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Extract the OpenIFS package

Create your local installation of OpenIFS 48R1.0 by cloning or branching from the git repository with the OpenIFS package. The location will be your new OIFS_HOME place. 

You will need approximately 4 GB of disk space for the model sources, the bundle packages, and the built model binaries. 

git clone ssh://git@git.ecmwf.int/~daha/openifs-main-git.git

Please note that currently access to this repository is restricted to a limited number of users.

 Build OpenIFS

The $OIFS_HOME/bin/openifs-test.sh script can be used to build the model and run initial tests. 

  • Edit the script and in line 16 set the location of your $OIFS_HOME directory which is the location where you have extracted the git repository and where this script should be located.
  • The usage of the script is shown with the command:  openifs-test.sh -h
  • The option -e defines the compiler environment (intel or gnu). The default is intel. 

Run the build process and the tests using the following command:

cd $OIFS_HOME
./bin/openifs-test.sh -cbt

Note: It is normal to see warnings during the build process.

This will build the model binaries for the selected compiler and will run the ifs-test t21 and t42 tests.

  Set up the platform configuration file

You will need to set up a configuration file for your OpenIFS installation.

  • This file can be located anywhere but the recommended location would be somewhere inside your $OIFS_HOME installation.
  • This file sets global variables for your model installation, depending on your local system, and it will need to be "sourced" prior to running the model.
  • We provide a template for this configuration file in $OIFS_HOME/bin/oifs48r1-config.sh. You should edit this file and update variable OIFS_HOME with your installation's path.

We recommend that you include the following command in your shell configuration file (e.g. .bashrc): 

source /path/to/configfile/oifs48r1-config.sh

This command should also be include in any batch job scripts that are intended to run OpenIFS.

 Set up a forecast experiment

Extract the example forecast experiment i4xc.tgz into a location suitable for model experiments. 

Note:  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. 

Example: 
On the ECMWF hpc2020 our model installation $OIFS_HOME will be in $HOME/openifs and for the experiment we extract the i4xc package in $PERM. The experiment directory shall therefore be $PERM/i4xc/2016092500. 

Ensure the namelist files for the atmospheric model (fort.4) and for the wave model (wam_namelist) are found in the experiment directory.

You will need to copy two 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.
  • config.h: this is configuration file that determines settings for your experiment. It will be read by oifs-run. 

Copy both files from $OIFS_HOME/bin into your experiment directory.

cp i4xc.tgz $PERM
cd $PERM
tar -xvzf i4xc.tgz
cd ./i4xc/2016092500
cp $OIFS_HOME/bin/oifs-run .
cp $OIFS_HOME/bin/config.h .

Determine experiment parameters

You should 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 i4xc can be run for up to 144 hours (6 days) by setting CSTOP='h144'.

You should edit the 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 config.h settings. 

Note:  If no 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 config.h file appropriately or provide the correct command line parameters.

The config.h file contains the following settings:

OIFS_EXPID="i4xc"       # 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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