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DWD ICON Tools

The DWD ICON Tools contain a set of routines which may be suitable for reading, remapping and writing of fields from and to predefined grids, e.g., regular (lat-lon, gaussian) or triangular (ICON). It can be used to generate lateral boundary conditions (LBC) and initial conditions (IC) for ICON-LAM simulations.

Repository

In order to get access to the DWD ICON Tools repository hosted on the C2SM GitHub organisation , please contact your group's technical contact. They will be responsible for adding you to the appropriate user group.

Web Interface

Zonda uses DWD ICON Tools under the hood: icongridgen is used to generate ICON grids, and iconsub is used to create the lateral boundary grid. Zonda is publicly available at zonda.ethz.ch .

Usage

Säntis

On Säntis, DWD ICON Tools is provided via the climtools uenv:

uenv start climtools/25.2:v1 --view=climtools

The resulting binaries (iconremap, iconsub, icongridgen, icondelaunay, icongpi) are directly available within this uenv.

Euler

On Euler, DWD ICON Tools can also be built directly against Euler's native module software stack.

Clone the repository with submodules:

git clone --recurse-submodules git@github.com:C2SM/icontools.git
cd icontools

Load the required modules: 

module load stack/2025-06 gcc/12.2.0 openmpi/4.1.7
module load netcdf-c/4.9.2 netcdf-fortran/4.6.1 hdf5/1.14.5 eccodes/2.34.0 libaec/1.0.6 libpng/1.6.39

Configure and build on a compute node:

srun -c 8 --time=00:15:00 bash -c './do_configure.sh && make -j 8'

The resulting binaries (iconremap, iconsub, icongridgen, icondelaunay, icongpi) are placed in the icontools/ subdirectory.

Run

The folder C2SM in the icontools repository contains a bunch of scripts to run iconremap and icongridgen on Säntis. Most likely you will use the DWD ICON tools to generate a new grid or interpolate boundary conditions for limited-area ICON runs.

Below is a recipe to create initial and boundary files for an ICON-LAM run on Säntis.

Clone the repository

git clone git@github.com:C2SM/icontools.git

Generate a new ICON grid

icongridgen --nml icontools/C2SM/gridgen.nml

Interpolate BC from IFS

This manual refers to the workflow MeteoSwiss currently uses to run LAM simulations.

  • Add fields FI and z from IFS analysis to LBC prior to the interpolation using cdo (GRIB only).

    Note

    Ensure that cdo is available through uenv or has been installed.

    cdo -selname,FI analysis_file fi_file
cdo -selname,z analysis_file z_file
cdo settime,'03:00:00' fi_file fi_file_time
cdo settime,'03:00:00' z_file z_file_time
cdo setreftime,2019-09-30,03:00:00  z_file_time z_file_reftime
cat lbc_file zfile_reftime fi_file_time > complete_file

  • Adapt scripts icontools/C2SM/remap_ini and icontools/C2SM/remap_lbc to your needs

  • Remap IFS data for BC:

    sbatch -A <account> icontools/C2SM/remap_lbc

  • Remap IFS data for analysis:

    sbatch -A <account> icontools/C2SM/remap_ini

Documentation