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create_newcase

create_newcase#

The tool that generates a new case is create_newcase. Note that in the CESM jargon, a case is equivalent to a simulation.

The create_newcase command is located in $CESMROOT/cime/scripts

You can go to that directory using the command:

cd $CESMROOT/cime/scripts

Figure 1 shows the location of the command create newcase within the CESM code.

create_newcase

Figure 1: CESM structure and the create_newcase command

Syntax of create_newcase#

The create_newcase command has three required inputs (and other optional inputs).

The required inputs are

  • case: the name and directory path of your case e.g., setting case to ~/cases/case01 will make a simulation called case01 and it will be located in ~/cases

  • compset: the CESM component set that you’d like to use. The CESM2 components can be combined in numerous ways to carry out various scientific experiments. A particular mix of components, along with component-specific configuration and/or namelist settings is called a component set or compset. See https://docs.cesm.ucar.edu/models/cesm2/config/compsets.html for a list of pre-defined compsets.
    Note that here we will be using the compset B1850-tutorial which has been specially developed for the purposes of this tutorial - it is not available within the CESM2 release.

  • res: the resolution that you’d like to use.

In our example, the create_newcase command will be:

./create_newcase --case ~/cases/case01 --compset B1850-tutorial --res f19_g17

The syntax for the create_newcase command is also illustrated in Figure 2 below.

create_newcase

Figure 2: Syntax for the create_newcase command

Result of create_newcase#

The create_newcase command will create the case directory and the build/run directories. The case directory will contain the scripts you need for the following steps: case.setup, case.build and case.submit. This is illustrated in Figure 3 below:

create_newcase

Figure 3: View of the CESM directory structure after the create_newcase command

More advanced information:#

You are not restricted to the pre-defined compsets. You can create your own. Visit: https://esmci.github.io/cime/versions/master/html/users_guide/compsets.html for documentation on how to create your own.

In addition to the CESM web pages, you can find information on available compsets and resolutions using the query_config tool located in $CESMROOT/cime/scripts e.g.,

cd $CESMROOT/cime/scripts 
./query_config --help

will provide you with information on the arguments taken by query config and then e.g.,

./query_config --grids

will list all the available grids.

./query_config --compsets

will list all the available component sets.

You can use this tool to find the arguments you want to provide to create_newcase.

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