Large-Scale Variations in Observed Antarctic Sea Ice Extent and Associated Atmospheric Circulation

Abstract The 1974 3-day averaged sea ice extent data for the Southern Ocean determined from the Electrically Scanning Microwave Radiometer aboard Nimbus 5 have been compared with 1000 mb temperature and sea level pressure fields from the Southern Hemisphere meteorological data set of the Australian Bureau of Meteorology. A Fourier decomposition of each of these variables defines the dominant spatial scales during the course of the year. The first three harmonics are sufficient to explain most of the variance of the ice extent and temperature for any 3-day period during the year, with the pressure field generally requiring at least the first four. Three case studies are presented to illustrate ice/atmosphere associations for different times of the year. For the period mid-March through mid-May a correspondence is found between the phase of harmonic 2 in sea level pressure and regions of rapid ice growth. During a 2-week period in September, the month of maximum ice extent, the location of the circumpolar t...