|Title||Reorganization of the radiation transfer calculations in the ECMWF IFS|
|Publication Type||Technical memorandum|
|Secondary Title||ECMWF Technical Memorandum|
|Authors||Mozdzynski, G, Morcrette, J-J|
Radiation computations in IFS are a relatively expensive part of a high resolution forecast model taking approximately 10 percent of the total time. This current level of cost is achieved by running the radiation scheme only once every forecast hour and by using a radiation grid resolution which is coarser than that of the model grid. This technical memorandum investigates a new approach for the radiation scheme where the radiation computations execute in separate tasks from the rest of the model, with the objective of improved scalability and performance. The approach serves as an example that could be applied to other parts of IFS as scalability becomes increasingly more challenging on future supercomputers.