Yang et al. (2026) Combined effects of arctic thermal conditions and ENSO on Eurasian winter temperature extremes

Identification

• Journal: Climate Dynamics
• Year: 2026
• Date: 2026-04-01
• Authors: Zibo Yang, Ruonan Zhang, Renhe Zhang, W. J. Hua
• DOI: 10.1007/s00382-026-08124-0

Research Groups

• Key Laboratory of Polar Atmosphere-ocean-ice System for Weather and Climate, Ministry of Education & Department of Atmospheric and Oceanic Sciences, Fudan University, Shanghai, China
• 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
• Shanghai Frontiers Science Center of Atmosphere‐Ocean Interaction, Fudan University, Shanghai, China

Short Summary

This study investigates the nonlinear combined effects of Arctic (Barents-Kara Seas) thermal conditions and ENSO on Eurasian winter mean and extreme temperatures, identifying tropospheric wave trains as the primary underlying mechanism. The findings highlight that specific Arctic-ENSO combinations lead to distinct Eurasian temperature responses, with significant implications for predicting cold extremes.

Objective

• To investigate the combined effects of Arctic (Barents-Kara Seas, BKS) thermal conditions and ENSO events on Eurasian winter mean and extreme temperatures, and their underlying mechanisms.

Study Configuration

• Spatial Scale: Eurasian mid-latitudes (30°–50°N, 80°–120°E) and high-latitudes (50°–65°N, 80°–120°E), Barents-Kara Seas (BKS) region (65°–85°N, 30°–90°E), Niño3.4 region (5°N–5°S, 170°–120°W), North Pacific, North America, Canadian Archipelago, North Atlantic, Siberia, Western North Pacific, Arctic.
• Temporal Scale: Winter (December–February; DJF) from 1960 to 2020 for reanalysis data, and 1960–2014 for CMIP6 model outputs. ENSO and BKS thermal indices defined for November through to the following February (NDJF).

Methodology and Data

• Models used: Coupled Model Intercomparison Project Phase 6 (CMIP6) (29 models, first ensemble member r1i1p1f1), Whole Atmosphere Community Climate Model (WACCM) for sensitivity experiments.
• Data sources: ECMWF Reanalysis 5th Generation (ERA5) reanalysis data (daily and monthly surface air temperature (SAT), sea level pressure (SLP), geopotential heights, and winds), Hadley Center Sea Surface Temperature (HadISST) data (monthly sea surface temperature (SST)).

Main Results

• A cold Barents-Kara Seas (BKS) troposphere is more prevalent during neutral ENSO winters, favoring a warm Eurasian winter.
• A warm BKS is typically observed during La Niña winters, leading to pronounced and extensive cooling in Eurasian mid-latitudes.
• During El Niño winters, cold and warm BKS events occur with equal probability. El Niño increases the frequency of extreme cold events in Eurasia due to the westward extension of the strengthened Aleutian low-pressure system, even with minor changes in winter-mean temperature.
• The combined effects of Arctic and ENSO on mid-high-latitude Eurasian temperatures are nonlinearly superimposed.
• The most robust mid-latitude East Asian cooling occurred with a combination of La Niña and BKS warming, resulting in a cold area of 29 million square kilometers and an area-averaged SAT anomaly of −0.44 °C.
• The physical mechanism behind the combined effects is primarily driven by tropospheric wave trains (e.g., Pacific-North America (PNA) teleconnection, North Atlantic Oscillation (NAO)), with stratospheric pathways playing a minor role.
• CMIP6 models generally reproduce the dominant features of Eurasian SAT anomalies and extreme cold event frequencies, though with some discrepancies in magnitude and specific regional effects compared to observations.

Contributions

• Highlights the critical and nonlinear role of differing Arctic (BKS) and ENSO combinations in determining Eurasian mid-latitude winter temperature and extreme cold events.
• Provides new theoretical support for improving the prediction of winter extreme weather events by considering joint Arctic-ENSO configurations.
• Offers a comprehensive investigation into the effects of eight distinct combinations of Arctic thermal conditions and ENSO events, an aspect previously less explored.
• Quantifies the non-linear superposition of Arctic and ENSO effects on Eurasian winter temperatures and associated atmospheric circulation anomalies.

Funding

• National Key R&D Program of China (Grant 2025YFF0812000)
• National Natural Science Foundation of China (NSFC, Grants 42288101, 42475024, 42075016)
• Joint Open Project of KLME & CIC-FEMD, NUIST (KLME202401)

Citation

@article{Yang2026Combined,
  author = {Yang, Zibo and Zhang, Ruonan and Zhang, Renhe and Hua, W. J.},
  title = {Combined effects of arctic thermal conditions and ENSO on Eurasian winter temperature extremes},
  journal = {Climate Dynamics},
  year = {2026},
  doi = {10.1007/s00382-026-08124-0},
  url = {https://doi.org/10.1007/s00382-026-08124-0}
}