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Set up a forecast experiment
An example forecast experiment has been prepared for OpenIFS 48r1. The experiment ID is ab2a.
Extract the example forecast experiment ab2a.tar.gz
into a folder in a location suitable for model experiments. The global OpenIFS configuration file (oifs-config.edit_me.sh
) sets the variable OIFS_EXPT
which should point to the root directory for your OpenIFS experiments. You should extract ab2a.tar.gz
to this location, and this folder will become your experiment directory.
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The experiment directory would ideally be in a different location from the earlier model installation path |
Example:
On the ECMWF hpc2020 our model has been previously installed to $OIFS_HOME
which is in $HOME/openifs-48r1.1
. For the experiment we extract the ab2a package to $OIFS_EXPT
which is in a different location on the file system. The experiment directory shall therefore be $OIFS_EXPT/ab2a/2016092500
.
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cd $OIFS_EXPT
wget https://sites.ecmwf.int/openifs/openifs-data/case_studies/48r1/karl/ab2a.tar.gz
tar -xvzf ab2a.tar.gz |
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You will need to copy three further scripts from the OpenIFS package into your experiment directory:
oifs-run:
this is a generic run script which executes the binary model program file.exp-config.h:
this is the experiment configuration file that determines settings for your experiment. It will be read by oifs-run.run
.ecmwf-hpc2020.job:
this is the wrapper script to submit non-interactive jobs on hpc2020
Copy these files from $OIFS_HOME/scripts
into your experiment directory.
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Determine experiment parameters
Namelist:
- 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 ab2a can be run for up to 144 hours (6 days) by setting
CSTOP='h144'
.
Experiment configuration file:
- You can edit the exp-config.h file which determines settings for this experiment.
- The oifs-run script will read the settings from this file.
- Alternatively, the settings can be passed to the oifs-run script via command line parameters, which takes precedence over the exp-config.h settings.
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You should always set up an exp-config.h for each experiment. If no exp-config.h file is found in the experiment directory, and if also no command line parameters are provided when calling oifs-run, then oifs-run will revert to its own default values which are not appropriate. In any case you should either edit the exp-config.h file appropriately or provide the correct command line parameters. |
The exp-config.h file contains the following settings:
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title | exp-config.h |
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Once you have made the appropriate changes to run.ecmwf-hpc2020.job
, you can submit it and, hence, run the experiment with the following commands
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# run as batch job:
cd $OIFS_EXPT/ab2a/2016092500
sbatch ./run.ecmwf-hpc2020.job |
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The job wrapper script will read the exp-config.h file and adopt the selected values. The exceptions are LAUNCH, which is set to "srun" for batch jobs, and OIFS_NPROC & OIFS_NTHREAD for which values from the batch job headers are used. The job wrapper script modifies the exp-config.h file accordingly prior to calling the oifs-run script. |
Running interactively
On the ECMWF hpc2020, running the model script interactively should be fine for lower grid resolutions up to T255L91.
- In order to run the experiment interactively, execute the oifs-run script from the command line in your terminal.
- If no command line parameters are provided with the oifs-run command, then the values from the exp-config.h will be used.
- In exp-config.h set OIFS_NPROC=8 and OIFS_NTHREAD to 4.
- In exp-config.h the LAUNCH variable should remain empty, i.e. LAUNCH="" and no --runcmd parameter should be provided in the command line.
The oifs-run script will in this case use its default launch parameters: srun -c${OIFS_NPROC} --mem=64GB --time=60
which will work fine with OIFS_NPROC=8 for experiment ab2a.
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# run interactively:
cd $OIFS_EXPT/ab2a/2016092500
./oifs-run |
Postprocessing
If in the exp-config.h file the OIFS_PPROC
variable has been set to true
(or if the --pproc command line parameter was used) then the model output in the experiment directory is further processed after completing the model run.
- In this case the script will generate a folder called
output_YYYMMDD_HHMMSS
, with YYYYMMDD being the current date and HHMMSS the current time. - This avoids accidental modification or overwriting of any previous results when the model experiment is repeated.
- For convenience a symbolic link
output
is set to the most recently generated model output. If the model run is repeated and a newoutput_YYYMMDD_HHMMSS
folder is generated, the symbolic link will be updated to point to the most recent output folder. - The variable
OUTPUT_ROOT
in exp-config.h determines where this ouput folder will be created. The default location is inside the experiment directory, but when assigning another path toOUTPUT_ROOT
this could be created elsewhere.
The postprocessing groups all model output fields and diagnostics into individual GRIB files with ascending forecast time step. Also, a copy of the atmospheric model namelist file fort.4, as well as the ifs.stat and NODE.01_001 log files are moved into the output folder.
This postprocessing is required if the Metview Python script is to be used later to visualise the model output.
Plotting of model output
Here we describe in a brief summary how plots from the model results can be generated. This permits a first-order sanity check whether the model results look sensible.
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