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Worked Example: We explain the model installation and the process of running of a forecast experiment on the ECMWF Atos Sequana XH2000 HPC facility (hpc2020).
It is important to note that the installation process on hpc2020 will not directly translate to alternative systems |
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An example forecast experiment has been prepared for OpenIFS 48r1. The experiment ID is i4xc ab2a.
Extract the example forecast experiment i4xcab2a.tgz into a folder in a location suitable for model experiments. This folder will be your experiment directory.
Example:
On the ECMWF hpc2020 our model installation $OIFS_HOME will be in $HOME/openifs-48r1.1 and for the experiment we extract the i4xc package ab2a package to $PERM. The experiment directory shall therefore be $PERM $PERM/i4xcab2a/2016092500.
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cp /perm/openifs/oifs_data/48r1/example/i4xcab2a.tgz $PERM cd $PERM tar -xvzf i4xcab2a.tgz |
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The experiment directory would ideally be in a different location from the earlier model installation path $OIFS_HOME. In general, you will need more disk space for experiments, depending on the model grid resolution, the duration of the forecast experiment and the output fequency of model results. |
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cd $PERM/i4xcab2a/2016092500 cp ./ecmwf/fort.4 . cp ./ecmwf/wam_namelist . |
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cd $PERM/i4xcab2a/2016092500 cp $OIFS_HOME/scripts/oifs-run . cp $OIFS_HOME/scripts/exp-config.h . cp $OIFS_HOME/scripts/run.ecmwf-hpc2020.job . |
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- You can edit the atmospheric model namelist file fort.4. It contains Fortran namelists which control model settings and switches.
- An important switch to edit is in namelist NAMRIP the variable CSTOP. Set this to the desired length of the forecast experiment.
- Experiment
i4xccan ab2a can be run for up to 144 hours (6 days) by settingCSTOP='h144'.
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OIFS_EXPID="i4xcab2a" # your experiment ID OIFS_NPROC=8 # the number of MPI tasks OIFS_NTHREAD=4 # the number of OpenMP threads OIFS_GRIDTYPE="l" # the grid type, either 'l' for linear reduced grid, or 'o' for the cubic octahedral grid OIFS_RES="255" # the spectral grid resolution OIFS_NAMELIST='fort.4' # the name of the atmospheric namelist file (the default is fort.4, so this line could be omitted) OIFS_EXE="${OIFS_HOME}/build/bin/ifsMASTER.DP" # the name and location of the model binary executable OIFS_PPROC=true # enable postprocessing of model output after the model run OUTPUT_ROOT=$(pwd) # folder where pproc output is created (only used if OIFS_PPROC=true). In this case an output folder is created in the experiment directory. LFORCE=false # overwrite existing symbolic links in the experiment directory LAUNCH="" # the platform specific run command for the MPI environment (e.g. "mpirun", "srun", etc). |
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# run as batch job: cd $PERM/i4xcab2a/2016092500 sbatch ./run.ecmwf-hpc2020.job |
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The oifs-run script will in this case use its default launch parameters: srun -c${OIFS_NPROC} --mem=64GB --time=60 which will work fine with OIFS_NPROC=8 for experiment i4xcab2a.
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# run interactively: cd $PERM/i4xcab2a/2016092500 ./oifs-run |
Postprocessing
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- This data processing may take a couple of minutes to complete.
- Occasionally the message "ERROR: input file does not exist!" may occur which can be safely ignored. This happens when the script attempts to convert model output which was not generated by OpenIFS. The script will not fail but simply carry on looking for the next file.
- After successful completing the conversion process "Done." should appear on the terminal.
- As a result of this processing, regular gridded and compressed GRIB files are generated in
$PERM/mv/data/i4xcab2awhich can be visualised with by running the enclosed Jupyter Notebooksingle.ipynb
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