Some regional groups focus on using modelling tools and do not contribute to the development. One exception is the contribution of CyI to the development of the EMAC model. While initially EMAC was developed at MPIC, today the development is distributed over multiple institutions. CyI plays a very active role in the implementation of chemical and physical processes. The core areas of these activities are aerosol microphysics and aerosol optical properties. CyI also carries out performance analysis and optimizes the code accordingly. Moreover, the group aims at porting the EMAC model to the next generation of supercomputing platforms.