Year-to-year variability in East Antarctic sea ice seasonality shown in example maps of annual anomalies versus the long-term mean (1979/80–2009/10).

<p>A)–C) Anomaly maps of advance and retreat and resultant season duration, respectively, for 1980/81. D)–F) Anomaly maps of advance and retreat and resultant season duration, respectively, for 1999/2000. G)–I) Anomaly maps of advance and retreat and resultant season duration, respectively, 2004/05. The black lines depict the location of the meridional transects marked in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0064756#pone-0064756-g004" target="_blank">Figure 4</a>.