GEF4530 - CAM 5 source code and information

CAM 5.3 Source code overview

The full description of the Community Atmosphere Model CAM 5.3 can be found here.
CESM is a fully-coupled, community, global climate model that provides state-of-the-art computer simulations of the Earth's past, present, and future climate states.
Some facts about CESM:

Written in Fortran 90
About 900 000 lines of Fortran 90 code
About 12,000 lines of perl and shell scripts that configure, build, and run the model
Parallelized with MPI (Message Passing Interface) and OpenMP (Open Multi-Processing)
To keep track of code changes, CESM developers currently use subversion. However, some components use git.
Fortran Coding standard as well as style rules are enforced and anyone wishing to contribute to the Community Atmosphere Model must comply to these rules.

To browse and explore CAM5.3 source code, you can login on cruncher.
From a Linux terminal:


ssh -Y $LOGNAME@cruncher.norstore.uio.no

where $LOGNAME is your UIO username (replace it by your own username!)
Documentation on norStore facility can be found here.

Please note that these machines are not accessible outside the UIO networks. If you wish to login on abel or cruncher outside the UIO network, use X2Go Client.
The source code we will be using is stored in /projects/NS1000K/GEF4530/cesm1_2_2/models/atm/cam:


cd /projects/NS1000K/GEF4530/cesm1_2_2/models/atm/cam
ls

bld: scripts ro generate makefiles and dependencies for compiling CAM5
chem_proc: MOZART chemical preprocessor
doc: change log
src: source code for CAM5
test: CAM testing framework
tools: utility to generate or remap terrain dataset

The full developers guidelines can be found here.
The source code for CAM 5.3 is located in the "src" and its sub-directories (the main parts are highlighted in bold):

control: contains several Fortran 90 modules to control CAM 5. That's a good starting point to explore CAM source code. Look for instance at cam_comp.F90:
The main subroutines for controlling CAM 5 are:


        .
    .
    .
   implicit none
   private
   save
   !
   ! Public access methods
   !
   public cam_init      ! First phase of CAM initialization
   public cam_run1      ! CAM run method phase 1: Runs first phase of dynamics and first phase of physics (before surface model updates).
   public cam_run2      ! CAM run method phase 2: It requires the surface model updates.  And run the second phase of dynamics 
                        !                         that at least couple between physics to dynamics.
   public cam_run3      ! CAM run method phase 3: Third phase of the dynamics. For some dycores this will be the actual dynamics run, 
                        !                         for others the dynamics happens before physics in phase 1.
   public cam_run4      ! CAM run method phase 4: Final phase of atmosphere model run method. This consists
                        !                         of all the restart output, history writes, and other file output.
   public cam_final     ! CAM Finalization      :  CAM finalization.
 
    .
    .
    .

dynamics: source code for the different dynamical core options.
physics: model physics (for instance check physics/cam directory)
advection
chemistry
Interaction with other components: one of these components will be used to interact with other models (land, etc.). We do not discuss this part as we do not run a full coupled configuration.

cpl_esmf
cpl_mct
cpl_share

utils: Fortran 90 modules containing utilities (such as sorting methods, namelist utilities, PIO io interface, etc.)
unit_drivers: Parallel Offline Radiation Tool (PORT); not used for our configuration.