Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
doi:10.5194/gmd-2016-296
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Development and technical paper
22 Dec 2016
Review status
A revision of this discussion paper is under review for the journal Geoscientific Model Development (GMD).
Locally-orthogonal unstructured grid-generation for general circulation modelling on the sphere*
Darren Engwirda 1Department of Earth, Atmospheric and Planetary Sciences, Room 54-1517, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307
2NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 USA
Abstract. An algorithm for the generation of non-uniform, locally-orthogonal staggered unstructured spheroidal grids is described. This technique is designed to generate high-quality staggered Voronoi/Delaunay dual meshes appropriate for general circulation modelling on the sphere, including applications to atmospheric simulation, ocean-modelling and numerical weather prediction. Using a recently developed Frontal-Delaunay refinement technique, a method for the construction of unstructured spheroidal Delaunay triangulations is introduced. A locally-orthogonal polygonal grid, derived from the associated Voronoi diagram, is computed as the staggered dual. It is shown that use of the Delaunay-refinement technique allows for the generation of unstructured grids that satisfy a priori constraints on minimum mesh-quality. The initial staggered Voronoi/Delaunay tessellation is iteratively improved through hill-climbing optimisation techniques. Such an approach is shown to produce grids with very high element quality and smooth grading characteristics, while imposing relatively low computational expense. Initial results are presented for a selection of uniform and non-uniform spheroidal grids appropriate for high-resolution, multi-scale general circulation modelling. The use of user-defined mesh-spacing functions to generate smoothly graded, non-uniform grids for multi-resolution type studies is discussed in detail.

Citation: Engwirda, D.: Locally-orthogonal unstructured grid-generation for general circulation modelling on the sphere*, Geosci. Model Dev. Discuss., doi:10.5194/gmd-2016-296, in review, 2016.
Darren Engwirda
Darren Engwirda
Darren Engwirda

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Short summary
A new algorithm for the generation of very high-quality staggered unstructured grids for multi-resolution ocean and atmospheric modelling is described. Through use of unstructured triangulation and grid-optimisation techniques, it is shown that meshes satisfying a number of important a priori grid-quality constraints can be constructed. This new algorithm is expected to be of interest to both developers and users of unstructured general circulation models.
A new algorithm for the generation of very high-quality staggered unstructured grids for...
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