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Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
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© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: model evaluation paper 07 Jul 2020

Submitted as: model evaluation paper | 07 Jul 2020

Review status
This preprint is currently under review for the journal GMD.

Configuration and Evaluation of a Global Unstructured Mesh Model based on the Variable-Resolution Approach

Yihui Zhou1,2, Yi Zhang3, Jian Li3, Rucong Yu3, and Zhuang Liu4 Yihui Zhou et al.
  • 1State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
  • 2University of Chinese Academy of Sciences, Beijing, China
  • 3State Key Laboratory of Severe Weather (LaSW), Chinese Academy of Meteorological Sciences, China Meteorological Administration, Beijing, China
  • 4National Supercomputing Center in Wuxi, Jiangsu, China

Abstract. Targeting a long-term effort towards a global weather and climate model with a local refinement function, this study systematically configures and evaluates the performance of an unstructured model based on the variable-resolution (VR) approach. Aided by the idealized dry- and moist-atmosphere tests, the model performance is examined in an intermediate degree of complexity. The dry baroclinic wave simulations suggest that the 3D VR-model can reproduce comparable solutions in the refined regions as a fine-resolution quasi-uniform (QU) mesh model, although the global errors increase. The variation of the mesh resolution in the transition zone does not adversely affect the wave pattern. In the coarse-resolution area, the VR model simulates a similar wave distribution to the low-resolution QU model. Two multi-region refinement approaches, including the hierarchical and polycentric refinement modes, further testify the model performance under a more challenging environment. The moist idealized tropical cyclone test further enables us to examine the model ability in terms of resolving fine-scale structures. It is found that the VR model can have the tropical cyclone stably pass the transition zone in various configurations. A series of sensitivity tests examines the model performance in a hierarchical refinement mode, and the solutions exhibit consistency even when the VR mesh is slightly perturbed by one of the three parameters that control the density function. Moreover, only the finest resolution has a dominant impact on the fine-scale structures in the refined region. The tropical cyclone, starting from the 2nd-refinement region and passing through the inner transition zone, gets intensified and possesses a smaller area coverage in the refined regions, as compared to the QU-mesh model that has the same number of grid points. Such variations are consistent with the behavior that one may observe when uniformly refining the QU-mesh model. Besides the horizontal resolution, the intensity of the tropical cyclone is also influenced by the Smagorinsky horizontal diffusion coefficient. The VR model exhibits higher sensitivity in this regard, suggesting the importance of parameter tuning and proper model configurations.

Yihui Zhou et al.

Interactive discussion

Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Yihui Zhou et al.

Data sets

Quasi-uniform and Variable-resolution grid data for GRIST GRIST-Dev

Model code and software

Frozen code version of ParGRIST-A20-0705 (including running and postprocessing scripts) GRIST-Dev

Yihui Zhou et al.


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Latest update: 28 Oct 2020
Publications Copernicus
Short summary
The variable-resolution modeling approach is developed to preserve the benefit of high-resolution modeling for certain regions at a lower computational cost. This paper presents the configuration and evaluation of a global atmospheric model with various refinement approaches. In the idealized dry- and moist-atmosphere test cases, the VR model is able to resolve fine-scale fluid structures. Model sensitivity is further examined to figure out the impact of the model and mesh-generation parameters.
The variable-resolution modeling approach is developed to preserve the benefit of...