The domain file in ESM

In order to set up a MPAS mesh-based MOSART/ELM simulation, I need to prepare a domain file.

After some effort, I was not able to find any documentation describing the so-called domain file.

However, I found quite some documentation on how to generate this domain file, such as: https://www2.cesm.ucar.edu/models/cesm1.2/clm/models/lnd/clm/doc/UsersGuide/x11812.html

Without looking at the official documentation, the only way to understand the structure of the domain file is through existing files and possibly code.

In general, the domain file stores the information of mesh cells, including cell center, vertices, and area.

The cell center is either a 1D (unstructured) or 2D (structured) array.

As a result, the vertices can be a 2D or 3D (structured) array. In practice, the vertices array often uses the (nj, ni, nv) structures to store the data.

For unstructured mesh, we can set nj or ni as 1.

Different types of domain files

ELM surface data

gen_domain to create a domain file for datm from a mapping file. The domain file is then used by BOTH DATM AND CLM to define the grid and land-mask.

Stream file

Differences between global and local domain files

ATM_DOMAIN_FILE and ATM_DOMAIN_PATH

    <entry id="ATM_DOMAIN_FILE">
      <type>char</type>
      <default_value>UNSET</default_value>
      <group>run_domain</group>
      <file>env_run.xml</file>
      <desc>atm domain file</desc>
    </entry>
    
    <entry id="ATM_DOMAIN_PATH">
      <type>char</type>
      <default_value>$DIN_LOC_ROOT/share/domains</default_value>
      <group>run_domain</group>
      <file>env_run.xml</file>
      <desc>path of atm domain file</desc>
    </entry>