Supergrid

About

The supergrid is created using ORCA_gridgen which relies on the NEMO ocean modelling framework to generate tripolar grids for MOM6. For a complete description of the code, please check this user guide. The original code has been modified to create an supergrid (ocean_hgrid.nc), in addition to the defaults files for NEMO (coordinates.nc and coordinates_north.nc).

TODO: describe what else was modified… parallel, u point at the Equator, etc

Usage

File param.f90 has the modifications needed to generate the nominal 2/3 degree resolution grid (tx2_3); The original (default) configuration used for ORCA1 is also included for comparison (file param.f90.ori and trop.f90.ori). A simple diff of the files can be used to check what has been changed to create tx2_3:

diff param.f90 param.f90.ori

The code is intended to compile under any compliant Fortran 90 compiler. It must be compiled with a flag that promotes reals to 8 bytes. It must be linked with the NetCDF F90 library. To compile ORCA_gridgen on Casper, load the following modules:

module load intel/19.1.1
module load netcdf/4.8.1

Then type:

cd ORCA_gridgen
make clean
make

This should create an executable called “tripole.exe”. Next, type the following:

./tripole.exe

This should create three NetCDF files: ocean_hgrid.nc, coordinates.nc and coordinates_north.nc. For MOM6, we only use ocean_hgrid.nc.