Tang et al. (2025) Reversed tropical-Arctic teleconnection under climate change

Identification

• Journal: npj Climate and Atmospheric Science
• Year: 2025
• Date: 2025-11-17
• Authors: Wenchao Tang, Bо Sun, Noel Keenlyside, Fei Li, Shengping He, Hua Li, Botao Zhou, Huijun Wang
• DOI: 10.1038/s41612-025-01243-1

Research Groups

• State Key Laboratory of Climate System Prediction and Risk Management/Key Laboratory of Meteorological Disaster, Ministry of Education/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, China
• Nansen Zhu International Research Centre, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
• Geophysical Institute, University of Bergen and Bjerknes Centre for Climate Research, Bergen, Norway
• Nansen Environmental and Remote Sensing Center, Bergen, Norway

Short Summary

This study reveals a reversal in the interannual relationship between winter El Niño-Southern Oscillation (ENSO) and subsequent spring Arctic surface air temperature (SAT) in recent decades, attributing this shift to changes in high-latitude atmospheric circulation and Rossby wave propagation patterns modulated by climate-change induced alterations in the westerly jet.

Objective

• To elucidate the interannual variations in the relationship between ENSO and Arctic spring SAT.
• To identify the underlying physical mechanisms modulating this tropical-Arctic teleconnection change, specifically how the evolution of the atmospheric background flow under climate change modulates this teleconnection.

Study Configuration

• Spatial Scale: Global, with a focus on the tropical Pacific (5°S–5°N, 170°W–120°W for Niño 3.4), North Atlantic (0°–60°N, 0°–80°W for AMO), and the Arctic region (north of 65°N).
• Temporal Scale: Centennial-long period (1940–2023) for analysis of interannual variability, with specific focus on two 21-year periods: 1958–1978 (P1, negative correlation) and 2001–2021 (P2, positive correlation). Seasonal analysis for winter (December–January–February) ENSO and subsequent spring (March–April–May) Arctic SAT.

Methodology and Data

• Models used: Coupled Model Intercomparison Project Phase 6 (CMIP6) historical simulations (20 models).
• Data sources:
  • Sea Surface Temperature (SST): HadISST (1° × 1°), ERSSTv5 (1° × 1°).
  • Surface Air Temperature (SAT): NASA GISTEMP (2.5° × 2.5°), HadCRUT5 (2.5° × 2.5°), ERA5 (2.5° × 2.5°).
  • Reanalysis (ERA5): Monthly mean geopotential height, temperature, wind, potential vorticity (PV), water vapor, and downward longwave radiation (DLR) (2.5° × 2.5°).
  • Indices: Niño 3.4 index, PNA index, AMO index.
  • Data Processing: 9-year high-pass Butterworth filter for interannual variability.
  • Statistical Tests: Monte Carlo test for sliding correlations, Student’s t-test for composite analysis significance.
  • Analysis Techniques: Composite analysis, wave activity flux analysis, calculation of vertically integrated northward heat and water vapor transport.

Main Results

• A robust reversal in the interannual relationship between winter ENSO (Niño 3.4 index) and subsequent spring Arctic SAT was identified: from a significant negative correlation during 1958–1978 (P1, correlation coefficient -0.50) to a significant positive correlation during 2001–2021 (P2, correlation coefficient 0.65).
• During P1 (negative impact period), positive winter ENSO anomalies led to negative Arctic SAT anomalies, primarily over the Barents-Kara Seas, associated with negative anomalies in atmospheric heat and water vapor transport from mid-latitudes to the Arctic.
• During P2 (positive impact period), positive winter ENSO anomalies led to positive Arctic SAT anomalies, particularly over the Kara Sea, Laptev Sea, Chukchi Sea, and Beaufort Sea, linked to positive anomalies in atmospheric heat and water vapor transport from mid-latitudes to the Arctic.
• The reversal is driven by changes in Rossby wave propagation patterns triggered by ENSO, which are modulated by decadal changes in the mean state of the upper-level westerly jet.
• These changes in the westerly jet (southward shift over the North Pacific, northward shift over North America/North Atlantic in P2 relative to P1) are primarily driven by regional differences in SST warming under climate change, specifically enhanced tropical upper-level warming (ETUW) in the Pacific and mid-latitude North Atlantic warming.
• CMIP6 multi-model ensemble simulations largely reproduce the observed reversal and underlying mechanisms.

Contributions

• Identifies and quantifies a robust reversal in the interannual tropical-Arctic teleconnection (ENSO-Arctic spring SAT relationship) under climate change.
• Elucidates the physical mechanisms behind this reversal, linking it to changes in high-latitude atmospheric circulation responses to ENSO, modulated by shifts in the westerly jet's position and intensity.
• Connects these westerly jet changes to regional disparities in SST warming (e.g., ETUW in the tropical Pacific, mid-latitude North Atlantic warming) under climate change.
• Advances understanding of Arctic spring climate interannual variability mechanisms, offering new insights for improving predictive capabilities.

Funding

• National Key Research and Development Program of China (grant No. 2022YFF0801704)
• National Natural Science Foundation of China (grant No. 42025502)
• Research Council of Norway (grant No. 328935)
• Nansen Center basics funding (grant No. 342624)
• MAPARC project (grant No. 328943)

Citation

@article{Tang2025Reversed,
  author = {Tang, Wenchao and Sun, Bо and Keenlyside, Noel and Li, Fei and He, Shengping and Li, Hua and Zhou, Botao and Wang, Huijun},
  title = {Reversed tropical-Arctic teleconnection under climate change},
  journal = {npj Climate and Atmospheric Science},
  year = {2025},
  doi = {10.1038/s41612-025-01243-1},
  url = {https://doi.org/10.1038/s41612-025-01243-1}
}