2 Running the Coupler

The Coupler cannot run by itself, it can only execute in the context of running
the complete CCSM system -- a framework that requires atmosphere, ice, land, and
ocean components.  The scripts that build and run the CCSM system are described
in detail in the CCSM 2.0 User's Guide, a holistic guide to running the complete
system.  This Guide includes a line-by-line explanation of the master run script
and the Coupler's "setup script".  A brief description of CCSM run scripts is 
below.  See the CCSM User's Guide for complete information.

2.1 Master Run Script and Coupler Setup Script

Two levels of c-shell scripts are used to build and run the CCSM system, which
of course, includes the Coupler.  A master "run script" coordinates the building
and running the complete system while the component model "setup scripts" are 
responsible for configuring each individual CCSM component (including the 
Coupler). The CCSM execution is controlled by the master script, referred to as
"the run script".  The run script has the following tasks:

   a. Set batch system options
   b. Define common build and run environment variables
   c. Select multi-processing and resolution specs
   d. Run the setup script for each component
   e. Run the CCSM Integration.
   f. Archive/harvest/resubmit when this run is finished

The common build and run environment variable defined in the run script are 
automatically propagated to each of the component model setup scripts. These 
variables define such things as the machine architecture, the number of CPUs to
run on, common experiment and file naming conventions.

Once the master run script has defined the common environment, each of the 
component models (cpl, atm, ice, lnd, and ocn) are configured using individual
component setup scripts (e.g. cpl.setup.csh) which:

   a. Parse the environment variables sent from the master run script. These 
      are, in effect, input variables that might be required by a setup script
      or otherwise might alter the behavior of the setup script.
   b. Position or create any input data files, as necessary, including input 
      namelist data files and mapping data files.
   c. Build the component executable.

Finally, when all of the component model setup scripts have successfully 
completed, the run script executes all CCSM components simultaneously.  The 
CCSM component models run simultaneously as a Multi-Program/Multi-Data (MPMD) 
message passing system, using MPI to exchange data.