Variability and predictability of 200-mb seasonal mean heights during summer and winter

In this paper a comparison of the variability and predictability of 200-mb seasonal mean heights for winter and summer is made based upon atmospheric general circulation model (AGCM) simulations. Simulations from two different AGCMs for the 1982-1999 period are used. The magnitude of seasonal predictability for the winter and summer is found to be similar. The spatial characteristics of seasonal predictability, however, had some interesting differences. For the respective hemisphere's summer the extratropical zonal mean heights had an appreciable contribution towards seasonal predictability, whereas for the winter season, predictability was dominated by eddy heights. There were also interesting interhemispheric differences in seasonal variability and predictability which are attributed to an interplay between the seasonal cycle of El Nino-Southern Oscillation SST anomalies and the seasonal cycle of mean atmospheric circulation which governs the dynamics of tropical-extratropical interactions.