After three years preparation and discussion, the European ICON weather services model system becomes Open Source, institutions communicated in February 2024.
ICON (for ICOsahedral Non-hydrostatic modeling framework) is developed by five European partners:

• the Swiss Center for Climate Systems Modeling (Federal Office for Meteorology and Climatology MeteoSchweiz and ETH Zurich as C2SM partners), 
• the German Climate Computing Center (DKRZ), 
• the German Weather Service (DWD), 
• the Karlsruhe Institute for Technology (KIT)
• the Max Planck Institute for Meteorology (MPI-M). 

The ICON model enables efficient weather forecasts and climate projections, of which, in addition to the research community, the entire society will benefit. Providing the code was an important step to building trust and progress towards more open, transparent, quality assured and collaborative science. Researchers worldwide will have the opportunity to work, build and jointly implement models for weather forecasts and perform more efficient climate simulations.

It was decided to apply the BSD-3-Clause permissive license to the source code, which allows for the widest use, including commercial, and opens later possibilities for stakeholders to license improvements and specific derivatives under licenses better granting that the communicated code will remain public, like the EUPL or similar reciprocal licenses. 

"Making the ICON model code open source not only helps to intensify cooperation between research and national weather services, but also offers society as a whole the opportunity to benefit from the most modern developments in the world of climate and weather research," says Prof. Roland Potthast, head of the department Meteorological analysis and modeling at the German Weather Service.

The open source release strengthens Europe's position in the field of climate and enables more efficient collaboration with supercomputers manufacturers, since they need to optimize the performance of their hardware for testing and improving climate models.

The published communiqué is attached.

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