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This prints (among other things):

    ncol = 60482 ;

You will need this value for several of the following steps.

Create ESMF mesh file from SCRIP file

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In the directory with your SCRIP file ($REPO/grids), run (be sure all on one line):

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Modify the bold text to point to your SCRIP file, grid name, etc.

Can add option --output_data_directory to specify location of final topography file (be sure it already exists).

This can take several hours.   (to do: set up to run as a submitted job with qsub)

Generate CTSM (CLM) surface datasets

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> git clone https://github.com/ESCOMP/CESM.git cesm3_0_beta01
> cd cesm3_0_beta01
> git checkout cesm3_0_beta01
> ./bin/git-fleximod update

Below, <cesm> $CESMCODE refers to yourcesm3_0_beta01 directory.

CCS_CONFIG

1. Add an entry for your new ESMF mesh file in <cesm>/ccs_config/component_grids_nuopc.xml

For this grid:

  <domain name="(grid_name)ne0np4.Nanjing.ne30x8">
    <nx>(ncol)<    <nx>60482</nx> <ny>1</ny>

    <mesh>/your_path/(new_grid)_ESMFmesh.nc</mesh>

    <desc>(new_grid)     <mesh>/glade/work/emmons/tutorial_Nanjing/ne0np4.Nanjing.ne30x8/grids/Nanjing_ne30x8_np4_MESH.nc</mesh>
    <desc>ne0np4.Nanjing.ne30x8 is a Spectral Elem 1-deg grid with a 1/NN 8 deg refined region over …east China:</desc>
    <support>Test     <support>Test support only</support>
  <  </domain>Include the corresponding number of grid columns in the <nx> argument, and a proper <domain_name>.

2. Add a grid alias entry in <cesm>/ccs_config/modelgrid_aliases_nuopc.xml:

  <model_grid alias="ne0ARCTICne30x4ne0Nanjingne30x8_ne0ARCTICne30x4ne0Nanjingne30x8_mt13mt12" not_compset="_POP">
    <grid name="atm">ne0np4.ARCTICNanjing.ne30x4<ne30x8</grid>
    <grid name="lnd">ne0np4.ARCTICNanjing.ne30x4<ne30x8</grid>
    <grid name="ocnice">ne0np4.ARCTICNanjing.ne30x4<ne30x8</grid>
    <mask>tx0.1v3</mask>
  </model_grid>

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Set up a CAM case for testing new grid

Create a new case with FHIST compset:

> <cesm>/cime/scripts/create_newcase ...

> cd <case_dir>

> ./xmlchange NTASKS= ___

> ./case.setup

Add to user_nl_cam:

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On derecho, go to the directory (or create one) for all your CESM cases (in your /glade/u/home/$USER or /glade/work/$USER directory). Create a new case with FHIST compset:

> /glade/work/emmons/cesm_src_derecho/cesm3_0_beta01/cime/scripts/create_newcase --case /glade/work/emmons/tutorial_Nanjing/cases/f.e3beta01.FHIST.Nanjing_ne30x8.01 --res ne0Nanjingne30x8_ne0Nanjingne30x8_mt12 --compset FHIST --run-unsupported --project AACD0004 --pecount 2048

This creates a new directory, $CASEROOT = /glade/work/emmons/tutorial_Nanjing/cases/f.e3beta01.FHIST.Nanjing_ne30x8.01.

> cd $CASEROOT
> ./case.setup

Add to user_nl_cam:

 ncdata = '/glade/work/emmons/tutorial_Nanjing/ne0np4.Nanjing.ne30x8/cami-mam4_0000-01-01_ne0np4.Nanjing.ne30x8_L32_c240809.nc'
 bnd_topo = '/glade/work/emmons/tutorial_Nanjing/ne0np4.Nanjing.ne30x8/topo/topo/Nanjing_ne30x8_gmted2010_modis_bedmachine_nc3000_Laplace0100_noleak_20240729.nc'
 drydep_srf_file = '/glade/work/emmons/tutorial_Nanjing/ne0np4.Nanjing.ne30x8/atmsrf/atmsrf_ne0np4.Nanjing.ne30x8_240809.nc'
 se_refined_mesh = .true.

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 se_mesh_file =

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'/glade/work/emmons/tutorial_Nanjing/ne0np4.Nanjing.ne30x8/grids/Nanjing_ne30x8_EXODUS.nc'

 inithist = 'DAILY'

Set the timestep based on recommended value in: https://github.com/ESMCI/Community_Mesh_Generation_Toolkit/blob/master/VRM_tools/Docs/CAM-tsteps-inic-for-newgrids_v0.pdf

./xmlchangeATM_NCPL=XXX384

Add to user_nl_clm

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nl_clm

fsurdat = '/glade/work/emmons/tutorial_Nanjing/ne0np4.Nanjing.ne30x8/land/surfdata_Nanjing_ne30x8_SSP3-7.0_1979_78pfts_c240809.nc'
flanduse_timeseries = '/glade/work/emmons/tutorial_Nanjing/ne0np4.Nanjing.ne30x8/land/landuse.timeseries_Nanjing_ne30x8_SSP3-7.0_1979-2026_78pfts_c240809.nc'

Add the override flag in your individual case directory to ensure CTSM doesn’t error out due to an unsupported grid:

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If it does not run, try adjusting parameters, as described in https://github.com/ESMCI/Community_Mesh_Generation_Toolkit/blob/master/VRM_tools/Docs/CAM-tsteps-inic-for-newgrids_v0.pdf 

Once it runs, change runs, change the frequency of writing IC files from daily to monthly (in user_nl_cam: inithist = 'MONTHLY') and  run a year.  Save the final *cam.i.* file to use for future CAM simulations (ncdata in user_nl_cam). 

Also, save Save the final CLM restart file (*.clm2.r.*.nc) to use for finidat in user_nl_clm in future runs.

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You will need to regrid a previous CAM-chem IC file to your grid (to use for ncdata in user_nl_cam).  If you have an IC file on a Finite Volume grid (f09) use 'interpic' as shown above.  If starting from a file on ne30 grid, use the ncl script at: https://github.com/NCAR/IPT/tree/master/Initial_conditions

Also, regrid emissions and met files to your grid.

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