SL-AV model: numerical weather prediction at extra-massively parallel supercomputer

Abstract

The SL-AV global atmosphere model is used for operational medium-range and long-range forecasts at Hydrometcentre of Russia. The program complex uses the combination of MPI and OpenMP technologies. Currently, a new version of the model with the horizontal resolution about 10 km is being developed. In 2017, preliminary experiments have shown the scalability of the SL-AV model program complex up to 9000 processor cores with the efficiency of about 45% for grid dimensions of 3024 × 1513 × 51. The profiling analysis for these experiments revealed bottlenecks of the code: non-optimal memory access in OpenMP threads in some parts of the code, time losses in the MPI data exchanges in the dynamical core, and the necessity to replace some numerical algorithms. The review of model code improvements targeting the increase of its parallel efficiency is presented. The new code is tested at the new Cray XC40 supercomputer installed at Roshydromet Main Computer Center.