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Info

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). 

  • All model sources, data files and configuration scripts that are required for the worked example experiment described in this guide can be found on the ECMWF file system web site here: https:  /perm//sites.ecmwf.int/openifs/oifs_data/48r1/exampleopenifs-data/ (only registered OpenIFS users will be given access)
  • For users without with access to the ECMWF HPC facility we provide URLs for downloading all required data files and configuration scripts.an internal filepath location for the data packages (without the model source code). 
  • In our example the The model will be installed into $HOME/openifs-48r1/ as a default location.1/
  • The example forecast experiment will be set up in directory $OIFS_EXPT/ab2a/

It is important to note that the installation process on hpc2020 will not directly translate to alternative systems. To address this we present details about a docker install in the last section of this guide.

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Create your local installation of OpenIFS 48R1.1 48r1 by downloading and extracting the tarball containing the model source package.

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In the example below we assume that the OpenIFS model shall be installed in the user's HOME directory, and that the wget utility is available for convenient download: 

Code Block
languagebash
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cd $HOME
wget https://sites.ecmwf.int/openifs/openifs-data/src/48r1/# download the openifs-48r1.tar.gz model package and copy the tarball to your home directory:
cp openifs-48r1.tar.gz $HOME
tar -xvzf openifs-48r1.tar.gz

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Code Block
languagebash
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export OIFS_HOME=$HOME/openifs-48r1.1/

The other model environment variables are

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Note

If you do not have access to the ECMWF hpc2020 file system, or if you wish to install the climatological input files in a local directory of your choice, then you can download the required data from this site: https://sites.ecmwf.int/openifs/openifs-data/ifsdata/48r1/

As a minimum you will require the packages ifsdata_rtables_48r1.tgz,  and ifsdata_climatology_48r1.tgz, and the files required . You will also need to download the package for your selected horizontal grid resolution, which in the case of our worked example on this page is for a T255 grid, and therefore you will at the very least need the package ifsdata_48r1_climate.v020_255.tgz. Installing the packages for all supported horizontal grids will require a lot of disk space and is therefore not recommended.

Download and extract the files in these tarballs into the same directory in your chosen location, and the filepath of this directory should then be set to variable OIFS_DATA_DIR. 

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Code Block
languagebash
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source /path/to/file/location/oifs-config.edit_me.sh
# using our installation example:
# source $HOME/openifs-48r1.1/oifs-config.edit_me.sh

We recommend to include this command in your Linux shell startup configuration (e.g. in .bashrc). 

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Info

$OIFS_HOME/oifs-config.edit_me.sh also contains a environment variables that relate to the Single-Column Model (SCM). These are discussed in OpenIFS 48r1 - Getting started with the SCM. 

 Build OpenIFS

In this section we describe how the model binary executable (and other helper programs) will be built.

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  • 21 3-D OpenIFS forecast-only tests with and without chemistry
  • 1 SCM test (based on TWP-ICE)

-j is an optional argument that allows the user to define the number of threads used to create and build openifs, e.g.

Code Block
languagebash
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$OIFS_TEST/openifs-test.sh -cbt -j 16

which will perform the create and build step using 16 threads

  • If -j is not supplied as a command line argument, as in the above argument, the number of threads will default to the IFS build options for 48r1, i.e. 
    • 64 threads for ATOS
    • 8 threads for all other systems
  • If -j argument is present, then the command line number of threads takes precedence over the defaults for any system 
    • The default of 8 threads can be increased for larger systems. Such an increase may speed up the build. For advice on this please liaise with the system administrator.
    • It is important to note that 8 threads can be problematic for older and lower spec systems. For example, it will not work with a 4 core intel m3. In this case reduce the number of threads to 2 for example. 
Info

In addition to the command line options defined above (-cbt) , openifs-test.sh invokes some default ecbuild options and allows a user to add ecbuild options from command line using the -- notation, e.g., $OIFS_TEST/openifs-test.sh -cbt --without-single-precision. Openifs-test - build options describes some of these options.

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This page has shown you how to download, extract, build and test the OpenIFS 3D global model on your local computing system. The next step will be to carry out a first global forecast experiment model run for which we have prepared an example case study experiment. To do this please continue on the page page Setting up and running a forecast experiment.