Abstract
Synoptic weather systems play a crucial role in transporting moisture to Antarctica. Climate models project significant changes in these systems, including a wintertime intensification and a summertime poleward shift, with implications for Antarctic ice mass balance. Our analysis of CMIP6 model output shows synoptic moisture fluxes across the Antarctic Circle increasing by 2–6% per decade under high-emission scenarios, accounting for 24% of winter and 93% of summer total moisture transport trends. This increase is mainly associated with enhanced eddy moisture anomalies rather than stronger eddy wind anomalies that are often used to gauge storm track activity. Eddy-driven moisture variability also accounts for a substantial fraction of inter-model uncertainty in future projections. Furthermore, using a large-ensemble approach, we show that differences between reanalysis and multi-model mean externally forced trends could possibly be due to natural climatic variability, while potential model biases cannot be excluded.
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Data availability
MERRA-2 was obtained from the NASA Goddard Earth Sciences Data and Information Services Center (https://disc.gsfc.nasa.gov/datasets?project=MERRA-2). CFSR, CFSv2, and JRA-55 data were obtained from the research data archive (RDA; https://rda.ucar.edu/). ERA5 was obtained from the climate data store (https://doi.org/10.24381/cds.bd0915c6). CMIP6 model data were obtained from the Earth System Grid Federation (e.g. https://esgf-node.llnl.gov/projects/cmip6/). Code can be provided upon request.
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Acknowledgements
Patrick Martineau was supported in part by the Japan Society for the Promotion of Science (JSPS) through Grant-in-Aid for Scientific Research JP19H05702 and JP25H02094. Hua Lu and Thomas Bracegirdle are supported by the NERC through SURface FluxEs In AnTarctica project (NE/X009319/1). We are grateful to the European Centre for Medium-range Weather Forecasts (ECMWF) for making ERA5 data available. We acknowledge the World Climate Research Programme, which, through its Working Group on Coupled Modelling, coordinated and promoted CMIP6. We thank the climate modelling groups for producing and making available their model output, the Earth System Grid Federation (ESGF) for archiving the data and providing access, and the multiple funding agencies who support CMIP6 and ESGF.
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P.M. led and coordinated the various components of the study throughout. All authors (P.M., H.L., and T.B.) discussed the results and aided in their interpretation. P.M. took the lead in writing the manuscript.
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Martineau, P., Lu, H. & Bracegirdle, T.J. Projected and historical amplification of moisture fluxes towards Antarctica by synoptic eddies. npj Clim Atmos Sci (2026). https://doi.org/10.1038/s41612-026-01376-x
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DOI: https://doi.org/10.1038/s41612-026-01376-x
