This talk will provide an overview on different tasks and activities during the last years connected to my position at DWD. Retrospectively, a reoccurring aspect in most of these topics is the creation and intensification of an ICON community. Examples are supporting the transition of COSMO partners (i.e. national meteorological services) from the COSMO-model to the ICON model, the organization of training courses and scientific conferences around the ICON model, providing documentation or participating in the creation of platforms like the grid & external parameter web interface Zonda.
 
Finally, some more scientific aspects will be highlighted. Examples are the inclusion of the ecRad radiation model into the ICON code and the introduction of a simplified prognostic aerosol scheme which can also be combined with ICON-ART. While ecRad is operational for several years already, the simplified prognostic aerosol is currently undertaking the final steps towards operationalization. I will present the idea behind the simplifications, show comparisons with measurements and verification results from a full forecast cycle experiment.

(1) tbd (2) tbd (3) tbd (4) tbd

Ice nucleating particles (INPs) strongly influence cloud phase, precipitation, and radiative properties, yet observations of their vertical distributions remain sparse. This presentation reviews recent advances in airborne INP measurements using drones, launched balloons, and tethered balloon systems, focusing on the development of the Profiling Upper altitudes For Ice Nucleation (PUFIN) sampler for routine altitude-resolved observations. Results from multiple deployments demonstrate that INP concentrations can vary substantially with height, season, aerosol source, and boundary layer structure, highlighting the limitations of relying solely on surface measurements. These vertically resolved observations provide critical constraints for understanding aerosol-cloud interactions and improving the representation of ice formation processes in atmospheric models.

(1) Predictability of the 2014 Pentecost storm (2) tbd (3) Added-Value of the Coming Decade ICONXPP Decadal Climate Predictions Ensemble for User-relevant Variables in Europe (4) tbd 

Influences of aerosols on climate are qualitatively known, but the magnitude of their effects is uncertain with important implication for understanding past and future climate change. In this colloquium, I will explain some reasons for uncertainties in our understanding of aerosol effects on climate, and outline how we can make progress despite persistent multi-model spread in aerosol radiative forcing. We will see model-to-model differences for aerosol effects from global climate model simulations, and new CMIP aerosol data for use in climate simulations that inform the next IPCC assessment report of climate change. Looking ahead, I will introduce some of the plans for advancing the research field, e.g., through leading the new experiment protocol of the Aerosol and Chemistry Model Intercomparison Project, to which the most complex Earth system models currently available worldwide will contribute simulations.