulation patterns at the sills which may well be endemic to high-resolution models based on geopotential coordinates. Further, we present indications that -so far neglected -eddy/wind effects exert significant control on windinduced up-and downwelling.

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“…Song et al, 2012) and can be problematic: Fig. 21 shows results from two "identical" integrations applying the default (but rather aggressive) Intel fp-model compiler option.…”

Section: Computational Uncertaintymentioning

confidence: 99%

MOMBA 1.1 – a high-resolution Baltic Sea configuration of GFDL's Modular Ocean Model

2014

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“…FGOALS-g2 is a fully coupled CSM consisting of the atmosphere model the Grid-point Atmospheric Model of IAP LASG version 2 (GAMIL2) (Li et al, 2013b), ocean model LASG/IAP Climate System Ocean Model Version 2 (LI-COM2) (Liu et al, 2004), land surface model Community Land Model Version 3 (CLM3) (Oleson et al, 2004), and an improved version (Wang et al, 2009;Liu, 2010) of the sea ice model Los Alamos Sea Ice Model version 4 (CICE4) (http://oceans11.lanl.gov/trac/CICE). It participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) and is widely used for scientific research.…”

Section: Models and Simulationsmentioning

confidence: 99%

“…The first challenge concerns reproducibility of simulation results. Due to the chaotic nature of the climate system, more and more studies have shown that trivial round-off errors can trigger significant changes in simulation results of Earth system modeling (Hong et al, 2013;Liu et al, 2015b;Song et al, 2012). Due to the differences of performance optimization schemes among different compiling setups, a change of compiling setups potentially introduces round-off errors.…”

Section: Introductionmentioning

confidence: 99%

Bitwise identical compiling setup: prospective for reproducibility and reliability of Earth system modeling

Ping

Yang

et al. 2016

Geosci. Model Dev.

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Reproducibility and reliability are fundamental principles of scientific research. A compiling setup that includes a specific compiler version and compiler flags is an essential technical support for Earth system modeling. With the fast development of computer software and hardware, a compiling setup has to be updated frequently, which challenges the reproducibility and reliability of Earth system modeling. The existing results of a simulation using an original compiling setup may be irreproducible by a newer compiling setup because trivial round-off errors introduced by the change in compiling setup can potentially trigger significant changes in simulation results. Regarding the reliability, a compiler with millions of lines of code may have bugs that are easily overlooked due to the uncertainties or unknowns in Earth system modeling. To address these challenges, this study shows that different compiling setups can achieve exactly the same (bitwise identical) results in Earth system modeling, and a set of bitwise identical compiling setups of a model can be used across different compiler versions and different compiler flags. As a result, the original results can be more easily reproduced; for example, the original results with an older compiler version can be reproduced exactly with a newer compiler version. Moreover, this study shows that new test cases can be generated based on the differences of bitwise identical compiling setups between different models, which can help detect software bugs in the codes of models and compilers and finally improve the reliability of Earth system modeling.Published by Copernicus Publications on behalf of the European Geosciences Union.

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“…The first challenge is that new heavy burdens would be introduced to scientists. As bitwise results are determined by the whole simulation setting (including the model code, input data, parameter setting, computing environment, etc., Ford et al, 2012) and are very sensitive to round-off errors resulting from the computing environment 10 (Monniaux, 2008;Song et al, 2012;Hong et al, 2013), it requires original scientists to preserve the whole simulation setting and fellow scientists to recreate almost exactly the same simulation setting during a reproduction.…”

Section: Introductionmentioning

confidence: 99%

Enhancement for bitwise identical reproducibility of Earth system modeling on the C-Coupler platform

Ping

Zhang

et al. 2015

Preprint

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Abstract. Reliable numerical simulation plays a critical role in climate change study. The reliability includes bitwise identical reproducibility, i.e. bitwise identical result of numerical simulation can be reproduced. It is important to Earth system modeling and has already been used intra modeling groups for the model development. However, it is rarely considered in a wider range even worldwide. To help achieve the worldwide bitwise identical reproducibility, we introduce the detailed implementations for the bitwise identical reproducibility on the Community Coupler (C-Coupler) platform, a uniform runtime software environment that configures, builds and runs the models in the same manner. Moreover, we share a series of experiences and suggestions regarding the bitwise identical reproducibility. We believe that these implementations, experiences and suggestions can be easily extended to other model software platforms and can prospectively advance the model development and scientific researches in the future.

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Influence of parallel computational uncertainty on simulations of the Coupled General Climate Model

Cited by 15 publications

References 5 publications

MOMBA 1.1 – a high-resolution Baltic Sea configuration of GFDL's Modular Ocean Model

MOMBA 1.1 – a high-resolution Baltic Sea configuration of GFDL's Modular Ocean Model

Bitwise identical compiling setup: prospective for reproducibility and reliability of Earth system modeling

Enhancement for bitwise identical reproducibility of Earth system modeling on the C-Coupler platform

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