Whittaker et al. (2026) Distinct dynamical and thermodynamic pathways compound to amplify storylines of extreme atmospheric rivers in British Columbia

Identification

• Journal: npj Climate and Atmospheric Science
• Year: 2026
• Date: 2026-07-04
• Authors: Tim Whittaker, Alejandro Di Luca
• DOI: 10.1038/s41612-026-01476-8

Research Groups

• Centre d'Étude et de Simulation du Climat à l'Echelle Régionale (ESCER), Université du Québec à Montréal, Canada.

Short Summary

This study combines differentiable global climate modeling with high-resolution dynamical downscaling to construct physically plausible storylines of extreme atmospheric rivers in British Columbia. The results show that both dynamical and thermodynamic pathways contribute to the amplification of AR intensity, with the optimization primarily modifying the wind field and the pseudo-global warming signal increasing atmospheric moisture.

Objective

• Investigate the role of dynamical and thermodynamic drivers in amplifying the intensity of extreme atmospheric rivers (ARs) in British Columbia.
• Characterize the physical pathways through which such amplification can occur.

Study Configuration

• Spatial Scale: Regional scale, focusing on the western coast of North America, particularly British Columbia.
• Temporal Scale: Short-term to medium-term forecasts (up to 70 hours).

Methodology and Data

• Models used:
  • NeuralGCM (NGCM): A differentiable hybrid global climate model.
  • CRCM6-GEM5: High-resolution regional climate model for dynamical downscaling.
• Data sources:
  • ERA5 reanalysis data.
  • Historical AR events from the EDARA catalogue.

Main Results

• The optimization amplifies IVT across all five events, with peak ∆IVT values ranging from 300 kg m−1 s−1 to nearly 780 kg m−1 s−1.
• The precipitation response shows a net positive increase, ranging from 2 mm to 37 mm.
• The PGW experiment produces larger ∆IVT and precipitation responses compared to the optimization alone.
• The combined OPTPGW experiment yields IVT increases exceeding either experiment alone.

Contributions

• This study provides new insights into the physical pathways through which ARs amplify in intensity, highlighting the importance of both dynamical and thermodynamic drivers.
• The results have implications for understanding the potential impacts of climate change on extreme weather events in western North America.

Funding

• Not specified.

Citation

@article{Whittaker2026Distinct,
  author = {Whittaker, Tim and Luca, Alejandro Di},
  title = {Distinct dynamical and thermodynamic pathways compound to amplify storylines of extreme atmospheric rivers in British Columbia},
  journal = {npj Climate and Atmospheric Science},
  year = {2026},
  doi = {10.1038/s41612-026-01476-8},
  url = {https://doi.org/10.1038/s41612-026-01476-8}
}