Exploring Sea Ice Indexes for Polar Ecosystem Studies

Abstract

N i _ r othing more dramatically illustrates the extreme seasonality of the Southern Ocean physical environment than the annual waxing and waning of sea ice over 20 million km2 of ocean. In winter, sea ice can almost double the surface area of the Antarctic continent, whereas in summer, sea ice covers approximately one-sixth of the area it covers in winter and is confined to just a few basins. These differences are as extreme as the perpetual night and day associated with those two seasons, except that seasonal changes in both the timing and magnitude of sea ice coverage are far more variable than seasonal changes in solar radiation. In this tempestuous environment, local atmospheric and oceanic forces shape the vast sea ice landscape of the Southern Ocean, creating not only high seasonal variability but also high spatial variability and, consequently, different regional sea ice environments (Zwally et al. 1983, Gloersen et al. 1992, Parkinson 1992, 1994).