1.9.1. Creating an ESMF mesh file from a netCDF file

This page includes instructions for using the mesh_maker tool to create a mesh file from a netCDF file with valid 1D or 2D latitude and longitude coordinates. It also shows how to use mesh_plotter to visualize a mesh file.

Note

An ESMF mesh file is a netCDF file that includes the information about the grid’s coordinates and their connectivity to each other in an Unstructured Grid Format. Additional information about ESMF mesh files is available here.

You can check out the mesh_maker options like so:

> tools/site_and_regional/mesh_maker --help

|------------------------------------------------------------------|
|---------------------  Instructions  -----------------------------|
|------------------------------------------------------------------|
This script creates ESMF unstructured GRID (mesh file) from a netCDF
file with valid lats and lons. Provided lats and lons can be 1D or 2D.

For example for running WRF-CTSM cases, the user can create a mesh
file for their domain :
    ./mesh_maker.py --input wrfinput_d01 --output my_region
        --lat XLAT --lon XLONG --verbose

optional arguments:
  -h, --help        show this help message and exit
  --input INPUT     Netcdf input file for creating ESMF mesh.
  --output OUTPUT   Name of the ESMF mesh created.
  --outdir OUT_DIR  Output directory (only if name of output mesh is not
                    defined)
  --lat LAT_NAME    Name of latitude varibale on netCDF input file. If none
                    given, looks to find variables that include 'lat'.
  --lon LON_NAME    Name of latitude varibale on netCDF input file. If none
                    given, looks to find variables that include 'lon'.
  --mask MASK_NAME  Name of mask varibale on netCDF input file. If none given,
                    create a fake mask with values of 1.
  --area AREA_NAME  Name of area variable on netCDF input file. If none given,
                    ESMF calculates element areas automatically.
  --overwrite       If meshfile exists, overwrite the meshfile.
  -v, --verbose     Increase output verbosity

1.9.1.1. Example: Making and visualizing a mesh file

In this example, we will use mesh_maker to create a mesh file from a netCDF file with 2D latitudes and longitudes. On the sample input provided, those coordinates are saved on the LATIXY and LONGXY variables, respectively.

input_file="python/ctsm/test/testinputs/surfdata_5x5_amazon_hist_78pfts_CMIP6_2000_c230517.nc"
output_file="meshfile_5x5_amazon.nc"

# Create the file. (Add --verbose for additional debugging information.)
tools/site_and_regional/mesh_maker --input "${input_file}" --output "${output_file}" --lon LONGXY --lat LATIXY

# Visualize the meshes
tools/site_and_regional/mesh_plotter --input "${output_file}"

This produces two figures: