Adding your own runoff product to the CESM (Advanced)

Adding your own runoff product to the CESM (Advanced)#

To add your own runoff product to the CESM, you need three things. A Stream Definition File, an ESMF Mesh file, and the dimensions of your raw data.

ESMF Mesh File#

An ESMF Mesh File can be created like below, using CrocoDash Grids.

from CrocoDash.grid import Grid
from CrocoDash.topo import Topo
import xarray as xr

grid = Grid(
    lenx=360,
    leny       = 150,         # grid length in y direction
    cyclic_x=True   ,    
    ystart     = -60,       # start/end 10 degrees above/below poles to avoid singularity
    resolution = 0.10,
    name = "GLOFAS",
)
topo = Topo(grid, min_depth = 0)
topo.set_flat(10)
topo.write_esmf_mesh("<path>")

Stream Definition File#

In your case directory, copy the following file and name it drof.streams.xml:

<?xml version="1.0"?>
<file id="stream" version="2.0">

  <stream_info name="rof.<PRODUCT_NAME>">
    <taxmode>cycle</taxmode>
    <tintalgo>upper</tintalgo>
    <readmode>single</readmode>
    <mapalgo>bilinear</mapalgo>
    <dtlimit>3.0</dtlimit>
    <year_first>"START_YEAR"</year_first>
    <year_last>"END_YEAR"</year_last>
    <year_align>"START_YEAR"</year_align>
    <vectors>null</vectors>
    <meshfile>"PATH_TO_THE_PREVIOUSLY_GENERATED_ESMF_MESH_FILE"</meshfile>
    <lev_dimname>null</lev_dimname>
    <datafiles>
      <file>"PATH_TO_RAW_DATA_FILE_IN_NETCDF3_64BIT_OFFSET"</file>
    </datafiles>
    <datavars>
      <var>"NETCDF_VARIABLE_NAME_IN_FILE" Forr_rofl</var>
    </datavars>
    <offset>0</offset>
  </stream_info>

</file>

Additional Notes#

  1. Update the CESM components/cdeps/drof directory.
    The following entry should already exist in namelist_definition_drof.xml:

<value drof_mode="<PRODUCT_NAME>">rof.<PRODUCT_NAME></value>

  1. Update config_component with the new <PRODUCT_NAME>:

<desc rof="DROF[%NULL][%NYF][%<PRODUCT_NAME>]...">

Make sure to replace placeholders (<PRODUCT_NAME>, START_YEAR, END_YEAR, file paths, and variable names) with your actual values.

Add the dimensions#

Make the following xml changes in your case directory:

./xmlchange ROF_NY=1500

./xmlchange ROF_NX=3600

./xmlchange ROF_DOMAIN_MESH=<MESH PATH>

There may be a few additional changes in the CESM, but this covers a majority of them.

Then, you can add the mapping files generated through CrocoDash to your case (which requires a passed in ESMF mesh file)

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