Simulation of the seasonal atmospheric circulation with the new version of the semi-Lagrangian atmospheric model

Simulation of the atmospheric circulation on the seasonal scale with the new version of the global semi-Lagrangian model is considered. The new version includes land surface processes parameterization taking into account influence of the vegetation and also freezing and melting of soil moisture. The new version also includes improved parameterization for short and long wave radiation, cloudiness and atmospheric boundary layer. Ensembles of seasonal forecasts for all four seasons for 25 years were computed based on NCEP/NCAR reanalysis-2 data according to the protocol of the international experiment SMIP-2/HFP. Verifications scores for seasonally averaged circulation are presented. In the new version of model, accuracy of the simulation for the mean sea level pressure and 500 hPa height in tropics is significantly improved. On average, in the extratropical zones of Northern and Southern Hemispheres, the error measures decreased less significantly, with an exception for T850 errors. Using daily averaged data of the atmospheric circulation reproduced by the semi-Lagrangian atmospheric model, the empirical orthogonal functions (EOF) for H500 and mean sea level pressure fields are computed for winter and summer periods. They are compared to EOFs obtained from NCEP/NCAR reanalysis-2 data.