The characteristics of, and the mechanisms causing, multi-decadal variability are currently receiving much attention. This undertaking is particularly challenging in the sub-Antarctic region because of the paucity of data, and the complexity of the governing physical processes.
In this paper we report on aspects of high-southern-latitude variability which appear in the European Centre for Medium-range Weather Forecasts twice-daily analyses for the period 1 January 1980 to 31 August 1996 and in the results of global climate model experiments. We show that the number of cyclone positions in the 50-70°S latitude band exhibits considerable interannual variability, as well as changes on longer time-scales. The seasonal distribution of cyclones is linked with the “semi-annual oscillation". We show that the variability of this phenomenon in a 1000 year run of the GFDL coupled model shows “red” characteristics fand on decadal time-scales is similar to that displayed in the available observationsi. The interaction with the ocean and sea ice is siressed as an important factor in determining the nature of climate variability in sub-Antarctic latitudes.