Downloading GCHP

The GCHP source code is hosted at https://github.com/geoschem/GCHP. Clone the repository:

gcuser:~$ git clone https://github.com/geoschem/GCHP.git Code.GCHP

The GCHP repository has submodules (other repositories that are nested inside the GCHP repository) that aren’t automatically retrieved when you do git clone. To finish retrieving the GCHP source code, initialize and update the submodules:

gcuser:~$ cd Code.GCHP
gcuser:~/Code.GCHP$ git submodule update --init --recursive

By default, the source code will be on the main branch. Checking out an official release is recommended because they are scientifically-validated versions of the code, and it records the version for your future reference. You can find the list of GCHP releases here. Checkout the version that you want to work with, and update the submodules:

gcuser:~/Code.GCHP$ git checkout 13.3.4
gcuser:~/Code.GCHP$ git submodule update --init --recursive

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Before continuing, it is worth checking that the source code was retrieved correctly. Run git status to check that there are no differences:

gcuser:~/Code.GCHP$ git status
HEAD detached at 13.3.4
nothing to commit, working tree clean
gcuser:~/Code.GCHP$

The output of git status should say that you are at the right version and that there are no modifications (nothing to commit, and a clean working tree).