The main task of WP2 is to better model clouds using large eddy simulations (LES) and single-column models (SCM) and to improve cloud parameterization in numerical weather prediction (NWP) and global climate models (GCMs). This task is directly relevant for solar power assessment and prediction on scales from local to global. A hierarchy of models, from LES to GCM, will be used. For example, the LES results serve as a virtual laboratory for testing and evaluation of the cloud schemes in GCMs. In turn, the GCM simulations allow the investigation whether the parameterizations constructed based on LES/SCM results are effective in large-scale models. The hierarchy of models allows a more informed study of the role of small-scale processes in feedbacks in the climate system. The model simulations will emphasis on achieving a realistic cloud/solar power simulation at the Jülich Observatory for Cloud Evolution (JOYCE) site for benchmarking the cloud/solar simulation in central Europe and contribute to the global effort for benchmarking cloud/solar simulation on the global scale. An archive of cloud simulations for the Jülich area will be generated, that is continuous in time and covers a period of many years. This archive will be made available to the international community for cloud/solar-power research and development. Many research groups in the atmospheric and renewable energy sciences have expressed the need for such a reference dataset for a variety of purposes. This outreach could stimulate cooperation beyond the bounds of our own research field, and thus drive scientific progress. The dataset can also act as an important educational tool, as it provides students a realistic insight into the dynamics of turbulence and convection. Funding is needed for the installation of a local simulation lab though the most demanding simulation shall be made via HPSC TerrSys.

• Dr. Maren Brast (IGM)
• Dr. Sara Dal Gesso (IGM)
• Prof. Dr. Stefan Kollet (HPSC TerrSys, Geoverbund ABC/J)
• Prof. Dr. Ulrich Lang (RRZK)
• Dr. Sabine Lennartz-Sassinek (IGM)
• Prof. Dr. Roel Neggers (IGM)
• Prof. Dr. Yaping Shao (IGM)