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Results of an analysis of the distribution and movement of extratropical cyclones around Antarctica for the period September, 1973, through May, 1975, are presented. Variations in seasonal cyclone frequencies, their preferred longitudinal positions, and the spatial and temporal fluctuations in latitude and pressure are shown, and these indicate good agreement temporal fluctuations in latitude and pressure are shown, and these indicate good agreement with the known features of Southern Hemisphere climatology. The greatest numbers of cyclones occur during spring and fall, and their most common locations are near coastal embayments. A semiannual oscillation is present in the frequencies, mean latitudes, and mean pressures of the cyclones, although to varying degrees. Longitudinal variations in the intensity of the oscillation are also evident. The belt of maximum cyclone activity exhibits a distinct half-yearly cycle in latitudinal position, although the trough is located some 5° north of the position determined from mean monthly pressures. Harmonic analysis of the spatial variation of this belt and the simultaneous position of the sea-ice margin derived from microwave imagery suggests that there is little correlation between sea ice and cyclone tracks on a hemispheric scale. Close relationships are apparent for short time periods or in specific regions but will require more intensive study before causal mechanisms can be suggested. The asymmetry of the continent, rather than the extent of sea ice, is probably the principal factor involved in determining the longitudinal variations in the positions and tracks of cyclones around Antarctica on a hemispheric scale. [ABSTRACT FROM AUTHOR]

The spatial variability of seasonal mean temperature departures at 26 stations around Antarctica, southern South America, and nearby islands is shown using factor analysis. An opposition in temperature anomalies between mainland stations and those on or near the An opposition in temperature anomalies between mainland stations and those on or near the Antarctic Peninsula is a recurring pattern of spatial variability in all seasons but spring. Other factors indicate that temperature anomalies alternate in sign around the continent and especially near the peninsula. The association between the spatial patterns of temperature variability and features of the atmospheric circulation at middle and higher latitudes of the Southern Hemisphere is also examined. In each season the time series of one factor is significantly associated with temporal variations in the strength of the 500 mb westerlies, measured using height differences across six pairs of middle-latitude and Antarctic stations. In winter and summer the westerlies are linked to the mainland/Peninsula temperature opposition pattern such that when zonal flow is anomalously strong, mainland stations are anomalously cold. In autumn and spring, temperature variability is highly related to meridional flow strength over New Zealand and in the lee of the Andes, and is associated with interannual longitudinal shifts in the positions of the climatological lows near the Antarctic coast. A deep Andes trough is associated with longer-than-usual ice duration at the South Orkneys. Historically, strong troughing and heavy sea-ice conditions in the South Atlantic occurred between 1920 and 1935. [ABSTRACT FROM AUTHOR]