add docuentation to setup experiment with levante

README.md

 # Catalog for Pamtra insitu scripts with YAC
 
 # Setup on levante
-TODO
+To setup the pamtra-insitu workflow on levante follow the following steps:
+
+Create and activate a python environment (do **not** use the python executable that comes with `module load python3`)
+```bash
+/sw/spack-levante/python-3.9.9-fwvsvi/bin/python -m venv venv --prompt pamtra-insitu
+. venv/bin/activate
+pip install --upgrade pip
+pip install wheel numpy matplotlib scipy numexpr netcdf4 cython
+```
+
+Build Pamtra and install it in your venv
+```bash
+git clone --recursive https://github.com/igmk/pamtra.git
+cd pamtra
+spack load /bcn7mbu # gcc
+
+# Now, let's modify the Makefile for openblas
+sed 's/-llapack//g' Makefile > Makefile.levante
+sed -i 's%-lblas% -L/sw/spack-levante/openblas-0.3.18-tpmfvw/lib/ -L/sw/spack-levante/fftw-3.3.10-fnfhvr/lib/ -lopenblas%g' Makefile.levante
+
+make -f Makefile.levante -j1
+
+# add rpath
+cd python/pyPamtra
+RPATH="$(patchelf --print-rpath pyPamtraLib*.so):/sw/spack-levante/fftw-3.3.10-fnfhvr/lib/:/sw/spack-levante/openblas-0.3.18-tpmfvw/lib/"
+patchelf --set-rpath ${RPATH} pyPamtraLib*.so
+cd -
+
+cp -r python/pyPamtra ../venv/lib64/python3.9/site-packages/
+
+cd ..
+```
+
+Build ICON
+```bash
+curl -s -L  https://gitlab.dkrz.de/icon/icon-model/-/archive/release-2024.07-public/icon-model-release-2024.07-public.tar.gz | tar xzf -
+mv icon-model-release-2024.07-public/ icon
+cd icon
+mkdir build
+cd build
+../config/dkrz/levante.gcc --enable-opnemp --enable-python-bindings --with-pic
+make -j32
+pip install externals/yac/python
+```
+With this pamtra, yac and icon should be in place and ready to use.
+
+# Prepare runscripts
+To attach a pamtra component to ICON you need to modify the runscript as follows:
+
+To enable the "output_coupling" add `coupled_to_ocean = .TRUE.` to the `coupling_mode_nml`:
+```
+&coupling_mode_nml
+  coupled_to_ocean = .TRUE.
+/
+```
+
+The we need to add an additional python process to MPI. We use the `--multi-prog` feature of `srun`.
+Add this just before the `srun` (`${START}`) call
+```bash
+cat > mpmd.conf << EOF
+/path/to/venv/bin/python path/to/pamtra/component.py
+* ${MODEL}
+EOF
+```
+(adjust the pathes) and replace the line
+```
+${START} ${MODEL}
+```
+with
+```
+${START} --multi-prog mpmd.conf
+```
+(This does only work with slurm.)