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Modeled Trends in Antarctic Sea Ice Thickness

Modeled Trends in Antarctic Sea Ice Thickness Unlike the rapid sea ice losses reported in the Arctic, satellite observations show an overall increase in Antarctic sea ice concentration over recent decades. However, observations of decadal trends in Antarctic ice thickness, and hence ice volume, do not currently exist. In this study a model of the Southern Ocean and its sea ice, forced by atmospheric reanalyses, is used to assess 1992–2010 trends in ice thickness and volume. The model successfully reproduces observations of mean ice concentration, thickness, and drift, and decadal trends in ice concentration and drift, imparting some confidence in the hindcasted trends in ice thickness. The model suggests that overall Antarctic sea ice volume has increased by approximately 30 km 3 yr −1 (0.4% yr −1 ) as an equal result of areal expansion (20 × 10 3 km 2 yr −1 or 0.2% yr −1 ) and thickening (1.5 mm yr −1 or 0.2% yr −1 ). This ice volume increase is an order of magnitude smaller than the Arctic decrease, and about half the size of the increased freshwater supply from the Antarctic Ice Sheet. Similarly to the observed ice concentration trends, the small overall increase in modeled ice volume is actually the residual of much larger opposing regional trends. Thickness changes near the ice edge follow observed concentration changes, with increasing concentration corresponding to increased thickness. Ice thickness increases are also found in the inner pack in the Amundsen and Weddell Seas, where the model suggests that observed ice-drift trends directed toward the coast have caused dynamical thickening in autumn and winter. Modeled changes are predominantly dynamic in origin in the Pacific sector and thermodynamic elsewhere. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Climate American Meteorological Society

Modeled Trends in Antarctic Sea Ice Thickness

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Publisher
American Meteorological Society
Copyright
Copyright © 2013 American Meteorological Society
ISSN
0894-8755
eISSN
1520-0442
DOI
10.1175/JCLI-D-13-00301.1
Publisher site
See Article on Publisher Site

Abstract

Unlike the rapid sea ice losses reported in the Arctic, satellite observations show an overall increase in Antarctic sea ice concentration over recent decades. However, observations of decadal trends in Antarctic ice thickness, and hence ice volume, do not currently exist. In this study a model of the Southern Ocean and its sea ice, forced by atmospheric reanalyses, is used to assess 1992–2010 trends in ice thickness and volume. The model successfully reproduces observations of mean ice concentration, thickness, and drift, and decadal trends in ice concentration and drift, imparting some confidence in the hindcasted trends in ice thickness. The model suggests that overall Antarctic sea ice volume has increased by approximately 30 km 3 yr −1 (0.4% yr −1 ) as an equal result of areal expansion (20 × 10 3 km 2 yr −1 or 0.2% yr −1 ) and thickening (1.5 mm yr −1 or 0.2% yr −1 ). This ice volume increase is an order of magnitude smaller than the Arctic decrease, and about half the size of the increased freshwater supply from the Antarctic Ice Sheet. Similarly to the observed ice concentration trends, the small overall increase in modeled ice volume is actually the residual of much larger opposing regional trends. Thickness changes near the ice edge follow observed concentration changes, with increasing concentration corresponding to increased thickness. Ice thickness increases are also found in the inner pack in the Amundsen and Weddell Seas, where the model suggests that observed ice-drift trends directed toward the coast have caused dynamical thickening in autumn and winter. Modeled changes are predominantly dynamic in origin in the Pacific sector and thermodynamic elsewhere.

Journal

Journal of Climate – American Meteorological Society

Published: May 30, 2013

References

  • Representation of topography by shaved cells in a height coordinate ocean model
    Adcroft
  • Important role for ocean warming and increased ice-shelf melt in Antarctic sea-ice expansion
    Bintanja
  • The influence of sea ice on ocean heat uptake in response to increasing CO2
    Bitz