Interfaces & Tools#

Zonda: ICON Grid & EXTPAR Interface#

../_images/zonda.png

Zonda is a web interface designed to facilitate the generation of External Parameter data (EXTPAR) on ICON triangular grids for research and on-demand simulations. This is realized as a two-step process:

  1. In the frontend, the user specifies the domain(s) including the appropriate settings for the external parameter generation. Example configurations and an expert mode with additional choices are available to assist the user. As a result, the user gets a JSON code snippet which is required for the second step.

  2. In the backend, the JSON code has to be pasted into a github issue. Then, the github CI triggers the generation of the ICON Grid and EXTPAR data.

Zonda Access

Zonda is free to use, the only requirement is a github account. The Zonda web interface is available under https://zonda.ethz.ch/ and comes with documentation.

Please note that the grids and EXTPAR data generated by Zonda are targeted at the NWP physics package.

Coupling (YAC)#

YAC (Yet Another Coupler) is a flexible coupling library which comes with ICON. Its interface is compatible to the well-known OASIS coupler and it can be used as a full replacement of it. YAC supports many different horizontal interpolations and a unique interpolation stack to control alternatives in case direct interpolation is not feasible. It is not only used for coupling atmosphere and ocean components of ICON, but also for a highly flexible output method.

yac yac

YAC Documentation

You can find further information in the YAC Documentation.

Data Analysis & Remapping (CDO)#

CDO is a well know data anlysis tool developed by Max-Planck-Institute for Meteorology. CDO supports the ICON native horizontal grid so that ICON model output can be easily analysed.

Examples:

  • Horizontal interpolations can be done with a wide range of methods

  • Vertical interpolation from ICON (atm) vertical sigma hight coordinate with the ap2pl operator:

    • (optional) add CF-conform name for pressure with

    ncatted -O -a standard_name,pres,o,c,"air_pressure" <input> <output>     # using NCO

    or

    cdo -setattribute,pres@standard_name='air_pressure' <input> <output>

    • call the ap2pl operator in this case for a remapping to the 500 hPa and 825 hPa levels

    cdo ap2pl,50000,82500 <input> <output>

ICON forecast set with ecflow at ECMWF#

This suite provides an easy way to test ICON model physics. Short forecasts for January and July are performed and many plots are generated. References are the ICON or IFS analysis, a reference experiment and observations (CERES radiation, IMERG precipitation and WHOI ocean surface parameters). The tests are done on atos at ECMWF using an ecflow scheduler.

The following issues need to be considered:

  • apply for access to ECMWF computers and the ecflow server

  • compile ICON at ECMWF

  • ICON ECMWF scheduler code is part of the ICON repository here: schedulers/ecmwf. Key directories are suites (python ecflow setup), tasks and cases (namelists).

  • automatic transfer of plots to the DWD plot-catalog

More details are available here ICON at ECMWF: ecflow suite.

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