An analysis has been made of the interseasonal and interannual variability of mean circulation and eddy statistics for both summer and winter in the Southern Hemisphere. Total variance fields of geopotential height, the noith-wuth and east-west wind components and poleward transient eddy momentum fluxes at 500 mb are analyzed along with their contributions from two broad frequency bands covering 2-8 day and 8-64 day period fluctuations. Largest interannual variability occurs between 40-60°S in association with the main jet stream in summer or the polar jet stream in winter and the main belt of eddy activity within each season. The circulation and eddy statistics during the year of the Global Weather Experiment (GWE) are compared with the means and standard deviations over all years from 1972–80, and contrasted with individual years The GWE summer of 1978–79 is contrasted with 1976–77, and the 1979 winter is contrasted with 1980. The year of the GWE was charactrized by an exceptionally deep circum... Abstract An analysis has been made of the interseasonal and interannual variability of mean circulation and eddy statistics for both summer and winter in the Southern Hemisphere. Total variance fields of geopotential height, the noith-wuth and east-west wind components and poleward transient eddy momentum fluxes at 500 mb are analyzed along with their contributions from two broad frequency bands covering 2-8 day and 8-64 day period fluctuations. Largest interannual variability occurs between 40-60°S in association with the main jet stream in summer or the polar jet stream in winter and the main belt of eddy activity within each season. The circulation and eddy statistics during the year of the Global Weather Experiment (GWE) are compared with the means and standard deviations over all years from 1972–80, and contrasted with individual years The GWE summer of 1978–79 is contrasted with 1976–77, and the 1979 winter is contrasted with 1980. The year of the GWE was charactrized by an exceptionally deep circum...