Bokuchava et al. (2025) Contribution of Leading Natural Climate Variability Modes to Winter SAT Changes in the Arctic in the Early 20th Century

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Identification

• Journal: Atmosphere
• Year: 2025
• Date: 2025-12-09
• Authors: Daria Bokuchava, В. А. Семенов, T. A. Aldonina, Mirseid Akperov, Ekaterina Y. Shtol
• DOI: 10.3390/atmos16121391

Research Groups

Information not available from the provided text.

Short Summary

This study assessed the contributions of Northern Hemisphere natural variability modes to 20th-century Arctic winter temperature changes, revealing that these modes explain a significant portion of the variance, with forced-signal removal proving more effective than detrending for isolating internal dynamics.

Objective

• To assess the contributions of the Northern Hemisphere’s leading natural variability modes to winter temperature changes in the Arctic during the 20th century.

Study Configuration

• Spatial Scale: Arctic region, specifically across four equal-area Arctic sectors (European, Asian, Pacific, and North Atlantic), and the Northern Hemisphere for variability modes.
• Temporal Scale: 20th century, focusing on winter temperature changes.

Methodology and Data

• Models used: CMIP6 multi-model ensemble mean (used for subtracting externally forced signals).
• Data sources: HadCRUT5 (observed surface air temperature), CMIP6 (model simulations for residuals).
• Methods:
  • Comparison of two methodologies for removing externally forced signals from Arctic surface air temperature observations: linear detrending and subtracting the multi-model ensemble mean.
  • Statistical analysis to determine the percentage of total variance explained by northern extratropical modes.
  • Regional evaluation across four equal-area Arctic sectors.

Main Results

• Northern extratropical modes explain 66% (median) of the total variance in HadCRUT5 detrended observations, with the Atlantic Multidecadal Oscillation (AMO) index being dominant.
• These modes explain 30% of the total variance in observations-CMIP6 residuals, with the Pacific Decadal Oscillation (PDO) index being prominent.
• The forced-signal removal procedure (subtracting the multi-model ensemble mean) outperforms the linear detrending procedure in isolating unforced internal dynamics.
• A heterogeneous spatial pattern of Arctic surface air temperature modulation by climate indices was uncovered across the four Arctic sectors.
• The AMO's susceptibility to external forcings like greenhouse gases and aerosols was underscored.

Contributions

• Introduces a novel perspective on regional evaluation across four equal-area Arctic sectors, revealing heterogeneous spatial patterns of modulation by climate indices.
• Provides a comparative assessment of two methodologies (linear detrending vs. subtracting multi-model ensemble mean) for isolating internal variability from externally forced signals.
• Demonstrates that forced-signal removal using multi-model ensemble means is more effective than linear detrending for isolating unforced internal dynamics.
• Highlights the susceptibility of the AMO to external forcings, contributing to the debate on the causes of early 20th-century Arctic warming.

Funding

Information not available from the provided text.

Citation

@article{Bokuchava2025Contribution,
  author = {Bokuchava, Daria and Семенов, В. А. and Aldonina, T. A. and Akperov, Mirseid and Shtol, Ekaterina Y.},
  title = {Contribution of Leading Natural Climate Variability Modes to Winter SAT Changes in the Arctic in the Early 20th Century},
  journal = {Atmosphere},
  year = {2025},
  doi = {10.3390/atmos16121391},
  url = {https://doi.org/10.3390/atmos16121391}
}