Mgo T63l25 Seasonal Prediction Model With New Parameterization Schemes

New parameterization schemes of the physical processes in the atmosphere are briefly described that are incorporated in both the T63L25 Atmospheric General Circulation Model (AGCM, 2023) and the Slab OceanModel that includes AGCM and mixed layer ocean with thermodynamic sea ice (AGCM-SOM, 2023). The models were tested in the computation of 30-year sets of historical forecasts on subseasonal and seasonal timescales. The results showed an increase in forecast skill as compared to those based on the preceding model version (AGCM, 2017), particularly in the tropics. Some statistically significant improvements were obtained for surface and 850 hPa air temperatures, sea level pressure, and particularly for precipitation. Less significant improvements were observed in extratropical regions.