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AGU: Journal of Geophysical Research, Oceans

 

Keywords

  • Amundsen Sea
  • Antarctica
  • Pine Island Bay
  • methanesulfonic acid
  • polynyas
  • sea ice

Index Terms

  • 0724 - Ice cores
  • 0750 - Sea ice
  • 0752 - Polynas

Paper in Press

JOURNAL OF GEOPHYSICAL RESEARCH, doi:10.1029/2012JC008077

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

Key Points
  • MSA is primarily derived from polynya biological productivity in summer
  • Cl- originates primarily from winter sea-ice formation processes
  • Ice-core records may provide a proxy for reconstructing polynya variability

Authors:

Alison Sara Criscitiello

Sarah B Das

Matthew J Evans

Karen E. Frey

Howard Conway

Ian Joughin

Brooke Medley

Eric Steig

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 (PIB) polynyas. Based on this result we evaluate the use of ice-core chemistry as a proxy for inter-annual 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 PIB polynya variability prior to the satellite era.

Received 22 March 2012; accepted 3 November 2012.

Citation: Criscitiello, A. S., S. B. Das, M. J. Evans, K. E. Frey, H. Conway, I. Joughin, B. Medley, and E. Steig (2012), Ice-sheet record of recent sea-ice behavior and polynya variability in the Amundsen Sea, West Antarctica, J. Geophys. Res., doi:10.1029/2012JC008077, in press.