iModel

Icosahedral grid tools for geophysical fluid dynamics modelling

Pedro Peixoto Fev 2019 ([email protected])

With contributions from MSc/PhD students.

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iModel is a pack of tools to work with icosahedral and Voronoi geodesic grid based geophysical fluid models. Fully Fortran written, with outputs using GMT/Matlab/Python. It contains:

• Grid generator and grid tools, including grid optimization
• Locally refined grids, topography based (MSc L. Santos)
• Interpolation and vector reconstruction pack
• Multigrid solver (MSc M. Silva)
• Transport model (Semi-Lagrangian)
• High order finite volume transport model (PhD Bramatti)
• Finite Volume Shallow Water Model
• Finite Volume Moist Shallow Water Model (MSc L. Santos)

Additionally includes (Developed by John Thuburn):

• A spherical shallow water model version of ENDGame model, which uses finite differences on lat-long grid (endgame/)
• A spherical shallow water model of a mixed finite elements schemes, uses cubed shere or hexagonal grid (mfem_swm/)

Additionally includes (Developed by Pedro Peixoto)

• A planar shallow water model writen in Matlab using finite differences regular C-grid energy enstrophy conserving schemes (fdc_een_swm)

Please read doc/manual.pdf for further information and doc/ in submodel folders.

iModel:

• Runs on Linux (tested on Debian and Ubuntu)
• Fortran 90 (tested with ifort and gfortran)

1. Use the Makefile to compile (just type 'make')

2. Run using "./imodel". These will call the necessary routines for grid generation or modelling. Edit imodel.f90 for your purpuses.

3. Mesh parameters must be set in par/mesh.par or other par/*.par files Other parameters must be set in par/ directory

4. Choose the simulation to be run in mesh.par (1, 2...)

5. Output is written in data/

a) Use GMT visualization tool scripts from gmt/plot.sh to plot output (Generic Mapping Tool need to be installed separately) - depreceated b) Use Python scripts from pyscript folder for visualization.

7. Problems? Send an e-mail to [email protected]

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Main references for iModel (see www.ime.usp.br/~pedrosp for exact reference):

• Santos, Peixoto, 2021: Topography based local spherical Voronoi grid refinement on classical and moist shallow-water finite volume models (Geoscientific Model Development)

• Yonggang Yu; Ning Wang; Jacques Middlecoff; Pedro Peixoto; Mark Govett, 2020: Comparing Numerical Accuracy of Icosahedral A-grid and C-grid Schemes in Solving the Shallow-Water Model (Monthly Weather Review)

• Peixoto, Thuburn and Bell, 2018: Numerical instabilities of spherical shallow water models considering small equivalent depths ( Quarterly Journal of the Royal Meteorological Society)

• Bell, Peixoto, Thuburn, 2017: Numerical instabilities of vector invariant momentum equations on rectangular C-grids (Quart. J. Roy. Meteorol. Soc.)

• Peixoto, 2016: Accuracy analysis of mimetic finite volume operators on geodesic grids and a consistent alternative (Journal of Computational Physics)

• Peixoto, PS and Barros, SRM, 2014 : On vector field reconstructions for semi-Lagrangian transport methods on geodesic staggered grids (Journal of Computational Physics)

• Peixoto, PS and Barros, SRM, 2013 : Analysis of grid imprinting on geodesic spherical icosahedral grids (Journal of Computational Physics)