Global Semi-lagrangian Atmospheric Model Based on Compact Nite-diierences and Its Implementation on a Parallel Computer

The semi-Lagrangian atmospheric model on the sphere based on compact nite diierences is presented. In the two-dimensional case, the potential vorticity is used as one of the prognostic variables. Fourth-order compact nite diierences are used to discretize rst-and second-order derivatives. The results including real data tests presented for 2D shallow water version with orography demonstrate its accuracy with the time steps several times greater than in Eulerian model. The 3D version of the model uses the absolute vorticity equation. Some results including a real data forecast are presented. The parallel implementation of the 3D model on a distributed memory parallel computer is described.