Sea-ice: how to update input dataset?
The ice fraction data (used for prescribed CICE) is found in the same data file that provide SST data to the data ocean model since SST and ice fraction data are derived from the same observational data sets and are consistent with each other.
Copy SST file to your case directory:
On Abel:
export EXPNAME=sea_ice
cd ~/cesm_case/f2000.T31T31.$EXPNAME
cp /work/users/$USER/inputdata/atm/cam/sst/sst_HadOIBl_bc_48x96_clim_c050526.nc .
To change sea-ice fraction surface boundary data, use nco utilities to edit values on the file.
We will use a function called ncap2 – (netCDF Arithmetic Averager) single line command below:
On Abel:
module load nco
ncap2 -O -s 'lat2d[lat,lon]=lat' -s 'omask=(lat2d >= 30.)' -s 'ice_cov=(ice_cov*(1-omask))' sst_HadOIBl_bc_48x96_clim_c050526.nc sst_HadOIBl_bc_48x96_clim_$EXPNAME.nc
Apply this change using env_run.xml (recommended over user_nl* since also present in
docn.streams.txt.prescribed):
- figure out which namelist variable to change:
grep sst_ *.xml
- Change it in env_run.xml
./xmlchange -file env_run.xml -i SSTICE_DATA_FILENAME -val ./sst_HadOIBl_bc_48x96_clim_sea_ice.nc
Process env_run.xml to make namelist changes effective (create namelist files)
./preview_namelists
Copy changed SST data file to run directory
cp sst_HadOIBl_bc_48x96_clim_sea_ice.nc /work/users/$USER/f2000.T31T31.$EXPNAME/run/.
Before submitting your experiment, make sure you adjust the wall clock time!
Now you are ready to submit your simulation:
On Abel:
cd ~/cesm_case/f2000.T31T31.$EXPNAME
./f2000.T31T31.$EXPNAME.submit
Once your short simulation is done, check the outputs: were your changes taken into account? Do you get significant results?
If you are happy with your short run, you can setup your long run (14 months) experiment.