Icosahedral grid tools for geophysical fluid dynamics modelling

Pedro Peixoto Oct 2017 ([email protected])

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. It contains:

• Grid generator and grid tools, including grid optimization
• Interpolation and vector reconstruction pack
• Multigrid solver
• Transport model (Semi-Lagrangian)
• Shallow water model

Also 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/)

Also 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.

• 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/

6. Use GMT visualization tool scripts from gmt/plot.sh to plot output (Generic Mapping Tool need to be installed separately)

7. Problems? Send me an e-mail

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

• Peixoto, Thuburn and Bell, 2017: 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)