1. An Analysis of the Variability of Cyclones Around Antarctica and Their Relationship to Sea-Ice Extent.
- Author
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Howarth, David A.
- Subjects
- *
CYCLONES , *OCEAN , *ICE , *CLIMATOLOGY , *PHYSICAL geography - Abstract
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]
- Published
- 1983
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