Antarctic sea ice climatology, variability, and late twentieth-century change in CCSM4
A preindustrial control run and an ensemble of twentieth-century integrations of the Community Climate System Model, version 4 (CCSM4), are evaluated for Antarctic sea ice climatology, modes of variability, trends, and covariance with related physical variables such as surface temperature and sea le...
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American Meteorological Society
2012
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ftncar:oai:drupal-site.org:articles_12175 2023-09-05T13:13:42+02:00 Antarctic sea ice climatology, variability, and late twentieth-century change in CCSM4 Landrum, Laura (author) Holland, Marika (author) Schneider, David (author) Hunke, Elizabeth (author) 2012-07 application/pdf http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-011-035 https://doi.org/10.1175/JCLI-D-11-00289.1 en eng American Meteorological Society Journal of Climate http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-011-035 doi:10.1175/JCLI-D-11-00289.1 ark:/85065/d7gf0v7f Copyright 2012 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work. Text article 2012 ftncar https://doi.org/10.1175/JCLI-D-11-00289.1 2023-08-14T18:39:15Z A preindustrial control run and an ensemble of twentieth-century integrations of the Community Climate System Model, version 4 (CCSM4), are evaluated for Antarctic sea ice climatology, modes of variability, trends, and covariance with related physical variables such as surface temperature and sea level pressure. Compared to observations, the mean ice cover is too extensive in all months. This is in part related to excessively strong westerly winds over ~50°-60°S, which drive a large equatorward meridional ice transport and enhanced ice growth near the continent and also connected with a cold bias in the Southern Ocean. In spite of these biases in the climatology, the model’s sea ice variability compares well to observations. The leading mode of austral winter sea ice concentration exhibits a dipole structure with anomalies of opposite sign in the Atlantic and Pacific sectors. Both the El Niño-Southern Oscillation and the southern annular mode (SAM) project onto this mode. In twentieth-century integrations, Antarctic sea ice area exhibits significant decreasing annual trends in all six ensemble members from 1950 to 2005, in apparent contrast to observations that suggest a modest ice area increase since 1979. Two ensemble members show insignificant changes when restricted to 1979-2005. The ensemble mean shows a significant increase in the austral summer SAM index over 1960-2005 and 1979-2005 that compares well with the observed SAM trend. However, Antarctic warming and sea ice loss in the model are closely connected to each other and not to the trend in the SAM. Article in Journal/Newspaper Antarc* Antarctic Sea ice Southern Ocean OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) Antarctic Southern Ocean Austral Pacific Journal of Climate 25 14 4817 4838 |
institution |
Open Polar |
collection |
OpenSky (NCAR/UCAR - National Center for Atmospheric Research/University Corporation for Atmospheric Research) |
op_collection_id |
ftncar |
language |
English |
description |
A preindustrial control run and an ensemble of twentieth-century integrations of the Community Climate System Model, version 4 (CCSM4), are evaluated for Antarctic sea ice climatology, modes of variability, trends, and covariance with related physical variables such as surface temperature and sea level pressure. Compared to observations, the mean ice cover is too extensive in all months. This is in part related to excessively strong westerly winds over ~50°-60°S, which drive a large equatorward meridional ice transport and enhanced ice growth near the continent and also connected with a cold bias in the Southern Ocean. In spite of these biases in the climatology, the model’s sea ice variability compares well to observations. The leading mode of austral winter sea ice concentration exhibits a dipole structure with anomalies of opposite sign in the Atlantic and Pacific sectors. Both the El Niño-Southern Oscillation and the southern annular mode (SAM) project onto this mode. In twentieth-century integrations, Antarctic sea ice area exhibits significant decreasing annual trends in all six ensemble members from 1950 to 2005, in apparent contrast to observations that suggest a modest ice area increase since 1979. Two ensemble members show insignificant changes when restricted to 1979-2005. The ensemble mean shows a significant increase in the austral summer SAM index over 1960-2005 and 1979-2005 that compares well with the observed SAM trend. However, Antarctic warming and sea ice loss in the model are closely connected to each other and not to the trend in the SAM. |
author2 |
Landrum, Laura (author) Holland, Marika (author) Schneider, David (author) Hunke, Elizabeth (author) |
format |
Article in Journal/Newspaper |
title |
Antarctic sea ice climatology, variability, and late twentieth-century change in CCSM4 |
spellingShingle |
Antarctic sea ice climatology, variability, and late twentieth-century change in CCSM4 |
title_short |
Antarctic sea ice climatology, variability, and late twentieth-century change in CCSM4 |
title_full |
Antarctic sea ice climatology, variability, and late twentieth-century change in CCSM4 |
title_fullStr |
Antarctic sea ice climatology, variability, and late twentieth-century change in CCSM4 |
title_full_unstemmed |
Antarctic sea ice climatology, variability, and late twentieth-century change in CCSM4 |
title_sort |
antarctic sea ice climatology, variability, and late twentieth-century change in ccsm4 |
publisher |
American Meteorological Society |
publishDate |
2012 |
url |
http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-011-035 https://doi.org/10.1175/JCLI-D-11-00289.1 |
geographic |
Antarctic Southern Ocean Austral Pacific |
geographic_facet |
Antarctic Southern Ocean Austral Pacific |
genre |
Antarc* Antarctic Sea ice Southern Ocean |
genre_facet |
Antarc* Antarctic Sea ice Southern Ocean |
op_relation |
Journal of Climate http://nldr.library.ucar.edu/repository/collections/OSGC-000-000-011-035 doi:10.1175/JCLI-D-11-00289.1 ark:/85065/d7gf0v7f |
op_rights |
Copyright 2012 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work. |
op_doi |
https://doi.org/10.1175/JCLI-D-11-00289.1 |
container_title |
Journal of Climate |
container_volume |
25 |
container_issue |
14 |
container_start_page |
4817 |
op_container_end_page |
4838 |
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1776204884562935808 |