Ice sheet record of recent sea-ice behavior and polynya variability in the Amundsen Sea, West Antarctica

Authors

  • Alison S. Criscitiello,

    Corresponding author
    1. MIT/WHOI Joint Program in Oceanography/Applied Ocean Sciences and Engineering, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
    2. Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
    • Corresponding author: A. S. Criscitiello, Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA. (acriscitiello@whoi.edu)

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  • Sarah B. Das,

    1. Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
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  • Matthew J. Evans,

    1. Department of Chemistry, Wheaton College, Norton, Massachusetts
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  • Karen E. Frey,

    1. Graduate School of Geography, Clark University, Worcester, Massachusetts, USA
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  • Howard Conway,

    1. Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
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  • Ian Joughin,

    1. Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
    2. Applied Physics Laboratory, University of Washington, Seattle, Washington, USA
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  • Brooke Medley,

    1. Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
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  • Eric J. Steig

    1. Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
    2. Quaternary Research Center, University of Washington, Seattle, Washington, USA
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Abstract

[1] Our understanding of past sea-ice variability is limited by the short length of satellite and instrumental records. Proxy records can extend these observations but require further development and validation. We compare methanesulfonic acid (MSA) and chloride (Cl) concentrations from a new firn core from coastal West Antarctica with satellite-derived observations of regional sea-ice concentration (SIC) in the Amundsen Sea (AS) to evaluate spatial and temporal correlations from 2002–2010. The high accumulation rate (~39 g∙cm–2∙yr–1) provides monthly resolved records of MSA and Cl, allowing detailed investigation of how regional SIC is recorded in the ice-sheet stratigraphy. Over the period 2002–2010 we find that the ice-sheet chemistry is significantly correlated with SIC variability within the AS and Pine Island Bay polynyas. Based on this result, we evaluate the use of ice-core chemistry as a proxy for interannual polynya variability in this region, one of the largest and most persistent polynya areas in Antarctica. MSA concentrations correlate strongly with summer SIC within the polynya regions, consistent with MSA at this site being derived from marine biological productivity during the spring and summer. Cl concentrations correlate strongly with winter SIC within the polynyas as well as some regions outside the polynyas, consistent with Cl at this site originating primarily from winter sea-ice formation. Spatial correlations were generally insignificant outside of the polynya areas, with some notable exceptions. Ice-core glaciochemical records from this dynamic region thus may provide a proxy for reconstructing AS and Pine Island Bay polynya variability prior to the satellite era.

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