Previous studies have shown strong contrasting trends in annual sea ice duration and in monthly sea ice concentration in two regions of the Southern Ocean: decreases in the western Antarctic Peninsula/southern Bellingshausen Sea ( wAP/sBS) region and increases in the western Ross Sea ( wRS) region. To better understand the evolution of these regional sea ice trends, we utilize the full temporal ( quasi-daily) resolution of satellite-derived sea ice data to track spatially the annual ice edge advance and retreat from 1979 to 2004. These newly analyzed data reveal that sea ice is retreating 31 +/- 10 days earlier and advancing 54 +/- 9 days later in the wAP/sBS region ( i.e., total change over 1979 - 2004), whereas in the wRS region, sea ice is retreating 29 +/- 6 days later and advancing 31 +/- 6 days earlier. Changes in the wAP/sBS and wRS regions, particularly as observed during sea ice advance, occurred in association with decadal changes in the mean state of the Southern Annular Mode ( SAM; negative in the 1980s and positive in the 1990s) and the high-latitude response to El Nino - Southern Oscillation ( ENSO). In general, the high-latitude ice-atmosphere response to ENSO was strongest when - SAM was coincident with El Nino and when +SAM was coincident with La Nina, particularly in the wAP/sBS region. In total, there were 7 of 11 -SAMs between 1980 and 1990 and the 7 of 10 +SAMs between 1991 and 2000 that were associated with consistent decadal sea ice changes in the wAP/sBS and wRS regions, respectively. Elsewhere, ENSO/SAM-related sea ice changes were not as consistent over time ( e. g., western Weddell, Amundsen, and eastern Ross Sea region), or variability in general was high ( e. g., central/ eastern Weddell and along East Antarctica).
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