


Generally, the straigth forward procedure of generating branch and
hybrid runs, starting from an existing NorESM run, is described in
chapter 9 of the CCSM documentation: 

http://www.ccsm.ucar.edu/models/ccsm4.0/ccsm_doc/book1.html

The procedure should be the same for NorESM and CCSM.

Example:

Assume you want to do a branch run with name CASEBR, starting from the
date 0090-01-01 of the case CASE1 that has been run by USR1: 

1) Build a new case directory with the the same create_newcase command as used
   to build case $CASB1
>  create_newcase $HOME/noresm/cases/$CASBR .........

>  cd $HOME/noresm/cases/$CASBR

2) Change the file env_conf.xml (using xmlchange) to give a branch run
   starting from the correct dataset at the correct date:

>  xmlchange -file env_conf.xml -id RUN_TYPE    -val branch
>  xmlchange -file env_conf.xml -id RUN_REFCASE -val $CASE1
>  xmlchange -file env_conf.xml -id RUN_REFDATE -val 0090-01-01

2b) If you want to change the startdate e.g for a historic run you must use hybrid run set-up

>  xmlchange -file env_conf.xml -id RUN_TYPE    -val hybrid
>  xmlchange -file env_conf.xml -id RUN_REFCASE -val $CASE1
>  xmlchange -file env_conf.xml -id RUN_STARTDATE -val 1850-01-01
The startdate refers to the starting point of your new run
>  xmlchange -file env_conf.xml -id RUN_REFDATE -val 0090-01-01 

3) Configure and build the case

>  configure -case 
>  $CASEBR.$MACH.build

# If necessary, edit the Buildconf/$component.buildnml.csh files to
#  included changes done in $CASE1.

4) Prestage the necessary restart/initial data in $RUNROOT (default is
   /work/$LOGNAME/noresm/$CASEBR/run in NorESM on hexagon). We assumes
   that $USR1 has the data stored in /work/$USR1/archive/$CASEBR

> cd $RUNDIR
> cp /work/$URS1/archive/$CASE1/rest/0090-01-01-00000/* .

5) Start a 2 month test run 
> cd $HOME/noresm/cases/$CASBR
> xmlchange -file env_run.xml -id STOP_OPTION -val nmonths
> xmlchange -file env_run.xml -id STOP_N -val 2
> qsub $CASEBR.$MACH.run

