Flexible Earth System Modelling on Multiple Grids

There is a drive to increase the model complexity to include ever more processes of the whole Earth system. Some of these processes may require computations on grids of different type or resolution than the atmospheric grid. Multiple grid structures may be required as part of the numerical filtering strategy for atmospheric wave motions or to simply save computational cost of selected physical processes. These different grids may have different domain decompositions for parallel computations, and different parallelisation strategies.

The presentation demonstrates how Atlas, a new library developed at ECMWF, complements ECMWF's Integrated Forecasting System (IFS) model to enable a number of physical processes on multiple grids. Different remapping strategies are compared to couple fields between the atmospheric grid and physical process grids.

Atlas helps to accommodate flexibility in hardware and software choices as well as increasing model complexity.