Understanding the Seasonal Cycle of Antarctic Sea Ice Extent in the Context of Longer-Term Variability

Clare Eayrs, David Holland, Diana Francis, Till Wagner, Rajesh Kumar, Xichen Li

Research output: Contribution to journalReview article

Abstract

Over the 40-year satellite record, there has been a slight increasing trend in total annual mean Antarctic sea ice extent of approximately 1.5% per decade that is made up of the sum of significantly larger opposing regional trends. However, record increases in total Antarctic sea ice extent were observed during 2012–2014, followed by record lows (for the satellite era) through 2018. There is still no consensus on the main drivers of these trends, but it is generally believed that the atmosphere plays a significant role and that seasonal time scales and regional scale processes are important. Despite considerable yearly and regional variability, the mean seasonal cycle of growth and melt of Antarctic sea ice is strikingly consistent, with a slow growth but fast melt season. If we are to project trends in Antarctic sea ice and understand changes on longer time scales, we need to understand the mechanisms related to the seasonal cycle separately from those that drive variability. Twice-yearly changes in the position and intensity of the zonal winds circling Antarctica are thought to drive the system by working with or against the evolving sea ice edge to slow the autumn advance and hasten the spring melt. Open water regions, created by divergence associated with the zonal winds, amplify the spring melt through increased warming of the upper ocean. Climate models fail to accurately reproduce mean Antarctic sea ice extent and overestimate its year-to-year variability, but they tend to capture the pattern and timing of the Antarctic seasonal cycle.

Original languageEnglish (US)
Pages (from-to)1037-1064
Number of pages28
JournalReviews of Geophysics
Volume57
Issue number3
DOIs
StatePublished - Sep 1 2019

Keywords

  • Antarctic
  • climate modeling
  • ice-ocean albedo feedback
  • satellite observations
  • sea ice
  • semiannual oscillation

ASJC Scopus subject areas

  • Geophysics

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