Coll-Hidalgo et al. (2026) Future extratropical cyclones with more moisture and fewer associated atmospheric rivers

Identification

• Journal: npj Climate and Atmospheric Science
• Year: 2026
• Date: 2026-01-09
• Authors: Patricia Coll-Hidalgo, Luis Gimeno-Sotelo, José C. Fernández-Alvarez, Raquel Nieto, Luis Gimeno
• DOI: 10.1038/s41612-025-01307-2

Research Groups

• Environmental Physics Laboratory (EPhysLab), Centro de Investigación Mariña, Universidade de Vigo, Ourense, Spain
• Departamento de Estatística e Investigação Operacional, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
• CEAUL - Centro de Estatística e Aplicações, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
• Galicia Supercomputing Center (CESGA), Santiago de Compostela, Spain

Short Summary

This study projects that intense North Atlantic extratropical cyclones will transport significantly more moisture by the end of the century, with a geographic shift in moisture sources, but their association with atmospheric rivers is expected to weaken despite increased moisture availability.

Objective

• To characterize the response of moisture sources contributing to precipitation in intense North Atlantic extratropical cyclones (ETCs) to climate change using downscaled climate simulations and a Lagrangian approach.
• To re-evaluate the coupling between ETCs and atmospheric rivers (ARs) in the context of a warming climate using a refined approach based on shared moisture sources.

Study Configuration

• Spatial Scale: North Atlantic Basin (115.39°W–42.02°E, 19.41°S–59.51°N), with subregional analysis for the Eastern, Western, and Northern North Atlantic.
• Temporal Scale: Historical baseline (1985–2014) and end-of-century projection (2071–2100) under the high-emissions SSP5-8.5 scenario, focusing on the extended winter season (November–April).

Methodology and Data

• Models used:
  • Community Earth System Model version 2 (CESM2)
  • Weather Research and Forecasting system (WRF v3.8.1) for dynamic downscaling
  • FLEXPART-WRF model (version 3.3.2) for Lagrangian dispersion analysis
  • CyTRACK software for extratropical cyclone detection and tracking
  • TROVA software version 1.1.1 for Lagrangian moisture budget analysis
  • Image-Processing-based Atmospheric River Tracking (IPART) method for AR detection
• Data sources:
  • Dynamically downscaled simulations from CESM2 (CMIP6, SSP5-8.5 scenario).
  • ERA5 reanalysis (for historical period validation).

Main Results

• Moisture uptake (MU) associated with intense North Atlantic ETCs is projected to increase by approximately 14.5%, or 3.29% per Kelvin of global warming, by the end of the century.
• Subregional analysis reveals substantial MU increases during the deepest cyclone stages: 52.1% (11.8% K⁻¹) in the Eastern North Atlantic, 33.4% (7.6% K⁻¹) in the Western North Atlantic, and 29.1% (6.6% K⁻¹) in the Northern North Atlantic.
• The origin of moisture exhibits a geographic shift rather than a consistent increase within existing climatological source regions, likely linked to changes in storm-track pathways and ocean circulation.
• The strength of the ETC-AR association is projected to weaken, with weakly associated ETCs increasing by 2.26% and strongly associated ones decreasing by 2.05%.
• Future ETCs tend to couple with ARs closer to the moment of maximum deepening.
• Fully AR-associated ETCs show a statistically significant increase in median central mean sea-level pressure (4.23 hPa), suggesting a tendency towards weaker coupled cyclones.
• ETC-linked ARs exhibit significantly increased maximum integrated water vapour transport (IVT) across all quantiles in future projections.
• Intergroup differences between low- and fully associated ETCs (e.g., in central MSLP, IVT, and proximity to the AR axis) diminish and lose significance in a warming climate.
• Fully associated cases show pronounced poleward and eastward shifts, accompanied by increased moisture uptake, but the spatial separation between ETC centers and the AR IVT maximum increases.

Contributions

• Provides a novel characterization of future changes in moisture sources for intense North Atlantic extratropical cyclones using high-resolution downscaled climate simulations and a Lagrangian approach.
• Introduces a new moisture-source-based framework to quantify and analyze the evolving coupling between ETCs and atmospheric rivers under climate change.
• Offers new evidence that anthropogenic warming reduces the frequency of coupling between intense ETC moisture sources and ARs, indicating a potential transition in AR-mediated moisture transport.
• Highlights a divergent response where ARs show increased IVT, but ETCs become weaker, and the fraction of water vapor originating from coherent AR streams decreases, leading to a reduced distinctiveness in ETC-AR association.

Funding

• Xunta de Galicia (Galician Regional Government), grant no. ED481A-2022/128
• FCT – Fundação para a Ciência e a Tecnologia, project UID/00006/2023
• Xunta de Galicia, postdoctoral contract grant IN606B2024/016
• Ministerio de Ciencia, Innovación y Universidades, Spain (MICIU/AEI/10.13039/501100011033), SETESTRELO project (grant no. PID2021-122314OB-I00)
• Xunta de Galicia, Project ED431C2021/44 (Programa de Consolidación e Estructuración de Unidades de Investigación Competitivas (Grupos de Referencia Competitiva) and Consellería de Cultura, Educación e Universidade), co-funded by the European Union ‘ERDF A way of making Europe’ “NextGenerationEU”/PRTR
• Computing resources and technical support provided by CESGA and RES (Red Española de Supercomputación)

Citation

@article{CollHidalgo2026Future,
  author = {Coll-Hidalgo, Patricia and Gimeno-Sotelo, Luis and Fernández-Alvarez, José C. and Nieto, Raquel and Gimeno, Luis},
  title = {Future extratropical cyclones with more moisture and fewer associated atmospheric rivers},
  journal = {npj Climate and Atmospheric Science},
  year = {2026},
  doi = {10.1038/s41612-025-01307-2},
  url = {https://doi.org/10.1038/s41612-025-01307-2}
}