Development of the global multiscale atmosphere model: computational aspects

Abstract The global atmosphere model SL-AV is applied for operational numerical weather prediction in Russia at the time scales from days to month and also for simulation of modern climate. It is important to achieve the best wall-clock time for all of the model applications with different grid sizes. In this paper, we analyse the effect of switching computations and parallel exchanges from double to single precision in the semi-Lagrangian advection and elliptic equations solver blocks on the quality of the medium-range forecast and evaluate the change in wall-clock time. We have also optimized OpenMP parallelization in the computations of the right-hand sides of meteorological prognostic equations. The effect of these changes is studied for SL-AV model versions with different resolutions.