The key role of the Southern Annular Mode during the sea-ice maximum for Antarctic sea ice and its recent loss

Boehm, Chloe L., Thompson, David W. J. and Blanchard-Wrigglesworth, Edward (2025) The key role of the Southern Annular Mode during the sea-ice maximum for Antarctic sea ice and its recent loss. Communications Earth and Environment, 6 (1). ISSN 2662-4435

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Abstract

Antarctic sea ice exhibits considerable interannual variability and has experienced unprecedented decline over the past decade. Here we provide observational insights into the role of the Southern Annular Mode in driving such variations in Antarctic sea-ice area. The influence of the Southern Annular Mode on Antarctic sea-ice area exhibits more pronounced seasonality than indicated in previous work. Positive anomalies in the Southern Annular Mode lead to decreases in sea-ice area during the seasonal sea-ice maximum, but vice versa during the sea-ice minimum. Variations in Southern Annular Mode during the sea-ice maximum also have an outsized influence on annual-mean changes in sea-ice area, since the seasonally-varying persistence and shortwave effects of sea-ice anomalies peak during the following months. It is argued that a notable fraction of the dramatic losses in annual-mean sea-ice area over the past decade can be traced to variations in the Southern Annular Mode during the sea-ice maximum.

Item Type:	Article
Additional Information:	Data availability: The NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration, Version 4 data can be found at https://nsidc.org/data/g02202/versions/4, and the Near-Real-Time NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration, Version 2 data can be found at https://nsidc.org/data/g10016/versions/2. The SAM index data from the NOAA CPC can be found at https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/aao/aao.shtml. The Niño3.4 index data from the NOAA CPC can be found at https://psl.noaa.gov/data/timeseries/month/Nino34_CPC/. ERA5 data can be found at 10.24381/cds.f17050d7. CERES-EBAF surface flux data can be found at https://ceres.larc.nasa.gov/data/. CESM2 data output can be found at https://cseg.cgd.ucar.edu/experiments/public/. Figures were created using the Python package Proplot https://proplot.readthedocs.io/en/latest/index.html. Code availability: The code to process the data and create the figures is publicly available at https://doi.org/10.5281/zenodo.1694339883.
Uncontrolled Keywords:	environmental science(all),earth and planetary sciences(all) ,/dk/atira/pure/subjectarea/asjc/2300
Faculty \ School:	Faculty of Science > School of Environmental Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Climatic Research Unit Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Related URLs:	http://www.scopus.com/inward/record.url?...
Depositing User:	LivePure Connector
Date Deposited:	09 Apr 2026 14:30
Last Modified:	13 Apr 2026 10:34
URI:	https://ueaeprints.uea.ac.uk/id/eprint/102736
DOI:	10.1038/s43247-025-02792-2

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