Martineau et al. (2026) Projected and historical amplification of moisture fluxes towards Antarctica by synoptic eddies

Identification

• Journal: npj Climate and Atmospheric Science
• Year: 2026
• Date: 2026-04-02
• Authors: Patrick Martineau, Hua Lu, Thomas J. Bracegirdle
• DOI: 10.1038/s41612-026-01376-x

Research Groups

• Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan (Patrick Martineau)
• British Antarctic Survey, Cambridge, UK (Hua Lu, Thomas J. Bracegirdle)

Short Summary

This study investigates projected and historical changes in moisture fluxes towards Antarctica driven by synoptic eddies using CMIP6 models and reanalysis data. It finds a significant amplification of synoptic moisture fluxes across the Antarctic Circle, primarily due to enhanced eddy moisture anomalies, with implications for Antarctic ice mass balance.

Objective

• To quantify the projected and historical amplification of moisture fluxes towards Antarctica by synoptic eddies and understand the underlying mechanisms, particularly in the context of Antarctic ice mass balance.

Study Configuration

• Spatial Scale: Antarctic Circle, Antarctica, Southern Ocean.
• Temporal Scale: Historical period and future projections under high-emission scenarios (decadal trends, winter and summer seasons).

Methodology and Data

• Models used: Coupled Model Intercomparison Project Phase 6 (CMIP6) models.
• Data sources:
  • Reanalysis products: MERRA-2, CFSR, CFSv2, JRA-55, ERA5.
  • CMIP6 model output obtained from the Earth System Grid Federation (ESGF).

Main Results

• Synoptic moisture fluxes across the Antarctic Circle are projected to increase by 2–6% per decade under high-emission scenarios.
• This increase accounts for 24% of winter and 93% of summer total moisture transport trends.
• The amplification is mainly associated with enhanced eddy moisture anomalies, rather than stronger eddy wind anomalies.
• Eddy-driven moisture variability contributes substantially to inter-model uncertainty in future projections.
• Differences between reanalysis and multi-model mean externally forced trends could be attributed to natural climatic variability, though potential model biases cannot be excluded.

Contributions

• Provides a quantitative assessment of the projected and historical amplification of moisture fluxes towards Antarctica by synoptic eddies using a comprehensive suite of CMIP6 models.
• Identifies enhanced eddy moisture anomalies as the primary driver for increased moisture transport, distinguishing it from eddy wind anomalies often used to gauge storm track activity.
• Highlights the significant role of eddy-driven moisture variability in contributing to inter-model uncertainty in future climate projections for the Antarctic region.
• Offers insights into potential causes for discrepancies between reanalysis and model trends, suggesting the influence of natural climatic variability.

Funding

• Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Scientific Research JP19H05702 and JP25H02094.
• NERC SURface FluxEs In AnTarctica project (NE/X009319/1).
• European Centre for Medium-range Weather Forecasts (ECMWF) for ERA5 data.
• World Climate Research Programme (WCRP) Working Group on Coupled Modelling (CMIP6 coordination).
• Climate modelling groups, Earth System Grid Federation (ESGF), and multiple funding agencies supporting CMIP6 and ESGF.

Citation

@article{Martineau2026Projected,
  author = {Martineau, Patrick and Lu, Hua and Bracegirdle, Thomas J.},
  title = {Projected and historical amplification of moisture fluxes towards Antarctica by synoptic eddies},
  journal = {npj Climate and Atmospheric Science},
  year = {2026},
  doi = {10.1038/s41612-026-01376-x},
  url = {https://doi.org/10.1038/s41612-026-01376-x}
}