Seasonal Relationships between Large-Scale Climate Variability and Antarctic Sea Ice Concentration

The observed relationships between anomalous Antarctic sea ice concentration (SIC) and the leading patterns of Southern Hemisphere (SH) large-scale climate variability are examined as a function of season over 1980–2008. Particular emphasis is placed on 1) the interactions between SIC, the southern...

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Bibliographic Details
Main Authors: Graham R. Simpkins, Laura, M. Ciasto, David W. J. Thompson, Matthew H. England
Other Authors: The Pennsylvania State University CiteSeerX Archives
Format: Text
Language:English
Published: 2011
Subjects:
Antarctic
Austral
Weddell
Antarc*
Sea ice
Online Access:http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.682.9813
http://web.science.unsw.edu.au/%7Ematthew/sea-ice-paper-JClim-2012.pdf
Description
Summary:The observed relationships between anomalous Antarctic sea ice concentration (SIC) and the leading patterns of Southern Hemisphere (SH) large-scale climate variability are examined as a function of season over 1980–2008. Particular emphasis is placed on 1) the interactions between SIC, the southern annular mode (SAM), and El Niño–SouthernOscillation (ENSO); and 2) the contribution of these two leadingmodes to the 29-yr trends in sea ice. Regression, composite, and principal component analyses highlight a seasonality in SH sea ice–atmosphere interactions, whereby Antarctic sea ice variability exhibits the strongest linkages to the SAM and ENSO during the austral cold seasonmonths. As noted in previous work, a dipole in SIC anomalies emerges in relation to the SAM, characterized by centers of action located near the Bellingshausen/Weddell and Amundsen/eastern Ross Seas. The structure and magnitude of this SIC dipole is found to vary consid-erably as a function of season, consistent with the seasonality of the overlying atmospheric circulation anomalies. Relative to the SAM, the pattern of sea ice anomalies linked to ENSO exhibits a similar sea-sonality but tends to be weaker in amplitude and more diffuse in structure. The relationships between ENSO and sea ice also exhibit a substantial nonlinear component, highlighting the need to consider both season and phase of the ENSO cycle when diagnosing ENSO–SIC linkages. Trends in SIC over 1980–2008 are not sig-nificantly related to trends in either the SAMor ENSO during any season, including austral summer when the trend in the SAM is most pronounced. 1.

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