Topography-based local spherical Voronoi grid refinement on classical and moist shallow-water finite-volume models

<p>Locally refined grids for global atmospheric models are attractive since they are expected to provide an alternative to solve local phenomena without the requirement of a global high-resolution uniform grid, whose computational cost may be prohibitive. Spherical centroidal Voronoi tessellat...

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Autores principales:	L. F. Santos, P. S. Peixoto
Formato:	article
Lenguaje:	EN
Publicado:	Copernicus Publications 2021
Materias:	Geology QE1-996.5
Acceso en línea:	https://doaj.org/article/61d6da19978e4d57925a0f07571741c7
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spelling	oai:doaj.org-article:61d6da19978e4d57925a0f07571741c72021-11-16T06:32:06ZTopography-based local spherical Voronoi grid refinement on classical and moist shallow-water finite-volume models10.5194/gmd-14-6919-20211991-959X1991-9603https://doaj.org/article/61d6da19978e4d57925a0f07571741c72021-11-01T00:00:00Zhttps://gmd.copernicus.org/articles/14/6919/2021/gmd-14-6919-2021.pdfhttps://doaj.org/toc/1991-959Xhttps://doaj.org/toc/1991-9603<p>Locally refined grids for global atmospheric models are attractive since they are expected to provide an alternative to solve local phenomena without the requirement of a global high-resolution uniform grid, whose computational cost may be prohibitive. Spherical centroidal Voronoi tessellation (SCVT), as used in the atmospheric Model for Prediction Across Scales (MPAS), allows a flexible way to build and work with local refinement. In addition, the Andes Range plays a key role in the South American weather, but it is hard to capture its fine-structure dynamics in global models. This paper describes how to generate SCVT grids that are locally refined in South America and that also capture the sharp topography of the Andes Range by defining a density function based on topography and smoothing techniques. We investigate the use of the mimetic finite-volume scheme employed in the MPAS dynamical core on this grid considering the nonlinear classic and moist shallow-water equations on the sphere. We show that the local refinement, even with very smooth transitions from different resolutions, generates spurious numerical inertia–gravity waves that may even numerically destabilize the model. In the moist shallow-water model, wherein physical processes such as precipitation and cloud formation are included, our results show that the local refinement may generate spurious rain that is not observed in uniform-resolution SCVT grids. Fortunately, the spurious waves originate from small-scale grid-related numerical errors and can therefore be mitigated using fourth-order hyperdiffusion. We exploit a grid geometry-based hyperdiffusion that is able to stabilize spurious waves and has very little impact on the total energy conservation. We show that, in some cases, the clouds are better represented in a variable-resolution grid when compared to a respective uniform-resolution grid with the same number of cells, while in other cases, grid effects can affect the cloud and rain representation.</p>L. F. SantosP. S. PeixotoCopernicus PublicationsarticleGeologyQE1-996.5ENGeoscientific Model Development, Vol 14, Pp 6919-6944 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Geology QE1-996.5
spellingShingle	Geology QE1-996.5 L. F. Santos P. S. Peixoto Topography-based local spherical Voronoi grid refinement on classical and moist shallow-water finite-volume models
description	<p>Locally refined grids for global atmospheric models are attractive since they are expected to provide an alternative to solve local phenomena without the requirement of a global high-resolution uniform grid, whose computational cost may be prohibitive. Spherical centroidal Voronoi tessellation (SCVT), as used in the atmospheric Model for Prediction Across Scales (MPAS), allows a flexible way to build and work with local refinement. In addition, the Andes Range plays a key role in the South American weather, but it is hard to capture its fine-structure dynamics in global models. This paper describes how to generate SCVT grids that are locally refined in South America and that also capture the sharp topography of the Andes Range by defining a density function based on topography and smoothing techniques. We investigate the use of the mimetic finite-volume scheme employed in the MPAS dynamical core on this grid considering the nonlinear classic and moist shallow-water equations on the sphere. We show that the local refinement, even with very smooth transitions from different resolutions, generates spurious numerical inertia–gravity waves that may even numerically destabilize the model. In the moist shallow-water model, wherein physical processes such as precipitation and cloud formation are included, our results show that the local refinement may generate spurious rain that is not observed in uniform-resolution SCVT grids. Fortunately, the spurious waves originate from small-scale grid-related numerical errors and can therefore be mitigated using fourth-order hyperdiffusion. We exploit a grid geometry-based hyperdiffusion that is able to stabilize spurious waves and has very little impact on the total energy conservation. We show that, in some cases, the clouds are better represented in a variable-resolution grid when compared to a respective uniform-resolution grid with the same number of cells, while in other cases, grid effects can affect the cloud and rain representation.</p>
format	article
author	L. F. Santos P. S. Peixoto
author_facet	L. F. Santos P. S. Peixoto
author_sort	L. F. Santos
title	Topography-based local spherical Voronoi grid refinement on classical and moist shallow-water finite-volume models
title_short	Topography-based local spherical Voronoi grid refinement on classical and moist shallow-water finite-volume models
title_full	Topography-based local spherical Voronoi grid refinement on classical and moist shallow-water finite-volume models
title_fullStr	Topography-based local spherical Voronoi grid refinement on classical and moist shallow-water finite-volume models
title_full_unstemmed	Topography-based local spherical Voronoi grid refinement on classical and moist shallow-water finite-volume models
title_sort	topography-based local spherical voronoi grid refinement on classical and moist shallow-water finite-volume models
publisher	Copernicus Publications
publishDate	2021
url	https://doaj.org/article/61d6da19978e4d57925a0f07571741c7
work_keys_str_mv	AT lfsantos topographybasedlocalsphericalvoronoigridrefinementonclassicalandmoistshallowwaterfinitevolumemodels AT pspeixoto topographybasedlocalsphericalvoronoigridrefinementonclassicalandmoistshallowwaterfinitevolumemodels
_version_	1718426668243091456

Topography-based local spherical Voronoi grid refinement on classical and moist shallow-water finite-volume models

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