Downloading R-CESM

The R-CESM code is publicly available through our github repository . To simply download and use the model, no git knowledge is required other than what is documented in the following steps.

  1. Navigate to a suitable working directory, and clone the current stable tag of the R-CESM model source code

git clone https://github.com/ihesp/cesm.git -b ihesp-regional-master_200911 my_rcesm_sandbox

This will create a new directory my_rcesm_sandbox in your current working directory.

  1. Optionally, you can checkout the current unstable, developmental branch of R-CESM using

git clone https://github.com/ihesp/cesm.git -b ihesp-regional-master my_rcesm_sandbox

  1. Navigate into the source directory, and use the manage_externals/checkout_externals script to download the individual R-CESM components

./manage_externals/checkout_externals

The checkout_externals script is a package manager that pulls the appropriate versions of the CIME and active component (WRF, ROMS, CLM) source codes into your R-CESM working directory. The script reads the Externals.cfg configuration file to obtain the versions and repositories of the code that will be downloaded.

At this point you have a working version of R-CESM.

For general information on using the CIME framework in the context of CESM, see the CIME documentation at http://esmci.github.io/cime/ .

More details on checkout_externals

The file Externals.cfg in your top-level RCESM directory tells checkout_externals which tag/branch of CIME should be brought in to generate your sandbox. (This file serves the same purpose as SVN_EXTERNAL_DIRECTORIES when CESM was in a subversion repository.)

NOTE: Just like svn externals, checkout_externals will always attempt to make the working copy exactly match the externals description.

You need to rerun checkout_externals whenever Externals.cfg has changed (unless you have already manually updated the relevant external(s) to have the correct branch/tag checked out). Common times when this is needed are:

  • After checking out a new RCESM branch/tag

  • After merging some other RCESM branch/tag into your currently checked-out branch

checkout_externals must be run from the root of the source tree. For example, if you cloned RCESM with

git clone https://github.com/ihesp/rcesm1.git my_rcesm_sandbox

then you must run checkout_externals from /path/to/my_rcesm_sandbox.

To see more details of checkout_externals, issue

./manage_externals/checkout_externals --help