Variability of Antarctic sea ice

Previous analysis of the Antarctic sea ice cover, as observed by satellite passive-microwave sensors beginning in 1973, showed significant inter-annual variations in the ice extent and the open water within the ice pack, but no significant long-term trend. In this paper, ice maps using several parameter-extraction algorithms and recalibrated Nimbus-7 SMMR data are compared with the Navy-NOAA ice maps, showing significant quantitative differences and the need to use a consistently calibrated and analyzed data set. Regional inter-annual variations in the sea ice area continue to be as large as 30%, compared to about 10% in the overall coverage. For periods of 3-5 years, more ice area in winter appears to be associated with less ice in summer. For longer periods, the changes are similar in all seasons. However, the overall change in ice extent over 15 years is not considered to be significant. Similarly, there is no significant change in the amount of open water within the ice pack