Adding info about downloading and using SourceMods

models/POP/readme.rst

@@ -134,6 +134,13 @@ It is run by the setup scripts.
 |                     | where the restarts from the GDEX were downloaded/stored.  |
 +---------------------+-----------------------------------------------------------+
 
+One set of variables to make sure are set correctly in this script are related to
+the SourceMods enable POP to recompute the barotropic velocity to prevent the
+barotropic solver from crashing. You can find and download the SourceMods available
+for POP-DART `here <https://www.image.ucar.edu/pub/DART/CESM/>`_. Ensure that the
+environment variable use_SourceMods is set to TRUE and the environment variable
+SourceModDir matches the directory path where the SourceMods were downloaded/stored.
+
 Setup scripts
 ~~~~~~~~~~~~~