98 lines
4.1 KiB
Markdown
98 lines
4.1 KiB
Markdown
# Creating an ESMF mesh file from a netCDF file
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This gist includes instructions for creating and visualizing a mesh file from a netcdf file with valid 1D or 2D lats and lons coordinates.
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* **ESMF Mesh file** aka **Unstructured Grid File Format** is a netcdf file (format) that includes the information about the grids coordinates and their connectivity to each other.
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Additional information about ESMF mesh files are available [here](https://earthsystemmodeling.org/docs/release/ESMF_8_0_1/ESMF_refdoc/node3.html#SECTION03028200000000000000).
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------
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In this example, we will use `./mesh_maker.py` which uses `mesh_type.py` to create a mesh file and visualize it.
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1- First clone my fork and branch that includes these capabilities:
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``` Shell
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git clone https://github.com/negin513/ctsm.git ctsm_mesh
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cd ctsm_mesh
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git checkout subset_mesh_dask
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```
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2- Next run mesh_maker.py for a netcdf file:
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```
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cd tools/site_and_regional
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```
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Check all the avaialble options:
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```
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./mesh_maker.py --help
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```
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The output shows all available options for this script:
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```
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|------------------------------------------------------------------|
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|--------------------- Instructions -----------------------------|
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|------------------------------------------------------------------|
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This script creates ESMF unstructured GRID (mesh file) from a netcdf
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file with valid lats and lons. Provided lats and lons can be 1D or 2D.
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For example for running WRF-CTSM cases, the user can create a mesh
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file for their domain :
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./mesh_maker.py --input wrfinput_d01 --output my_region
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--lat XLAT --lon XLONG --verbose
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optional arguments:
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-h, --help show this help message and exit
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--input INPUT Netcdf input file for creating ESMF mesh.
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--output OUTPUT Name of the ESMF mesh created.
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--outdir OUT_DIR Output directory (only if name of output mesh is not
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defined)
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--lat LAT_NAME Name of latitude varibale on netcdf input file. If none
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given, looks to find variables that include 'lat'.
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--lon LON_NAME Name of latitude varibale on netcdf input file. If none
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given, looks to find variables that include 'lon'.
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--mask MASK_NAME Name of mask varibale on netcdf input file. If none given,
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create a fake mask with values of 1.
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--area AREA_NAME Name of area variable on netcdf input file. If none given,
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ESMF calculates element areas automatically.
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--overwrite If meshfile exists, overwrite the meshfile.
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-v, --verbose Increase output verbosity
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```
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Let's create a mesh file from a netcdf file with 1D lats and lons. On the sample files provided 1D lat and long coordinates are saved on `lsmlat` and `lsmlon` variables.
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```
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./mesh_maker.py --input /glade/scratch/negins/example_files/surfdata_4x5_hist_78pfts_CMIP6_simyr1850_275.0-330.0_-40-15_c220705.nc --output test_mesh_1d.nc --lat lsmlat --lon lsmlon --overwrite
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```
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`--verbose` option also provide additional information for debugging.
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This script will create regional and global mesh plots. For example for the above files, the plos are:
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test_mesh_1d_regional.png
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test_mesh_1d_global.png
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------
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## Creating Mesh files for a WRF domain:
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For running WRF-CTSM cases, we need to create ESMF mesh files for the WRF domain. We can create mesh file from wrfinput (wrf initial condition files). wrfinput has 2D coordinate information on `XLAT` and `XLONG` variable.
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For example, let's create a mesh file from a WRF input file for WRF-CTSM run.
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```
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./mesh_maker.py --input /glade/scratch/negins/example_files/wrfinput_d01 --output test_mesh_wrf.nc --lat XLAT --lon XLONG --overwrite
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```
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This produce mesh files for running for our WRF domain.
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Here is how the regional plot looks like for this mesh file:
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